Astronomy & Physics
Dr. Kanungo's Research Collaboration Receives $1.6 million CFI Grant
|Phil Bennett (adjunct)||Outer atmospheres of cool stars|
|Louise Edwards (adjunct)||Formation and evolution of galaxies|
|Adam Sarty||Electromagnetic properties of nucleon and light nuclei; Teaching methodologies|
|Marcin Sawicki||Observational cosmology; Formation and evolution of galaxies|
|Ian Short||Stellar atmospheres|
|Rob Thacker||Large scale structure and galaxy formation|
|David Turner (emeritus)||Young to intermediate age open clusters and variable stars|
|Gary Welch (emeritus)||Interstellar medium of early-type galaxies|
January 31, 2013, Dr. Chris Geroux, Ph.D.
Congratulations to Dr. Chris Geroux who successfully defended his Ph. D. thesis entitled “The Interaction Between Multi-Dimensional Convection and Radial Stellar Pulsation” on Thursday, January 31. His research was supervised by Dr. Robert Deupree and the external examiner was Dr. Robert Stellingwerf of Stellingwerf Consulting. The other thesis defense committee members were Drs. Luigi Gallo and Ian Short. Chris’ research focused on 1D, 2D, and 3D hydrodynamic simulations of radially pulsating RR Lyrae variables with the objective of computing full amplitude solutions for comparison with observed light curves. Convection, which is believed to limit the pulsational amplitude near the red edge of the RR Lyrae gap, arises naturally in the 2D and 3D calculations without recourse to a phenomenological approach such as the local mixing length theory. A particularly interesting result is that Chris’ light curve for a model near the red edge resembles that of an observed star significantly more closely than do light curves computed with 1D mixing length treatments. Chris is now working as a postdoctoral fellow with Dr. Isabelle Baraffe at the University of Exeter.
January 18th, 2013. David Williamson, Ph.D.
Congratulations to Dr. David Williamson who sucessfully defended his Ph.D. thesis, "The Origin and Evolution of Cold Gaseous Structures in Galaxies and Galactic Outflows" Supervisor Professor Rob Thacker. Committee: Professors Marcin Sawicki, Bob Deupree, and Hugo Martel (Universite Laval).
David's thesis examines the formation and evolution cold gaseous structures in galaxies and galactic outflows in two distinct scenarios. The first investigation details the impact of the collisions between molecular clouds on the overall viscous evolution of galactic disks. Previous analytic estimates suggested the time-scale associated with this process is 1000 Gyr, far in excess of the Hubble time. David showed these calculations are incorrect and numerical results, along with a new analytical approach, show that the viscous time-scale can be shorter than the lifetime of the Universe. The second part of the thesis examines the creation of cold clouds in outflows from modeled Ultra-luminous Infrared Galaxies (ULIRGS). Using adaptive mesh refinement simulations David has shown that 3d simulations can approximately reproduce the key features of absorption lines in these systems, such as line widths. Including sub-grid turbulence models was not found to improve the accuracy of these models and detailed convergence studies will likely be necessary in the future to determine precisely the nature of cold clouds in outflows.
January 14, 2013. Anneya Golob, M.Sc.
December 1, 2012.
Prof. Turner's Work on the North Star Garners International Press
A new distance to the North Star (Polaris) by Saint Mary's Professor David Turner implies that the famed star is 30% nearer than inferred from existing satellite-based measurements. The new distance established for Polaris by Turner and collaborators relies on a high-resolution spectral analysis. “Polaris presents certain anomalies that have so far defied a straightforward interpretation,” noted Dr. Turner. He went on to add that “Our high-resolution spectroscopic observations of Polaris may signal the beginning of a new era in understanding the star.” The research has garnered international press, and has been featured on
A preprint of the article which will appear in the Astrophysical Journal Letters is available here: http://arxiv.org/abs/1211.6103
August 30, 2012. Prof. Kanungo presents at Nobel Symposium
Saint Mary's Professor, Rituparna Kanungo, Astronomy and Physics, attended the 2012 Nobel Symposium, Physics with Radioactive Beams, where she presented a paper, A New Picture of Nuclear Shells. The symposium is a "prestigious, invitation-only event that is part of the Nobel Foundation's Symposium project, which initiates discussions dedicated to areas of science where breakthroughs are occurring or where the topic is of primary cultural or social significance." Dr. Kanungo's presentation explored "the individual character of nuclear isotopes and the shifting of understanding of nuclear shells."
July 7, 2012. Daniel Majaess, Ph.D.
Congratulations to Dr. Dan Majaess who sucessfully defended his Ph.D. thesis, "Constraining the Impact of Metallicity on Cepheid Distances via a Refined Galactic Calibration." Supervisor Professor David Turner. Committee: Professors Phil Bennet, Ian Short, and Tom Barnes (University of Texas).
To paraphase the abstract from Dan's thesis, Dan presented evidence implying that the classical Cepheid VIc period-Wesenheit function is relatively insensitive to metallicity. His results indicate that variations in chemical composition among Cepheids are a comparatively negligible source of uncertainty for VIc Wesenheit-based period-luminosity (PL) relations and extragalactic distances, for determinations of Ho, and for the selection of a cosmological model. His conclusions rest in part on a Galactic classical Cepheid PL calibration that was revised using near-infrared JHKs photometry for new and existing clusters containing Cepheid variables.
May 4, 2012. Jason Sharpe, M.Sc.
Congratulations to Jason Sharpe who successfully defended his M.Sc. thesis, "Design and Construction Elements for Scintillating Fibre Tracking Detectors." Supervisor Professor Adam Sarty. Committee: Professors Robert Singer, Mahbub Khandaker (Norfolk State University), and David Hornidge (Mount Allison University).
Jason's thesis discusses technical issues associated with designing and constructing a scintillating fibre tracker. His results will be directly incorporated into the construction of a scintillating fibre coordinate detector to be built for future experiments at Jefferson Lab's Hall A in Newport News, VA, USA.
In Jason's words: "In many nuclear and particle physics experiments, scientists need to know precise information about a particle, such as the direction it is traveling. A common way to determine this is by using a detector called a scintillating fibre tracker. This detector can determine the path of ionizing particles, a fancy word for any particle that causes electrons to separate from the atom or molecule they are bonded to. The detector relies on a phenomenon called scintillation, which is simply a very fast emission of light after a particle passes through a scintillating fibre. The released light then travels down the fibre to be seen by a light-to-electric converter, to allow scientists to collect information."
Shows normalized light transmission ratios for various optical couplant and fibre-end finish combinations. Optical grease in combination with factory or polished finish provide the highest light transmission efficiency.
March 29, 2012. Patrick Fortier's poster wins top award.
At the annual Applied Science event held at Saint Mary's University, graduate student, Patrick Fortier, was awarded first prize for his poster, "Investigating Exotic Nuclei Through Transfer Reactions at IRIS." Click here to view a copy of his poster.
Patrick is working with Professor Kanungo on an experiment to study weakly bound nuclei, specifically lithium 11, which is a halo nuclei (one neutron in orbit about a core of 3 protons and 7 neutrons). His work takes him to the TRIUMF cyclotron where he is currently testing the ionization chamber, a component of the detector for light and heavy exotic nuclei.
The theoretically predicted kinematics (energy versus scattering angle) will eventually be compared with the results of their experiments.
January 4, 2012. Applying to Our Graduate Program in Astronomy?
Graduate student workshop CASCA 2010 held at Saint Mary's University.
Application forms and procedures can be found at the Faculty of Graduate Studies web site: http://fgsr.smu.ca/grad_pro_app.html. We recommend that you review the information about our Department on this site to first to see if our program is of interest to you. Our graduate program in astronomy is described in detail at: http://www.smu.ca/academic/science/ap/grad.html. The deadline for completed applications receiving highest priority is February 28, 2012, although, we continue to consider applications after that up until we have filled all available slots.
January 5, 2011.
94% Guarantee to get a job with a degree in Astronomy or Astrophysics.
The Wall Street Journal reports that the unemployment level after graduating with an Astronomy or Astrophysics degree is 0% based on a study at Georgetown University. The Georgetown University report actually states the unemployment rate is 6%, still an impressive figure. Click here to link to the WSJ article and here to link to the original study.
September 30, 2011. Liz Arcila Osejo, M.Sc.
Congratulations to Liz Arcila Osejo who successfully defended her M.Sc. thesis, "Star-Forming and Passive Galaxies at z~2 in the CFHT Legacy Survey." Supervisor Professor Marcin Sawicki. Committee: Professors Robert Thacker and Luigi Gallo. Liz has been accepted into the Ph.D. program at SMU.
September 13, 2011. Michael Casey, Dr.
Congratulations to Mike Casey who successfully defended his Ph.D. thesis,
"Analysis of pre-main-sequence delta Scuti stars." Supervisor: Professor David Guenther. External reader: Dr. Konstanze Zwintz (Vienna). Committee: Professors Ian Short and Robert Deupree.
September 9, 2011. Robertson and Beslin Take Top Awards
At this years Undergraduate Mini-symposium (Click here for abstracts), Damien Robertson took first place for his talk on Penning traps (See March 4, 2011 News below) and Wlfried Beslin took second place for his talk on the asteroseismology of rotating stars.
August 3, 2011. Larkin Duelge, M.Sc.
Congratulations to Larken Duelge who successfully defended her M.Sc. thesis, "Deepest Serendipitous Survey of the Intermediate Galactic Latitude from XMM-Newton." Supervisor Professor Luigi Gallo. Committee: Professors Robert Deupree, Ian Short, and Robert Thacker. Larkin has been accepted into the Ph.D. program Sweden.
July 25 , 2011. Jonathon Ramsey, Dr.
Congratulations to Jon Ramsey who successfully defended his Ph.D. thesis, "Into the void: Simulations of protostellar jets from Keplerian." Supervisor Professor David Clarke. Committee: Professors Luigi Gallo, Robert Thacker, and Tom Jones (Minnesota). Jon has taken up a post-doc position at the University of Heidelberg.
July 14, 2011. Professor Luigi Gallo leads Canadian Astro-H astronomers.
Saint Mary's Astronomy & Physics professor Dr. Luigi Gallo has been appointed to lead a team of Canadian scientists working on a Japanese-led space exploration program Astro-H. Astro-H is an X-ray telescope that will probe the physics of black holes and giant clusters of galaxies with an accuracy and precision unparalleled in space telescope history. Dr Gallo and his students will be among the first astronomers to use Astro-H's new high precision instruments. Click here if you want to read more about the Astro-H mission.
Professor Gallo and President Dodds enjoying a moment at the Canadian Astronomical Society meeting held at SMU in 2010.
June 2, 2011. Annual CASCA meeting.
This year's CASCA meeting, held in London Ontario, was attended by Professors Marcin Sawicki (invited presentation) and Robert Thacker (CASCA board), and graduate students Mike Casey (contributed talk) and Bobby Sorba (contributed talk).
Left to right, Mike Casey, Dr. Marcin Sawicki, Bobby Sorba, and Dr. Robert Thacker.
May 26, 2011. Graduate student Dan Majaess receives award.
At the joint AAS/AAVSO meeting in Boston Ph.D. graduate student Dan Majaess was awarded the Chambliss Astronomy Achievement Graduate Student Award for his poster paper "Securing the Distance Scale Via a Universal Wesenheit VI Template and Deep Infrared ZAMS." His research, with Professor David Turner and Dave Lane, involves developing a framework to bolster the precision of the astronomical distance scale, which includes deriving improved distances to nearby galaxies and the center of the Milky Way. Also attending were Dan's supervisor, Professor David Turner, and former SMU astronomy graduate students, Hilding Neilson, Kevin Douglas, Nick MacDonald, and Louise Edwards.
Dan Majaess in front of his poster. (photo courtesy David Turner)
April 11, 2011. Exploring Neutron Rich Isotopes in our Universe.
We are proud to announce that Saint Mary’s University Physics Professor Rituparna Kanungo has been awarded an NSERC-DAS award (Discovery Accelerator Supplements) for $120,000 over three years to study the structure of the nucleus of the atom. The DAS award, to quote the NSERC web site, is given to “researchers who have a well-established research program [which is highly rated in terms of originality and innovation] and who show strong potential to become international leaders in their respective area of research.” The award will supplement her five year NSERC Discovery grant of $500,000.
Dr. Kanungo is studying neutron rich nuclei. The conventional picture of the atom we were taught in school still holds true: the atom is made up of a core, or nucleus, of neutrons and protons surrounded by electrons. The protons have a positive charge that in neutral atoms is balanced by the negative charge of the electrons. Neutrons have about the same mass as protons but do not have any electric charge. So what are the neutrons for? This is exactly the kind of question that Dr. Kanungo is trying to answer by studying some of the most exotic, rule-breaking types of nuclei, nuclei that have an unusually high number of neutrons compared to protons. Neutron rich nuclei are unstable and decay quickly to other more conventional or stable nuclei. As a consequence they have to be created in the laboratory. Dr. Kanungo is using the particle accelerator beams at TRIUMF (Canada’s national laboratory located at UBC in Vancouver) to create and study neutron rich nuclei.
As to why Nature needs neutrons, Dr. Kanungo, explains, “A neutron and a proton together create a bound system. Two protons (or two neutrons) together are not bound. Such is the mystery of the strongest force in nature (the nuclear force), a complete understanding of which remains as one of our major goals in nuclear science. Neutrons being uncharged, can be added on to a positively charged nucleus without much effort (since they do not face Coulomb repulsion) to create heavier isotopes. Nature likely has chosen this path to create most of heavy elements around us like gold, platinum, and uranium, in the core of supernovae, which are a natural site of many neutrons. We are working on creating and understanding the behavior of these neutron-rich nuclei that are unknown to us now.”
The number of neutrons and protons in isotopes of the known elements. The half-life is color coded with light blue corresponding to unstable isotopes and dark red corresponding to stable isotopes.
March 4, 2011. Congratulations to undergraduate Damien Robertson who has been awarded a scholarship to do research at TRIUMF in Vancouver. TRUIMF (originally named Tri University Meson Facility) is a subatomic physics laboratory running a cyclotron particle accelerator.
Damien will be working in the TRIUMF Ion Trap for Atomic and Nuclear Science (TITAN) project. This is a Penning trap facility that traps radioactive ions using a strong magnetic field and a weak electrostatic field to perform precision measurement of its mass. Mass is one of the fundamental properties of a nucleus. High accuracy mass measurements provide information on what are the limits of existence of nuclear isotopes and how does the binding of nucleons change as the isotopes become more neutron-rich. This is one of the important ingredients to understand the nuclear reaction path that creates heavy elements in cores of supernovae. Precise mass measurements can also be used to test theoretical corrections that are used to study the CKM matrix element Vud in search for effects beyond the standard model.
Schematic from TITAN project web site.
February 9, 2011. Dr. Adam Sarty has received one of ten 3M National Teaching Fellowships. Later this year Dr. Sarty will be inducted into the Society for Teaching and Learning in Higher Education.
Dr. Sarty is about to demonstrate that all objects near the earth's surface fall to the ground at the same rate. Everyone knows that a feather and ball bearing will not fall at the same rate but this is because air friction slows the descent of the feather more than the ball bearing. If you compare the rate at which a feather and a ball bearing fall in a vacuum, you will discover that they do indeed fall to the ground at the same rate.
Why is this so? Undergraduate level physics explanation: it's because the inertial force (F=ma) and the gravitational force (GmM/r^2) both depend on the mass of the object, m, and the mass cancels out. Graduate level physics explanation: experiments show inertial mass is equal to gravitational mass to within experimental uncertainties but we do not have a theory of mass and gravity (quantum gravity) that explains why the two should be equal, i.e., we don't know why.
Apollo 15 Commander David Scott dropped a hammer and a feather on the surface of the moon. You can see what happened here.
January 2, 2011. A supernova was discovered by Kathryn Aurora Gray (age 10) using images taken from the Abbey Ridge Observatory (operated by our Department's Astronomy technician, David Lane). Kathryn, daughter of Paul Gray, who, himself has discovered a half-dozen supernova, wanted to follow in her father's footsteps. She spent the fall of 2010 examining a library of practice images looking for the sudden appearance of a new star. Then in the new year began looking at current images.
Kathryn at her computer comparing star fields taken at different times. (photo courtesy Paul Gray).
Supernova are not new stars but, in fact, old stars, nearing the end of their nuclear burning life. In a final burst, the star ignites enough nuclear fuel in its core that the resultant wave of energy blows away the outer layers of the star (in some cases forming a ring nebula). In the night sky, an anonymous and faint star, will suddenly appear. Kathryn's supernova (also known as Supernova 2010lt) is far too faint to be seen by the naked eye. Her supernova (mag ~17) appeared in the galaxy UGC 3378 (mag 15). Supernova are extremely important to astronomers. They are used to measure distances to distant galaxies and are, as a consequence, central to the debate on the existence of Dark Energy.
The fuzzy blob near the center of the image is the galaxy UGC 3378. The dot flashing on and off next to it is the supernova. The above animated photo shows the region of the sky before the star went supernova (the star is too faint to see) and then just after. The supernova is almost as bright as the galaxy (which itself is as bright as 100,000,000,000 stars!).
For more information check out the following links:
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June 6, 2013 Room SB160 12:00-1:00pm
Dr. Travis Metcalfe
Space Science Institute, Boulder
Magnetic Activity Cycles and the Solar-Stellar Connection
Observations of magnetic activity cycles in other stars provide a broader context for our understanding of the 11-year sunspot cycle. The discovery of short activity cycles in a few stars, and the recognition of analogous variability in the Sun, suggest that there may be two distinct dynamos operating in different regions of the interior. Consequently, there is a natural link between studies of magnetic activity and seismology, which can characterize some of the internal properties that are relevant to dynamos. I will provide an historical overview of the connection between these two fields and I will discuss how recent observations of the young solar analog epsilon Eridani might teach us something useful about the rotational history of our own Sun.
Journal Club AT305
Friday, June 7, 2013
Room AT305, 10:30-11:00.