Posters | casca2013.phas.ubc.ca

CASCA 2013 Schedule for Posters

2013-05-28T17:30

Posters

Location: Sub Party Room

Chair: Betty Boop

Sliwa, Kazimierz *

Luminous Infrared Galaxies with the Submillimeter Array

We use high resolution CO observations to constrain the physical conditions (density, column density and temperature) of 14 ultra/luminous infrared galaxies (U/LIRGs) using a radiative transfer code. The 12CO J=3-2, 12CO J=2-1 and 13CO J=2-1 lines were observed with the Submillimeter Array and the short spacings of the 12CO J=2-1 and J=3-2 observations have been recovered using James Clerk Maxwell Telescope single dish observations. Currently, we have applied this method on two nearby LIRGs, Arp 299 and VV 114. The beam-averaged physical conditions of the two galaxy nuclei of Arp 299, IC 694 and NGC 3690, are consistent with a wide range of gas components, from warm moderately dense gas (T_kin > 30 and n(H_2)~ 0.3 - 3 × 10^3 cm^−3) to cold dense gas (T_kin = 10-30 K and n(H_2) > 3 × 10^3 cm−3). The overlap region of Arp 299 is shown to have a better constrained beam-averaged physical conditions with T_kin = 10-50 K and n(H_2) ~ 1-30 × 10^3 cm^−3 and these physical conditions are very similar to giant molecular clouds in M33. For VV 114, we have included CO J=6-5 observations to the model and found the physical conditions of VV 114 to be a hot (T_kin = 200-1000 K), diffuse (n(H_2)~ 2 - 8 × 10^2 cm^−3) molecular gas component. The heating source of this molecular gas component is not known but the AGN within VV 114 is the likely candidate.

Matzner, Christopher

Observational Signatures for Feedback Regimes in HII Regions

Ionized regions around clusters of massive stars are sites for mechanical feedback from star formation, and photo-ionization, stellar winds, photon momentum, and supernovae all contribute. The relative importance of these factors depends sensitively on the region geometry, for which different models adopt opposite limits. I describe observational constraints based on line ratios from the ionized zone, which record the radiation-gas pressure ratio and put strong constraints on the dynamical regime. These tracers are complementary to constraints from detailed x-ray observations, but can be applied both to individual regions and to entire galaxies. Bright H II regions, local starburst galaxies, and actively star-forming galaxies at high redshift all show evidence that stellar wind pressure is relatively minor, and that photon momentum is relatively important during the ionizing lifetimes of the massive stars.

Crabtree, Dennis

A Bibliometric Study of Canadian Astronomy Faculty

A database of all Canadian faculty and permanent researchers has been created. This database contains basic information such a affiliation, gender, year of PhD, institute of PhD and country of PhD. For each individual in the database information such as a list of papers, list of first author papers and citations to these papers have been downloaded from the ADS. This information is combined to analyse the publishing performance of Canadian researchers.

Newton, Jonathan *

Dust and Gas in NGC 3627 using new SCUBA-2 Images

The condensing of cold atomic hydrogen leads to a suitable environment for the formation of molecular hydrogen. In order for the molecular hydrogen to form, shielding is required and is often in the form of interstellar dust. Using high resolution submillimeter observations from the new SCUBA 2 instrumentation on the James Clerk Maxwell Telescope in conjunction with Herschel observations of NGC 3627, a model of the dust temperature has been made. The dust models can be combined with HI and CO observations to determine the molecular hydrogen column density for a given region. Future work includes determing the amount of molecular hydrogen present over the entire galaxy, and examining how the CO-to-H2 conversion factor changes per targeted region.

Mairs, Steven *

The Evolution of Pre-Stellar Cores: "Observing" Simulations to Compare with the JCMT and Predict with ALMA

Interpreting the nature of starless super-Jeans (SJ) cores (cores which exceed their Jeans mass stability limit) has been a prominent goal in the current literature. Assuming only thermal means of support, these over-dense cores should show signs of collapse under self-gravity; presumably forming proto-stellar substructure. Recently, Schnee et al. (2012, ApJ: 755:178, for example) found that as much as 20% of these SJ cores labelled as “starless” appear to contain deeply embedded protostars. In an effort to characterise the potential evolutionary stages of starless cores, with a specific focus on objects defined as super-Jeans, this project aims to "observationally" analyse time-dependent, numerical simulations of star-forming regions. These three dimensional adaptive mesh refinement (AMR), gravito-radiation-hydrodynamics simulations of turbulent molecular clouds have been generated by Dr. Stella Offner using the ORION code (Truelove et al. 1998, ApJ:495, 821). Column density maps from the simulations were first convolved to the JCMT beam in order to compare against the measurements of starless cores in nearby star-forming regions. The CLUMPFIND2D algorithm (Williams et al. 1994, ApJ 428, 693) was used to locate and determine the "observed" stability of the cores. The locations of these cores were then compared against the known positions of sinks within the simulations, where the sinks are expected to represent the formation of protostars. Atacama Large Millimetre/Submillimetre Array (ALMA) "observations" of simulations have also been performed in an attempt to probe the apparent substructure of identified, interesting objects.

Fedotov, Konstantin *

Star Cluster Formation in a Strong Shock

Stephan's Quintet (SQ) is a compact group of five interacting galaxies. It hosts a striking feature: a galaxy-scale shock (~ 40 kpc in length) in the intra-group medium (IGM). The shock was created by a high velocity (~ 1000 km/s) collision between the intruder galaxy NGC 7318B and a galaxy's worth of intra-group HI left-over from previous interactions in the group. Though SQ shows strong X-ray, radio synchrotron, and Halpha emission, detailed studies of molecular hydrogen imply that star formation is suppressed within the strong shock. We are undertaking a detailed study of the young star cluster population within the shock and other regions of SQ to evaluate this claim. The combination of HST archival (BVI+Ha imaging) and our new (U+Vm imaging) observations allow us to determine with improved precision key star cluster properties, such as ages, masses, and extinctions. Comparison of the young cluster population in SQ with those in other actively star-forming environments is key for determining the influence of the shock on star formation.

Griffin, Elizabeth *

Koch, Eric

Converging Flows in Star Forming Regions

Converging flows are a proposed method by which clusters gain significant mass from surrounding filamentary structure. Signatures of these flows are difficult to detect and previous research has been based primarily on by-eye analysis. We have developed a new method which algorithmically detects and characterizes converging flows in data sets. We simulated a set of turbulent clouds using ENZO and identified converging flows as regions of negative divergence in the velocity. In parallel, we created mock observational data from the simulation to mimic two dense gas traces, $^{13}$CO and HCO$^+$. We found that features with large gradients in the velocity centroid surface corresponded well to regions of negative divergence. To trace these regions of converging flows, we used a 2D Legendre Fit which has the benefit of being robust due to orthonormality between each order. Using our filament-detection algorithm, we were able to limit the search for converging flows to filamentary structure. In this way, we measured the converging flows in the simulation robustly using only a computational algorithm. This method allows large data sets to be analyzed quickly and efficiently for converging flows. This project was supported by an NSERC USRA.

Jackel, Benjamin *

Magnetic Helicity Transport in Accretion Disks

Pon, Andy *

Molecular Tracers of Turbulent Shocks in GMCs

Molecular clouds exhibit large linewidths, which are usually interpreted as being due to supersonic turbulence. This turbulence plays a key role in many theories of star formation, as it is believed to help support and fragment molecular clouds. Current numerical MHD simulations show that the turbulent energy of a molecular cloud dissipates on the order of a crossing time, but do not explicitly follow how this energy is released. We have run models of C-type shocks, based on Kaufman & Neufeld (1996), propagating into gas with densities near 1000 cm3 at velocities of a few km/s, appropriate for the ambient conditions inside of a molecular cloud, to determine which species and transitions dominate the cooling and radiative energy release associated with the dissipation of turbulent energy in shocks within molecular clouds. Combining these shock models and estimates for the rate of turbulent energy dissipation (Basu & Murali 2001), we produce synthetic CO spectra and predict those line emissions that will be observable with current and upcoming observational facilities such as Herschel, SOFIA, ALMA, and CCAT. We compare our synthetic shock spectra to the photodissociation region (PDR) models of Kaufman et al. (1999) and show that mid-J CO lines (e.g., CO J = 7 to 6) from molecular clouds illuminated by standard interstellar radiation fields are dominated by emission from shocked gas. We also present Herschel observations of these shock tracing lines. References: Basu, S. & Murali, C. 2001, ApJ, 551, 743 Kaufman, M. J. & Neufeld, D. A. 1996, ApJ, 456, 250 Kaufman, M. J., Wolfire, M. G., Hollenbach, D. J., & Luhman, M. L. 1999, ApJ, 527, 795

Martel, Hugo

The Connection between Star Formation and Metallicity Evolution in Barred Spiral Galaxies

We have performed a series of chemodynamical simulations of barred disc galaxies. Our goal is to determine the physical processes responsible for the increase in the central gas-phase metallicity and of the central star formation rate (SFR) observed in the SDSS. We define a 2kpc diameter central aperture to approximate the integrated spectroscopic fibre measurements from the SDSS. The chemical evolution observed within this central region depends critically upon the relative size of the bar and the aperture, which evolves strongly with time. At t~0.5Gyr, a strong bar forms via a disk instability, whose length is considerably longer than the 2kpc aperture. The stars and gas lose angular momentum and follow elongated orbits that cause an intense mixing of the gas between the central region and its surroundings. During the next 1.5Gyr, the orbits of the stars inside the bar do not evolve much, but the orbits of the gas contract significantly until the entire gas bar is contained in the 2kpc aperture, resulting in a net flux of gas into the central region. During this period, the metallicity in the central region increases steadily, and this enrichment is dominated by metal-rich gas that is flowing into the central region. The main result of this work is therefore that the observed enrichment in the centers of barred galaxies is not dominated by in-situ enrichment by stars formed in the center. Rather, star formation occurs along the full length of the bar, much of which occurs initially outside the 2kpc aperture. About 50% of the metals that end up in the central region originate from this extended bar-long star formation, but flow into the central region due to loss of angular momentum. We conclude that there is no direct connection between central SFR and central metallicity. The central metallicity does not originate exclusively from central stars. Instead, the global SFR (especially along the bar) and the large-scale flow of enriched gas play a major role.

Rosvick, Joanne

Star Formation near Berkeley 59 - Preliminary Results

We present preliminary results of a study of two star-forming regions near the young open cluster Berkeley 59, located in the Cepheus OB4 complex. A small association of suspected protostars in a dark cloud northwest of the cluster and two objects embedded in a pillar south of the cluster were investigated to determine their evolutionary stages. Data from 2MASS revealed that several of the objects are candidate YSOs on the basis of their excess near-infrared emission. Spectral energy distributions using 2MASS and WISE data (and JCMT continuum (SCUBA-2) data for the association region) indicate that five of the objects are protostars of evolutionary classes in the range I-II. JCMT heterodyne (HARP) observations revealed a weak CO outflow in the association region, and no outflow (but a suspected velocity gradient) in the pillar.

Hemachandra, Dimuthu *

Mysterious PAHs in M31

The detection of Polycyclic Aromatic Hydrocarbon (PAH) emissions in the interstellar medium was a major breakthrough in observational astronomy. Since then it has been found that PAHs are very common and very abundant in space. Recent findings have reported some unusual behavior of the PAH features in M31. Indeed, ISOCAM spectro-imaging observations of M31 showed that the nucleus and the bulge of this galaxy had very odd PAH spectra:- ,they are bright at 11.3 and 12.7 microns but lacking the usual 6.2, 7.7, and 8.6 micron bands. To investigate this further, we obtained new mid-infrared spectral maps covering the wavelength range 5 to 20 microns towards 12 regions in M31. These regions include the nucleus, two regions previously observed by ISOCAM, and 9 other regions chosen to cover a range of properties. We are presenting the preliminary results of the mid-IR spectra of these regions.

Cote, Stephanie

Canadian Gemini Updates

We will provide updates on Gemini operations over the last year, and provide some statistics of semesters 2013A and 2013B. The status of Gemini upcoming instruments and upgrades will be reviewed. You can stop by the poster to meet CGO staff who will be available to answer your questions about Phase I, Phase II, data reductions, etc.

Lamb, Masen

Non-Common Path Aberration Corrections for the MOAO system RAVEN

One of the major issues with the increasing complexity of contemporary AO systems is the non-common path aberrations (NCPA) introduced by the optical elements in the system that are not seen by the wavefront sensor. An example of such an AO system is RAVEN, the MOAO pathfinder, which uses two completely separate optical trains for wavefront sensing and wavefront correction. The NCPA introduced from the differential path in these arms must be sensed and compensated to help the AO system achieve the best correction possible. Since these aberrations are static the pre-compensation to the system is relatively straightforward. The standard approach to alleviate the NCPA in a system is to apply Phase Diversity (PD), which uses two images to estimate the system's phase: one image in focus and one with a known amount of defocus applied. There are other possible ways to estimate the NCPA of an optical system such as Focal Plane Sharpening, where an optimization algorithm finds a modal representation of the NCPA which, when applied, maximizes the Strehl ratio of the science image. We apply both techniques to estimate the NCPA on a simple test bench. The best technique (or combination of both) will be used with the same algorithms to calibrate the RAVEN NCPA.

Thanjavur, Karun

ALTAIR: Calibrated Balloon-Borne Light Sources for Precision Photometry

Observational systematic uncertainties, a large fraction of which arise from the current practice of using standard stars alone for absolute photometric and flux calibrations, are the dominant limitations facing the ongoing ground based surveys to constrain the properties of dark energy and cosmological parameters. Conley et al (2011) and similar reviews of the observational systematics in dark energy experiments have repeatedly highlighted the necessity for photometric calibration precision to better than the current 1-2% barrier in order to fully utilize the statistical benefits of the rapidly expanding sample sizes from these massive surveys. In this context, we present ALTAIR, a stratospheric balloon borne, NIST- and NRC-INMS-calibrated set of small, optical, monochromatic light sources as the preferred standard source to fully characterize the telescope and detector, while measuring the atmospheric transmission simultaneously with the science observations. We justify the claim of sub-percent photometric accuracy using simulated calibrations of the Pan-STARRS environment, as well as field measurements of a 532nm laser source borne at 20km by a weather balloon. We discuss upcoming flight tests at Mt. Hopkins and Pan-STARRS in Fall 2013, future plans for microwave calibrations of South Pole CMB observatory, and also a nanosat designed by UTIAS-SFL to carry the calibration laser source in near earth orbit.

Hutchings, John

UVIT and the Astrosat observatory

The poster will describe the current status and performance of instruments on the Astrosat observatory, with particular attention to the UV imaging telescopes. Canada has a guaranteed share of observing time on this multi-wavelength facility, which is to be launched in 2014.

Lavoie, Sebastien *

Absorption lines study and spectra simulator : New elements to help in future project planning with SITELLE

A wide-field Imaging Fourier transform spectrometer (FTS) like SITELLE can collect millions of spatially resolved spectra of extended objects, such as Galactic nebulae and nearby galaxies. Although most commercial and remote-sensing FTS are used to characterize absorption line spectra, this type of instrument is notoriously more efficient at analyzing emission line sources. SITELLE's prototype, SpIOMM (attached to the 1.6-m telescope of the Observatoire du Mont-Megantic), has recently been used to observe open clusters and the elliptical galaxy M87 to demonstrate the feasibility of absorption lines study with SITELLE; we present these data in this poster. In addition, we present the spectra simulator software that will be available to help astronomers estimate the feasibility of their observations and the time needed to obtain the resolution and SNR they need.

Safi-Harb, Samar

The Astro-H X-ray Mission

Astro-H is an international X-ray satellite, led by JAXA, with participation from NASA, ESA and other institutions from Europe and the USA. Recently the Canadian Space Agency became a partner and will provide the Canadian Astro-H Metrology System (CAMS). Astro-H, planned to be launched in 2015, will investigate the high-energy Universe via four instruments that will operate simultaneously, achieving an unprecedented spectral resolution and sensitivity in the 0.3-12 keV band together with a broadband coverage in the 0.5-600 keV. Astro-H's unique capabilities will open a new window to understanding the extreme conditions and phenomena in the Universe, including gas velocities and metallicities of the hot atmospheres of clusters, the chemical content and velocity distribution of supernova ejecta, the search for thermal plasma in synchrotron-dominated supernova remnants and pulsar wind nebulae, the physics of AGN outflows and the measurement of black holes spin. We here highlight the mission specifics, science objectives and potential, and Canadian participation to the science and the development of CAMS. Co-authors: Luigi Gallo (St Mary's U.), Brian McNamara (U. Waterloo), Casey Lambert (St Mary's U.), Helen Russell (U. Waterloo), Astro-H Team

Monin, Dmitry *

Robotic Operation of the DAO 1.8-m Plaskett Telescope

The DAO 1.2-m telescope has now been successfully used to obtain astronomical spectra in unattended robotic mode for a decade and approximately 70% of the nights scheduled on the telescope are now used in this fashion. The availability of such robotic operation has boosted the telescope's subscription rate by approximately 50% since telescope users no longer have to travel to Victoria in order to conduct their observing programs (particularly in the winter months when long stretches of bad weather can make such travel unproductive). The other DAO observing facility, the venerable 1.8-m Plaskett telescope, is currently only available for classical observing by visiting or staff astronomers. In order to make the Plaskett telescope more attractive for use by a broader Canadian (and perhaps international) astronomical community, we have begun upgrades to the 1.8-m dome and telescope as part of an effort to enable robotic operation of this facility for both imaging and spectroscopy. This work is benefiting from the extensive experience we have obtained from our automation of the 1.2-m telescope. In this paper we present an overview of the proposed system as well as our implementation plan. We hope that the 1.8-m telescope will be available for some limited shared-risk robotic observing as early as the 3rd quarter of 2013.

Robertson, Damien

A survey of clump/core properties of the Perseus molecular cloud using Herschel submm observations.

The earliest stages of stellar evolution witness protostars forming from clumps and cores that condense from molecular cloud complexes. The conditions in which these clumps and cores form impact the final distribution of stellar characteristics among these new stars. Observing the pre-stellar clumps/cores and environment helps bridge a gap in stellar evolution between diffuse molecular medium and the resulting main sequence star. Using Herschel PACS/SPIRE instruments, continuum maps of the Perseus molecular cloud have been constructed across 5 wavebands, 70 – 500 microns. The total area of the observed maps is approximately 13 square degrees. The clump finding program GETSOURCES was performed and a census of pre-stellar clumps/cores was compiled. We summarize the results of this census and attempt to construct a clump/core mass function using individual source temperatures obtained through SED fitting.

Lianou, Sophia

Probing the interstellar medium of the NGC1569 super-star cluster population with Herschel

NGC1569 is one of the strongest nearby starburst dwarf galaxies as revealed by its super-star cluster population. Its current distance estimate places NGC1569 in the IC342 group of galaxies. Thus, tidal interactions with the IC342 group member galaxies may have triggered the starburst and the super-star cluster formation. We focus on the interstellar medium properties surrounding the super-star cluster population of NGC1569. We use Herschel observations, as well as ancillary multiwavelength observations, in order to derive the physical properties of the interstellar medium. Our ultimate goal is to study the impact of the massive star formation on the interstellar medium properties.

Schirm, Maximilien *

Submillimeter Observations of Excited CO and [CI] in the Antennae (NGC 4038/39): Warm and Cold Molecular Gas

Using the Herschel-SPIRE Fourier Transform Spectrometer (FTS), we have acquired 2 fully-sampled maps of the Antennae (NGC 4038/39), a nearby (22 Mpc) ongoing merger between two gas rich spiral galaxies. These observations were performed as part of the Very Nearby Galaxies Survey. We have detected emission from 5 CO transitions (J = 4−3 to J = 8−7) and both [CI] transitions, all of which are tracers of cold and warm molecular gas. Using a radiative transfer analysis, we find that there are at least two components to the molecular gas in the Antennae: one which is cold (T ∼ 20 K) and dense (n(H2) > 1000 cm^−3), and another which is both warmer (T ~ a few hundred K) and denser (n(H2) > 10000 cm^-3). In addition, a local thermal equilibrium analysis of the detected [CI] transitions confirms the existence of a cold component with temperature T ~ 20 K. We investigate the source of molecular gas heating in the Antennae and find that in the overlap region and the nucleus of NGC 4039, the CO line ratios of the warm component can be modelled by a photodissociation region (PDR) with a UV field strength greater than 10 times that of the Habing field. It is likely that throughout the galaxy, PDRs and supernovae due to the increased star formation rate contribute significantly to the overall heating of the molecular gas. We conclude that both the fraction and temperature of warm molecular gas in the Antennae is smaller than in more compact star forming galaxies such as M82 and Arp 220.

Jones, Scott *

Polarisation Observations of H2O 5_{32}-4_{41} 620.701 GHz Maser Emission with Herschel-HIFI in Orion KL

With extremely high intensities and spatially focused radiation, masers are an exceptional tool to investigate star formation as it occurs within molecular clouds. We have collected data from the heterodyne spectrometer HIFI on board the Herschel spacecraft, over multiple observing periods, in order to measure the linear polarization of the recently verified 5_{32}-4_{41} water maser transition in the Kleinmann-Low nebula in the Orion Molecular Cloud (OMC). Simultaneous polarization data of the same source from the Effelsberg radio telescope, of the more widely studied 22.235 GHz transition over the same ten-month period, has led to drastically different results. I will review the polarization results from both instruments and make attempts to reconcile the noted large difference in polarization magnitude. The time-span of our observations have also provided us an opportunity to draw some preliminary conclusions on the evolution of the source itself.

Wilson, Christine

New SCUBA-2 maps from the JCMT Nearby Galaxies Legacy Survey

The JCMT Nearby Galaxies Legacy Survey is an HI-flux-selected sample of 155 galaxies within 25 Mpc. We present a gallery of spectacular new SCUBA-2 images at 450 and 850 microns for several of the galaxies observed in the past year. We compare the results to Herschel maps at 250 and 500 microns to highlight the impact of the higher angular resolution of the SCUBA-2 data. We also discuss plans for completion of the survey over the next 16 months.

Makiwa, Gibion *

The structure of the Class I protostar Elias 29 as revealed by the Herschel-SPIRE Imaging Spectrometer

Elias 29 is a Class I protostar found in the nearby (d~160 pc) rho-Ophiuchus molecular cloud. We present Herschel-SPIRE imaging Fourier Transform Spectrometer observations of Elias 29 from 447 to 1544 GHz at a spectral resolution of 1.2 GHz which corresponds to R = 400 to 1300. Within this frequency range we detect emission lines of the CO ladder from J=4-3 to J=13-12. Using fully sampled jiggle maps of these transitions over a 2'x2' field of view we confirm the presence of several different components along the line of sight that contribute to the emission. We constrain the gas temperatures in the identified components. Our data extend the continuum SED of Elias 29 observed with ISO. We compare the resultant SED with a grid of protostellar models.

Beaulieu, Sylvie F

Herschel: Post-operation

On the 29th of April 2013, the Herschel Space Observatory, launched on 14 May 2009, has exhausted its supply of liquid helium coolant, ending a very successful mission to observe the cool Universe. As we are now entering the post operation phase of Herschel, more science data in the Herschel Science Archive gets released into public domain every day. This represents an excellent opportunity for additional astronomical discoveries for the larger Canadian astronomical community. The University of Waterloo Herschel-HIFI Group remains dedicated to help you achieve your scientific goals.

Karr, Jennifer

A Monte-Carlo Program for Simulating and Analyzing Scattered Light Images of Disks

Coronagraphic scattered light images in the near infrared can be a powerful probe of the surface of circumstellar disks. However, comparing image data to models is a time consuming task, particularly for large projects with multiple sources. We present a software tool that lets users quickly calculate a grid of models scattered light images in multiple polarizations, varying the disk geometry, inclination and dust model, and efficiently compare the results with observations.

Fraser, Wesley

Occultations by Kuiper Belt Objects

Observation of stellar occultations by a planetesimal is an extremely powerful technique to characterize many properties of the occulting object, including its size, shape, and atmospheric extent. This technique is extremely useful for Kuiper Belt Objects, the proximities of which make it virtually impossible to determine shape and atmospheric properties with any other remote sensing technique currently available. Recently our group has devised a new means of predicting when these rare occultations will occur. The technique utilizes a small (~1 hr) set of observations with the MegaCam, from which a Master Point Source Catalog (MPSC) is produced with a typical astrometric accuracy of less than ~0.02”. As well, these observations are used to correct the ephemerides of the target KBOs. The result is occultation predictions with precision of 2000 km or better - similar to the size of the target KBOs - as far into the future as 2016. I will present the results of a pilot study of 7 objects, and some preliminary efforts to catch the object, Quaoar, in the act of occultation. With observations made by the Acquisition Camera on Gemini-N of Quaoar’s close passage to a star, we have been able to place stringent upper limits on Quaoar’s atmosphere, with a surface pressure no more than 25 nanobars. These observations reveal that Quaoar has an unexpectedly cold surface temperature less than 41 K, and demonstrate the utility of occultation observations in characterizing remote planetesimals.

Pike, Rosemary *

Color in the Kuiper Belt: Size vs Class

Color measurement observations introduce non-intuitive biases in size-color relationships that cannot be disentangled without a well characterized sample population and a systematic color measurement followup. Peixinho (2012) report that the distribution of KBOs color varies as a function of object size regardless of object class. Tegler (2003) find that KBO color distributions are a property of dynamical classification. We construct a synthetic model of the observed Kuiper belt and assign colors based on these two color distribution scenarios. One model has B-R color distribution dependent on H magnitude (the H-Model) and another model has B-R color distribution based on object classification (the Class-Model). These synthetic B-R color distributions were then modified to account for observational flux biases, creating a 'color-biased' synthetic sample. For both the original synthetic color distributions and the color-biased versions, the B-R distributions of 'Hot' and 'Cold' KBOs were compared with two observed B-R distributions of 'Hot' and 'Cold' KBOs: a sample of CFEPS objects, and a sample drawn from the Meudon Multicolor Survey (2MS, Doressoundiram 2007). We also explored the effects of different classification methods, using perihelion and semimajor axis in addition to the standard inclination based dynamical classifications. We found that the different classification schemes had minimal effects on the results, but depending on the assumptions about the selection process, either model for color dependence (orbital classification or size) can be supported by the observational data, with a slight preference for classification.

Gregory, Philip

Additional Keplerian Signals in the HARPS data for Gliese 667C from a Bayesian Re-analysis

Phil Gregory, Samantha Lawler, Brett Gladman, UBC: A re-analysis of Gliese 667C HARPS radial velocity data was carried out with a Bayesian multi-planet Kepler periodogram (from 0 to 7 planets) based on a controlled fusion MCMC algorithm. The most probable number of signals detected is 6 with a Bayesian false alarm probability of 0.012. The 6 signals detected include two previously reported with periods of 7.2 and 28.1 days, plus additional periods of 30.8, 38.8 , 53.2, and 91.3 days suggesting the possibility of further planets. Stellar diagnostic information suggests that the 53 day signal is the second harmonic of the stellar rotation period and is likely the result of surface activity. N-body simulations are underway to determine which of the remaining signals are consistent with a stable planetary system. At present, we have not found a long term (10^7 yr) stable 5 planet system consistent with the data. If we assume the 30.8 d period is an additional spectral artifact, we are able to identify a long term stable system with periods of 7.2, 28.1, 38.8, and 91.3 d. The corresponding M sin i values are 5.4, 4.8, 2.4, and 5.4 ME and the semi-major axes inferred for the 28 and 38.8 d signals place them in the central region of the habitable zone. Further analysis is underway to define the probability bubble of stable orbits corresponding to this candidate 4 planet system.

Leahy, Denis

The nature of the complex x-ray and radio emission in gamma Cygni

The gamma Cygni region is complex and contains bright HII regions and at least one supernova remnant (G78.2+2.1). Previous studies have come up with conflicting views on the nature of G78.2+2.1. Here an analysis of new radio and X-ray observations is performed to determine the nature of the supernova remnant (SNR) and its surroundings. The atomic hydrogen (HI) line and radio continuum data from the Canadian Galactic Plane Survey is used to obtain a new HI absorption distance to the SNR and an HI column density. X-ray images of the gamma Cygni region are constructed using ROSAT survey data, ROSAT pointed observations and Chandra observations. A second foreground x-ray shell is found which overlaps the northern part of G78.2+2.1and which can be separated from G78.2+2.1 based on its X-ray spectrum. Two hard X-ray sources are found overlapping G78.2+2.1: one is a diffuse extragalactic source, probably a background galaxy, and one is a point source with the same distance as G78.2+2.1. The point source may be physically related to the SNR. X-ray spectra yield temperatures and emission measures from which the evolutionary state of G78.2+2.1 and the foreground shell are inferred.

Parrish, Ian

Galaxy Clusters from Inside to Out: Thermal Instability and Nonthermal Pressure Support

Clusters of galaxies are the largest gravitationally-bound objects in the universe, and as such are useful as probes of both cosmology and astrophysics. To understand these objects as well as related problems in galaxy formation and black hole growth, we must understand the hot, dilute intracluster medium (ICM) that dominates the baryonic mass. In the cores of cool-core galaxy clusters, I will explore the balance between heating and cooling processes and explain when and how thermal instability occurs. The resulting cool gas can form filaments or feed a central black hole. Our results are in generally good agreement with observations. I will describe a degree of thermal self-regulation of clusters and hot halos that can be achieved from this process and its consequences. Finally, I will move to the cluster outskirts and highlight the role of conduction-driven convection in the outskirts of galaxy clusters. The non-thermal pressure support from this vigorous convection has implications for our interpretation of ongoing SZ surveys and cosmology.

Alarie, Alexandre *

Hyperspectral view of Cas A and Cygnus Loop

We have obtained spatially resolved spectra for two different supernova remnants: Cassiopeia A and Cygnus Loop. We observed these two objects in the spectral range 475-515 nm and 648-682 nm, encompassing the Hβ, [O III] λ4959, λ5007, Hα, [N II] λ6548, λ6584, and [S II] λ6717, λ6731 emission lines, with the imaging Fourier transform spectrometer SpIOMM at the mont Mégantic Observatory in Québec. As a young remnant, Cas A filament’s velocity easily exceed 3000 km/s causing a significant Doppler shift in the spectra. Using both SpIOMM and Hubble observations, we derived the radial and transverse speed for multiple filaments and obtained a full three-dimensional spatial view of Cas A. As for Cygnus Loop, a much older remnant, we obtained over a million spectra with SpIOMM, allowing a detailed analysis of the interaction between the shock front and the interstellar medium around the nebula.

Glass, Florian

The binary fraction of small KBOs

Recent works have shown that a small fraction of Kuiper belt objects (KBOs) are in pairs. These binaries record signatures of the formation conditions in the Kuiper Belt. As binaries are highly sensitive to collisions, the existence of binaries today places a strong constraint on the formational environment and collisional evolution history of the Kuiper Belt. Observational limits have made it difficult to resolve binary pairs and to date only tens of pairs have been discovered. Here we present the preliminary results of a binary search using data taken for the Hubble/WFC3 Test of Surfaces in the Outer Solar System (H/WTSOSS; Fraser and Brown, 2012) to resolve and characterize binaries. H/WTSOSS utilized 4-band observations to measure basic compositional properties of 120 KBOs. While performing this survey, it was found that the theoretical WFC3 Point Spread Functions (PSFs) were a poor representation of the observed PSFs. This has prevented a straight forward search for partially resolved binary KBOs. We present our newly developed technique to improve the WFC3 PSF from the H/WTSOSS observations. The standard technique makes use of the Tiny Tim theoretical PSF. In order to improve the WFC3 PSF, we take the Tiny Tim model, and perturb its distortion parameters to match the PSFs of bright background stars in the images, all while accounting for the motion of the KBO and the background stars. Here we present the details of the technique and the preliminary results our KBO binary search.

Ritter, Christian

Complete yields for low, intermediate and massive stars for 0.02 > Z > 1.e-4

Authors: C. Ritter, F. Herwig, M. Pignatari, R. Hirschi, C. Fryer, A. Heger, S. Jones, P. A. Denissenkov & the NuGrid collaboration We have calculated stellar evolution tracks for AGB, super-AGB and massive stars for masses between 1 and 25Msun and metallicities between Z=1e-4 and 0.02, using the MESA stellar evolution code. For massive stars, all sequences are followed to collapse. All tracks involve standard mass loss assumptions, convective boundary mixing and detailed resolution of thermal pulse-induced nuclesosynthesis, mixing and feedback, for example from the hot dredge-up in massive, low-Z AGB and super-AGB stars. All stellar evolution tracks have been post-processed for nucleosynthesis yields of all elements, using the NuGrid codes.

Griffin, Elizabeth

epsilon Aurigae - the Sting in the Tail

Epsilon Aurigae is the 'famous' eclipsing system which goes into a 2-year eclipse every 27.1 years. However, the [composite] spectrum does not change during eclipse, but remains resolutely that of the F0 Ia-type primary star, nor is there a detectable secondary photometric eclipse. The eclipsing body is clearly some sort of extended opaque disk, but its provenance and evolution are as yet still matters for conjecture. The system underwent an eclipse from 2009-2011. It was monitored mercilessly by photometrists and spectroscopists, and those new data will result in a considerable degree of refinement of the properties and parameters of both components. But however high the quality of the new data, an understanding of the geometry and evolution of the system depends critically upon knowing whether certain features are repetitive or random, so it is of paramount importance to conduct comparisons between different eclipse data. Unfortunately, born-digital data and data archiving were scarcely happening even one eclipse ago. Our unique contribution has been to include the rich data sets from the 1956 and 1983 eclipses by digitizing about 100 high-dispersion photographic spectra. Those historic data are proving of immense worth, enabling us to derive a much clearer understanding of the properties, stability and rotation of the cool opaque component, as well as shedding some light on its mass. Even more intriguing has been the discovery of a very confined stream of material that emanates from the F star towards the cool component at a very tightly confined phase interval and location during the end of egress, and at no other time. The paper will describe the evidence and a possible model of what might be going on.

Rahmani, Sahar *

Effects of gas clouds and existing stars on current star formation in M31: Testing the Extended Schmidt Law

The empirical Schmidt-Kennicutt Law shows a power-law relationship between the volume densities of the star formation rate (SFR) and gas mass. It is still unclear whether or not this correlation is fundamental and universal. Shi et al. (2011) argued that volume densities of SFR are not only related to gas mass but also to stellar mass surface density. This relation is known as the Extended Schmidt Law. We present preliminary results of our tests of the Extended Schmidt Law for the Andromeda galaxy. We estimate the SFR using a combination of H-alpha and 24-micron data, the stellar mass with mid-infrared IRAC imaging, and the gas mass density with HI+CO maps.

Howard, Corey

Radiative feedback of forming star clusters on their GMC environments: Theory and simulation

Star clusters form from dense clumps within a molecular cloud. Radiation from these newly formed clusters feeds back on their natal molecular cloud through heating and ionization which ultimately stops gas accretion into the cluster. Recent studies suggest that radiative feedback effects from a single cluster may be sufficient to disrupt an entire cloud over a short timescale. Simulating cluster formation on a large scale, however, is computationally demanding due to the high number of stars involved. For this reason, we present a model for representing the radiative output of an entire cluster which involves randomly sampling an initial mass function (IMF) as the cluster accretes mass. We show that this model is able to reproduce the star formation histories of observed clusters. To examine the degree to which radiative feedback shapes the evolution of a molecular cloud, we use the FLASH adaptive-mesh refinement hydrodynamics code to simulate cluster formation in a turbulent cloud. Unlike previous studies, sink particles are used to represent a forming cluster rather than individual stars. Our cluster model is then coupled with a raytracing scheme to treat radiative transfer as the clusters grow in mass. This poster will outline the details of our model and present preliminary results from our 3D hydrodynamical simulations.

Pavlovskii, Konstantin

Response of red giants to dynamical-timescale atmospheric mass loss

The process of dynamical-timescale mass loss in red giants is one of regrettable uncertainties constraining our knowledge of the evolution of binary systems consisting of a red giant and a compact accretor where at the inception of a possible common envelope event giant overfills its Roche Lobe. Unfortunately, even with today's powerful computers a full-fledged hydrodynamical simulation of this spectacular astrophysical phenomenon is not possible. We study approaches to model mass loss from giant's atmosphere using existing one-dimensional stellar code "MESA star". Because the process of mass loss is both non-adiabatic and highly non-hydrostatic, such simulations are at the edge of capabilities of even modern and sophisticated stellar libraries. We propose a model for self-consistent atmospheric mass loss that takes into account the importance of dynamical-timescale pulsations induced by mass loss and shows the need for more advanced treatment of thermal effects arising in the donor's envelope.

Pellerin, Anne

NoMaDS: The Northern Massive Dim Stars Survey

We present the Northern Massive Dim Stars Survey (NoMaDS), a high-resolution spectroscopic campaign at the 9.2m Hobby-Eberly Telescope. The project aims at building the most complete and homogeneous spectroscopic database of hot, massive Galactic O stars. NoMaDS is part of an international collaboration that combines observations from Chilean, Spanish, and Texan facilities. The contribution of NoMaDS is to complement the other sister surveys by providing high signal-to-noise echelle spectra (R=30000) of Galactic OB stars that are too faint for smaller ground-based telescopes. NoMaDS will provide a sample of about 200 stars, many of which have never been observed before at such a high resolution. Here we present the details of the survey, as well as echelle spectra obtained with the High Resolution Spectrograph since May 2011. This survey will provide unprecedented spectroscopic database for a more accurate spectral classification, a quantitative analysis using atmosphere modeling, the detection and follow up of the orbits of massive spectroscopic binaries as well as the study of diffuse interstellar bands.

Lepo, Kelly *

How to find a Symbiotic Star

Symbiotic stars consist of a hot white dwarf and a giant companion. Their number is an important piece of evidence for solving the mystery of the nature of type Ia supernova progenitors --- not only are they possible single degenerate (white dwarf and a normal star) progenitors by themselves, all double degenerate (two white dwarf) progenitors should also evolve through a symbiotic phase. Previous systematic surveys looking for symbiotic systems have failed due to the large number of contaminants among candidate sources. I will present the preliminary results of an AAOmega/FLAMES spectroscopic survey of the Small Magellanic Cloud looking for symbiotic stars. I will discuss some of the challenges of separating symbiotics from contaminating sources and discuss the unique characteristics of symbiotics that may be used to find them in large surveys.

Berg, Trystyn *

A search for boron in high redshift galaxies

For the first time, a comprehensive study has been completed in an attempt to measure the abundance of boron outside the Local Group. Although the exact origin of boron is not well understood, its abundance can provide constraints on the cosmic ray flux and star formation history of a system. This survey consists of observing boron in the high redshift ISM of 30 damped Lyman alpha systems. I will present the results from this study, and discuss how the apparent excess of boron implies a higher cosmic ray flux and what that means for galaxies at high redshift.

Rahman, Mubdi

Measuring Redshift Distributions using Galaxy Clustering

The measurement of distances is a fundamental problem in astrophysics. The classical technique using spectroscopy to measure redshifts is expensive and limited to the brightest of objects with identifiable spectral features. However, the advent of large spectroscopic catalogs has enabled new techniques to determine distances based on galaxy clustering. I will present the galaxy clustering redshift recovery technique, show its applicability to real world data, and present some unexpected results applying the technique to existing catalogs of photometric redshifts, the GALEX point source catalog, and other large data sets.

Sanchez-Janssen, Ruben

The Impact of Dwarf-Dwarf Galaxy Tidal Interactions

We present an investigation of the impact of dwarf-dwarf galaxy tidal interactions on their morphological and star formation properties. The UGC5205 close pair consists of two low-mass (M* ~ 5E7 Msun), late-type galaxies with a relative projected distance of only 10 kpc, and no nearby massive companions. We make use of SDSS spectroscopy and deep optical imaging to show that these tidal interactions are efficient at i) triggering synchronized galaxy-scale starbursts; ii) forming young (t < 1 Gyr), massive star clusters; and iii) creating tidal tails and streams that modify their stellar structure and content. We conclude that dwarf-dwarf interactions can be an important 'pre-processing' mechanism that acts before the dwarfs are affected by a more massive galaxy, profoundly impacting their star formation histories and morphologies.

Janssens, Steven *

Red Nuggets in the Adaptive Optics Deep Field

The full potential of adaptive optics (AO) for extragalactic astronomy has yet to be realized. Despite laser guide stars, natural guide stars are still needed for the tip-tilt correction. However, all existing deep fields are located near the galactic poles, to minimize extinction and the number of bright stars. Unfortunately, this also minimizes the number of natural guide stars, crippling AO in these fields. With the Gemini Multi-Conjugate AO System (GeMS), the first multi-conjugate AO system on a large telescope, commissioned and requiring not only 1, but 3 natural guide stars in equilateral triangles, a new approach was needed. Our group found a unique location in the sky with both low extinction and high stellar density, yet few bright stars, making it ideal for observations with AO. We have named this field the Adaptive Optics Deep Field (AODF). For our own science, we have submitted a proposal to image high-z compact elliptical galaxies ('red nuggets') in the AODF with GeMS at restframe visible wavelengths at twice the resolution of HST. In addition, in the near future, we plan to release a generally useful public catalog of targets in the AODF for future observations with both current generation AO telescopes and upcoming 30 metre class telescopes, which will critically depend on AO.

English, Jayanne

The Future is Now: A Current Twist on Visualizing Halos of Spiral Galaxies.

Radio telescope data, whether from continuum emission or spectral line observations, are rich with structure in the halos of spiral galaxies. These features can trace tidal debris or material blown out of the disk. We present explorations in visualization techniques that attempt to detect and assess characteristics of these structures. Our investigations include (1) a preliminary use of computer interactives for multi-wavelength comparisons and (2) displaying 3-D velocity fields in a holographic mode that employs head-tracking devices.

Rogers, Adam

Applications of global optimization methods in high-energy astrophysics

Genetic algorithms (GAs) and particle swarm optimizers (PSOs) are optimization algorithms that are inspired by the principles of biological evolution. These global optimization methods are powerful parameter search and exploration tools due to their robust behaviour searching high-dimensional, multi-modal parameter spaces. GAs and PSOs are not generally prone to the difficulties that are associated with local methods such as gradient descent which are widely used in the literature. In my doctoral thesis work (2012), I made extensive use of the Ferret GA and Locust PSO to perform large non-linear searches through the parameter spaces of analytical gravitational lens density distributions. As an application to the field of neutron star astrophysics, we describe our on-going efforts to develop a multi-objective approach to simultaneously model the spectra and pulsations of highly magnetized pulsars, which can constrain the equation of state of these enigmatic objects. More generally, our ultimate aim is to design an X-ray spectral fitting package that makes use of the spectral models already written for XSPEC, the software package commonly used by the X-ray community worldwide, to model a wide range of astrophysical sources. The use of multi-objective global optimization methods offers a robust, novel and innovative approach to the exploration of the parameter spaces of spectral models. Co-authors: S. Safi-Harb, J. D. Fiege, T. Enoto

Thornburg, Jonathan

Extreme-mass-atio binary black hole inspirals as probes of strong-field gravity

Consider a stellar-mass black hole (mass ~ 10 solar masses) orbiting a supermassive black hole (mass ~ 10^6 solar masses). In the final few years before merger, such a system makes on the order of 10^5 orbits with orbital separation less than 10 times the supermassive black hole's radius. The resulting gravitational waves (GWs) are a sensitive probe of the orbital dynamics, and measuring the GW phase as a function of time allows a high-precision test of strong-field general relativity. To this end, I will discuss the problem of modelling /ab initio/ the radiation-reaction "self-force" acting on the small body and the resulting orbital evolution. I will describe the singular nature of the perturbation equations and the puncture-function regularization scheme, and I will present recent results showing the dependence of the self-force on the supermassive black hole's spin for a scalar-field test system.

Fonseca, Emmanuel *

Relativistic Spin Precession in PSR B1534+12

Pulsars in relativistic binary systems have provided the most stringent constraints on strong-field gravity to date. PSR B1534+12, a 37.9-ms pulsar in a relativistic orbit with another neutron star, is an exquisite laboratory for which relativistic corrections to Keplerian orbital elements and changes on pulse structure can be measured. In particular, the overall shape of total-intesity pulse profile is changing at a rate of 1% per year. This profile evolution is direct evidence for relativistic precession of the pulsar's spin axis, which leads to a changing view of the two-dimensional beam structure. This current study quantitatively links the observed changes in profile shape to precession through a combination of temporal effects, yielding a precession rate that is in excellent agreement with the value predicted by general relativity. Additional related results are discussed, including constraints on system geometry and potential pulse-beam tomography.

Gallagher, Sarah

Why a Windy Torus?

Mass ejection in the form of winds or jets appears to be as fundamental to quasar activity as accretion, and can be directly observed in many objects with broadened and blue-shifted UV absorption features. A convincing argument for radiation pressure driving this ionized outflow can be made within the dust sublimation radius. Beyond, radiation pressure is still important, but high energy photons from the central engine can now push on dust grains. This physics underlies the dusty wind model for the putative obscuring torus. In our model, the dusty wind is plausibly responsible for providing both the necessary obscuring medium to explain the ratio of broad-to-narrow-line objects and the mid-infrared emission commonly seen in quasar spectral energy distributions.

Cridland, Alex *

Magnetic Helicity Conserved Astrophysical Dynamo

I will present a modification to the mean field theory estimate of the electromotive force found in the equation of motion for large scale magnetic fields. The modification stems from considering the impact that magnetic helicity conservation has on the dynamics of the large scale magnetic fields. The modification suggests how nature gets around the apparent problem with the standard picture of dynamo growth; a back-reaction that either turns off or reverses the dynamo when magnetic helicity is allowed to build up. The theoretical work was worked out by Vishniac & Cho (2001) and will be used as a starting point, although in the present work we are more interested in the effects of the eddy scale magnetic and velocity structure on the modification. I will then present a direct numerical simulation of a shearing box that was used to show a strong correlation between the electromotive force and the modification found by Vishniac & Cho as well as the impact that the eddy scales have on dynamo action. The inverse cascade of magnetic helicity is crucial to our current picture of dynamo growth, and the evolution of the large scale component of the small scale magnetic helicity will be presented. While the code does well to show the validity of this equation, we are restricted in our analysis by numerical resistivity.

Chu, Tony

Hryhoriw, Athena

Magnetic Field in the IV Arch

Faraday rotation of polarized radio emission allows one to derive a mean value for the magnetic field component along the line of sight, provided a measurement of the column density of free electrons (dispersion measure) is available. We use the Schlegel et al. temperature-corrected 100 micron emission as a tracer for total hydrogen column density in the IV arch and subtract the observed HI column density to obtain an estimate for the column density of ionized hydrogen, and find a correlation between this ionized hydrogen excess and rotation measure. The slope of the correlation corresponds with a mean magnetic field component along the line of sight of 1.66 +/- 0.18 microgauss.

Podmore, Hugh

Grain Settling in Circumstellar Disks -- A New Model for Infrared Excess

Circumstellar debris disks around white dwarf stars have been studied extensively using a simple model of a geometrically thin, optically thick disk that is absorbing light from the central star and re-radiating in the infrared. It has been established from observations of silicate emission features that there exists a large number of micron sized grains in these disks that radiate light inefficiently. We find that there may exist a relationship between grain size and orbital height; specifically we theorize that smaller, inefficiently radiating grains will be found at greater distances from the central star than larger, cooler grains. We discuss the motivation for this relationship and demonstrate that this structured distribution of dust grains will raise the temperature profile of the disk above previously determined levels. We use this new result to model the infrared emission from the DAZ white dwarf star GD 56, which is known to harbour circumstellar dust; we achieve an accurate fit to data taken from IRTF, 2MASS and Spitzer and demonstrate that this is not possible using the simple disk model.

Takami, Michihiro

High-Contrast Near-Infrared Imaging Polarimetry of Protoplanetary Disk around RY Tau

We present near-infrared coronagraphic imaging polarimetry of RY Tau. The scattered light in the circumstellar environment was imaged at H-band at a high resolution (∼0".05) for the first time, using Subaru-HiCIAO. The observed polarized intensity (PI) distribution shows a butterfly-like distribution of bright emission with an angular scale similar to the disk observed at millimeter wavelengths. This distribution is offset toward the blueshifted jet. There is faint PI emission on the other side of the disk with a marginal dark lane along the plane of the disk. These features can be explained if the object is associated with a geometrically thick disk or a remnant envelope, and therefore at the earliest stage of the Class II evolutionary phase. We perform comparisons between the observed P I distribution and disk models with: (1) full radiative transfer code, using the spectral energy distribution (SED) to constrain the disk parameters; and (2) monochromatic simulations of scattered light which explore a wide range of parameters space to constrain the disk and dust parameters. The first set of models produces an offset in the PI distribution that is significantly smaller than that observed. The latter produces PI distributions that are close to the observations, but the viewing angle inferred from the best fitting models does not match that inferred by radio interferometry, and shows a significantly larger PI flux than is observed. Following the above inconsistencies between the observations and the disk models, we suggest that the scattered light in the near-infrared is associated with an optically thin and geometrically thick layer above the disk surface, with the surface responsible for the infrared SED. Half of the scattered light and thermal radiation in this layer illuminates the disk surface, and this process may significantly affect the thermal structure of the disk.

Rashedi, Hoda

Relating diffuse interstellar band strengths to line of sight properties

We present an analysis of a set of optical (3770-9000 Å) high resolution (R=80,000) spectra obtained with the HERMES spectrograph mounted on the Mercator telescope for 83 diffuse interstellar band targets representing different interstellar cloud environments. These data were obtained as part of a comprehensive program to study the relation between the observational properties of the DIBs and the physical and chemical characteristics of the interstellar matter in the lines of sight in which the DIB carriers reside. For all targets we have therefore determined the amount of interstellar reddening E(B-V) and measured the strength of several strong and well-known DIBs as well as several atomic and molecular absorption features. We focus in particular on the wavelength range 8470-8740 Å (including the strong DIB at 8620 Å) that will be covered by the upcoming GAIA mission (see http://sci.esa.int/science-e/www/area/index.cfm?fareaid=26). We carried out a very sensitive search for interstellar features in this range by co-adding all available spectra. We investigate how the strength of features in this wavelength range vary as a function of other interstellar parameters (including other DIBs, E(B-V) and atomic and molecular column densities). This study will provide necessary details to use the limited wavelength coverage of GAIA to obtain a comprehensive picture of the properties of the interstellar medium probed by the many millions of stars that GAIA will observe spectroscopically.

Normandeau, Magdalen

Share your teaching tips!

What have you done in your astronomy or astrophysics courses to help your students learn or to pique their interest? Share your astro teaching tips to help us all offer the best courses possible!

Bahramian, Arash *

Discovery of transient X-ray binary Terzan5-X3

Globular clusters (GCs) create X-ray binaries (XRBs) due to stellar interactions in their dense cores. Transient X-ray binaries show short accretion outbursts and long periods of quiescence. Terzan 5 has one of the highest stellar encounter rates of any GC in the Galaxy, with more than 50 X-ray sources, about a dozen quiescent XRBs, and over 30 millisecond radio pulsars (the progeny of XRBs). We identify and study the outburst of a new transient XRB in Terzan 5, the third detected in this GC (thus Terzan5-X3). We use the X-ray instruments Chandra-ACIS, SWIFT-XRT, SWIFT-BAT and MAXI-GSC to perform spectral analyses of the outburst, study a thermonuclear burst, investigate the hard-to-soft spectral state transition, and identify its position and quiescent X-ray counterpart.

Ma, Yin-Zhe

Observing Galaxy clusters with WMAP and Planck

Observations of the cosmic microwave background radiation have become a very successful experiment, since the CMB can not only direct measure the primordial perturbation power spectrum, but also can be used as a backlight to test the large scale structure of the Universe. In this talk, I am going to show to the audience how to study the dynamics of galaxy clusters by using the Sunyaev-Zeldovich effect. We first examine the Sunyaev-Zeldovich effect in the 7-year WMAP data by cross-correlating it with the Planck Early-release Sunyaev-Zeldovich (ESZ) catalogue. With appropriate filtering and stacking analysis, we can find the significance of cluster detections between the two experiment reach excellent agreement. Furthermore, Planck data is able to detect the temperature fluctuation arised from the Sunyaev-Zeldovich effect. With those measurements, one can set up tight constraints on the velocity field of galaxy clusters which can rule out a large class inhomogeneous cosmology models. In the near future, one can use these models to quantify the abundance of baryons in the galaxy clusters and therefore search for the missing baryons in the Universe.