YCAA Logo
YCAA Logo
The Crab Nebula in Blue and White Credit & Copyright: Jay Gallagher (U. Wisc.),
The Crab Nebula in Blue and White Credit & Copyright: Jay Gallagher (U. Wisc.),
Interstellar Dust-Bunnies of NGC 891 Credit: C. Howk & B. Savage (Wisconsin);
Interstellar Dust-Bunnies of NGC 891 Credit: C. Howk & B. Savage (Wisconsin);
Hubble. Credit: R. Williams (STScI), the Hubble Deep Field-South Team, and NASA
Hubble. Credit: R. Williams (STScI), the Hubble Deep Field-South Team, and NASA
Dumbell. Credit & (c): Michael Pierce (Indiana U.) et al., WIYN, AURA, NOAO, NSF
Dumbell. Credit & (c): Michael Pierce (Indiana U.) et al., WIYN, AURA, NOAO, NSF
Abell 39.    (c): George Jacoby (WIYN Obs.) et al., WIYN, AURA, NOAO, NSF
Abell 39. (c): George Jacoby (WIYN Obs.) et al., WIYN, AURA, NOAO, NSF
Bubbling. Credit: Jeffrey Kenney (Yale) et al., WFPC2, HST NASA
Bubbling. Credit: Jeffrey Kenney (Yale) et al., WFPC2, HST NASA

Mailing Address

Yale Center for Astronomy and Astrophysics
Physics Department
P.O. Box 208120
New Haven, CT 06520-8120

Campus Address

260 Whitney Avenue
454 J.W. Gibbs Laboratory

Telephone: (203) 432-3392

Fax: 203) 432-3824

E-mail: ycaa@yale.edu

Upcoming YCAA Seminars

Syndicate content
Updated: 5 hours 29 min ago

YCAA seminar Lynne Hillenbrand, Caltech Title: "The Young and the Restless Stars" - Tue, April 22, 2014

5 hours 29 min ago
When: Tuesday, April 22, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm oustide the auditorium, 3rd floor BASS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Professor Lynne Hillenbrand

Description: Abstract: Young stars associated with regions of recent and ongoing star formation are amenable to study across almost the entire electromagnetic spectrum. Furthermore, they are enigmatically variable over much of this range -- due to processes occurring in the inner circumstellar disk, the disk-to-star accretion zone, and perhaps the outflow regions. The talk will give an overview of the relevant phenomena and present several types of state-of-the-art multiwavelength time domain data sets along with their physical interpretation.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA Seminar Tabetha Boyajian, Yale University, Title: "Sizing up the Stars" - Tue, April 15, 2014

Tue, 04/15/2014 - 4:46am
When: Tuesday, April 15, 2014 2:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the auditorium on the 3rd floor BAS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Tabetha Boyajian, Yale University Astronomy Dept.

Description: Abstract: I will discuss results associated with ongoing surveys to measure diameters and temperatures of main sequence stars with long-baseline optical/infrared interferometry. I will demonstrate how such empirical data are used to construct and calibrate less-direct relationships in order to extend our knowledge to a large number of stars. This analysis includes relations linking color-temperature/radius/luminosity, surface brightness, as well as the global physical properties of temperature-radius-luminosity. The data are also used to identify weaknesses in stellar atmosphere and evolutionary modeling, where observed discrepancies with models compared to observations have implications for the characterization of exoplanet systems. Lastly, I will introduce a Breaking B.A.D. method, where we provide empirical constraints to spectroscopic modeling in order to improve their accuracy and to aid in the development of new models.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA seminar Carey Lisse, Johns Hopkins University Title: "Initial Results From the Comet ISON Observing Campaign (CIOC)" - Tue, April 8, 2014

Tue, 04/08/2014 - 5:00am
When: Tuesday, April 8, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the auditorium on the 3rd floor BASS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Sr. Research Scientist Carey Lisse

Description: Abstract: In 2012 - 2013 Comet ISON flew through the inner solar system as predicted, coming within 0.07 AU of Mars, 0.24 AU of Mercury, and 10^6 km of the solar photospheric surface. It did not become the “Comet of the Century” in terms of its brightness in the Earth’s nighttime sky as pre-dicted, but instead became one of the rare dynamically new Oort Cloud comets to graze the Sun’s corona (the-se occur every few decades; the last one observed was C/Ikeya-Seki 1965). For an initially bright comet detected as far out as the orbit of Saturn in Sept 2011, the comet worried us all quite a bit with its flatlining activity from 4 to 0.8 AU (March to Oct 2013). It thus put on a somewhat disappointing showing at Mars in early October 2013, but then defied predictions of its demise and a government shutdown, ramping up instead to become a beautiful early morning green “lollipop” as it passed Mercury in mid-November. ISON ultimately peaked at a gas production rate maximum of ~ 2 x 10^30 mol/sec of water within the last few days before perihelion, then seemed to have almost no gas output the day of perihelion before spectacularly disrupting under the watchful eyes of the SOHO and STEREO spacecraft on Thanksgiving Day, 28 Nov 2013, after which its debris fan was tracked for days until it finally disappeared. Throughout this time, parallels to the behavior of other dynamically new comets, like C/1973 E (Kohoutek), were readily apparent.

In this talk I present an overview of the observing results and cometary behavior found for C/2012 S1 (ISON) during its 2012 – 2013 apparition. I will also present a list of initiatives tried and lessons learned from the coordinated Comet ISON Observing Campaign (CIOC), including the use of modern digital era resources, that could be applied to future comet observing campaigns, e.g. the upcoming Comet Siding Spring and ROSETTA campaigns of 2014.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA seminar Ashley Pagnotta, American Museum of Natural History, "The Local Type Ia Supernova Progenitors" - Tue, April 1, 2014

Tue, 04/01/2014 - 4:55am
When: Tuesday, April 1, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the auditorium on the 3rd floor hallway
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Ashley Pagnotta

Description: Abstract:Although the basic mechanism responsible for Type Ia supernovae appears to be well understood (thermonuclear explosion of a carbon-oxygen white dwarf that has reached the Chandrasekhar mass limit), the identity of the progenitor system(s) remains a mystery. With implications from stellar evolution to frontline cosmology, it is critical to attack this problem from every possible angle. I will present results from our study of four known historical Ia supernovae in the Large Magellanic Cloud (LMC). We used archival Hubble Space Telescope images of SNR 0509-67.5 and SNR 0519-69.0 as well as Gemini images of SNR 0505-67.9 and SNR 0509-68.7 to determine the site of each explosion and then search the surrounding area for potential ex-companion stars that were left behind. The search was carried out within an error ellipse that accounts for measurement error on the geometric center of the remnant, the orbital velocity of the pre-supernova binary system, and kicks from the actual explosion. For SNR 0509-67.5, the error ellipse is empty to the HST 5-sigma limiting magnitude of V=26.9. Using an LMC distance modulus of 18.5, this implies that any single degenerate ex-companion must be fainter than M_V=+8.4 (corresponding approximately to a K9 main sequence star), which eliminates all currently-published single-degenerate models and leads us to conclude that this system had a double-degenerate (double white dwarf) progenitor. For the other three LMC Ia SNRs, we find potential single-degenerate ex-companions which need further study, but may end up reinforcing current theories indicating there should be multiple progenitor channels.

Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA seminar, Saskia Hekker, Max Planck Institute, Title: Towards Accurate Ages of Stars using Asteroseismology - Tue, March 25, 2014

Tue, 03/25/2014 - 4:47am
When: Tuesday, March 25, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served outside the auditorium on the 3rd floor BASS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Saskia Hekker

Description: Abstract: Over the past decade asteroseismology -- the study of internal structures of stars through their global oscillations -- has leaped forward thanks to the space borne telescopes CoRoT and Kepler. These satellites have provided photometric timeseries data of unprecedented quality for hundreds of low-mass main-sequence stars and tens of thousands of red-giant stars. In this presentation, I will discuss (some of) the groundbreaking discoveries made over the past decade and provide prospects to use asteroseismology to determine accurate ages of stars.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA seminar, Jennifer Lotz, Space Telescope Science Institute Title: "The Frontier Fields and Beyond" - Tue, March 4, 2014

Tue, 03/04/2014 - 5:51am
When: Tuesday, March 4, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the auditorium on the 3rd floor BASS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Jennifer Lotz

Description: Abstract: How deep can we go? What are the faintest and most distant galaxies we can see with the Hubble Space Telescope now, before the launch of the James Webb Space Telescope?

This is the challenge taken up by the Frontier Fields, a new director's discretionary time campaign with HST and the Spitzer Space Telescope to see deeper into the universe than ever before. The Frontier Fields will combine the power of HST with the natural gravitational telescopes of high-magnification clusters of galaxies to produce the deepest observations of clusters and their lensed galaxies ever obtained. These observations will reveal distant galaxy populations ~10-100 times fainter than any previously observed, allowing astronomers to study the early progenitors of the Milky Way and the faint galaxies responsible for reionization. I will review the prospects for studying galaxies at cosmic dawn with JWST, extremely large ground-based telescopes such as the Thirty Meter Telescope and Giant Magellan Telescope, and future space missions over the next decade and beyond.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA seminar, Steffen Mieske, European Southern Observatory,Chile Title:Ultra compact dwarfs and the star cluster - galaxy interface - Tue, February 25, 2014

Tue, 02/25/2014 - 6:15am
When: Tuesday, February 25, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the auditorium on the 3rd floor BASS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Steffen Mieske, ESO

Description: Abstract:I will review the properties of ultra-compact dwarf galaxies (UCDs), a
class of stellar systems covering the parameter space between
omega Centauri and M32. They are believed to be either the most
massive star clusters in the universe, or tidally truncated galaxies,
or, both. In the talk I will focus mostly on two aspects:

1. The specific frequencies of UCDs - a recently introduced quantity
that allows to test whether the luminosity distribution of UCDs
follows the bright tail of the globular cluster luminosity function.

2. The elevated dynamical M/L ratios of UCDs. Are they due to a
variation of the IMF, or, due to supermassive central black holes as
relics of their galaxian nature, or, dark matter? In this context I
report on recently started adaptive optics spectroscopy campaigns
targetting UCDs in which we aim at resolving their internal dynamics.

I will conclude the talk with a discussion on whether the biggest star
clusters in the Milky Way are in reality galaxies.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA seminar Kanani Lee, Yale Geology Title:Sinking deep in to a carbon-rich planet: Using experiments to constrain planetary interiors - Tue, February 18, 2014

Tue, 02/18/2014 - 6:26am
When: Tuesday, February 18, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the auditorium on the 3rd floor BASS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Kanani Lee, Yale Geology Dept.

Description: Abstract: The recent detection of carbon-rich atmospheres of exoplanets and the plausibility of C-rich interiors, lends itself easily to the discussion of what a C-rich interior might look like and how it may behave. With no Solar System analog and few data, there's much to be learned about how a C-rich planet might evolve. Using new experimental measurements of melting silicon carbide SiC at high pressures, we propose a novel thermochemically evolved planet.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA seminar Seth Redfield, Wesleyan University Title: "Exoplanet Atmospheres and Stellar Astropheres" - Tue, February 11, 2014

Tue, 02/11/2014 - 2:02pm
When: Tuesday, February 11, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the auditorium on the 3rd floor BASS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Seth Redfield

Description: Abstract: The number of exoplanets with detected atmospheres is rapidly increasing. Exoplanet atmospheres present an intriguing opportunity to evaluate planetary habitability, and a critical component of that evaluation will be the unique properties of the host star. I will present recent observations of an extended exoplanet atmosphere, revealed by the first detection of H-alpha absorption in the transmission spectrum of the transiting exoplanet, HD189733b. The mechanism for causing such an extended atmosphere is almost certainly tied to the electromagnetic radiation and particle wind of the host star. While main sequence low-mass stars have relatively weak winds that are difficult to detect directly, such measurements are critical for understanding the planetary atmospheres in the system. I will review a technique to measure the mass loss rate of a solar like star by detecting its astrosphere, or the interface between the stellar wind and the surrounding interstellar medium, an analogy with the heliosphere which surrounds our own solar system. I will discuss a recent Hubble program to search for astrospheres in several nearby stars, including some that host their own planetary systems.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA seminar Hans Moritz Guenther CfA, Harvard University Title:Accretion, Winds and Jets: High-Energy Emission from Young Stars - Tue, February 4, 2014

Tue, 02/04/2014 - 5:49am
When: Tuesday, February 4, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the auditorium 305 BASS
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Hans Guenther

Description: Abstract:I will review the most energetic phenomena observed from young stars: X-rays and FUV emission are powered by accretion onto the star, wind shocks and jet shocks. The high-energy photons potentially impact the properties of dust and gas in the accretion disk and the surrounding nebula. Young stars generate energy by accretion in addition to the intrinsic energy production in the interior that is present in all stars. This energy is released in spatially and temporally variable accretion spots on the stellar surface. A fraction of it is radiated away as X-rays, while the rest influences the chromosphere and the stellar activity by radiation transfer or magnetic and hydrodynamic forces. The resulting radiation and outflows (winds and collimated jets) provide a strong feedback on the proto-planetary disk and the parent molecular cloud.

I will present observations from T Tauri stars and their more massive brethren, the HAeBe stars, which are performed with Chandra, XMM-Newton and HST and discuss how relatively simple models of the accretion shock explain most of the observed spectral and photometric properties.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA Seminar Jenny Greene, Princeton University Title: To Build an Elliptical Galaxy - Tue, January 28, 2014

Tue, 01/28/2014 - 5:44am
When: Tuesday, January 28, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside the 305 BASS hallway
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Jenny Greene

Description: Abstract: I discuss two essential aspects of elliptical galaxy formation: how
they get their stars, and how they lose their gas. For the former, I
use integral-field observations of local massive galaxies to study the
stellar populations and kinematics of stars at large radius, to
understand the origin of the size growth of elliptical galaxies. Then
I focus on black hole feedback as a means of clearing gas from massive
galaxies. I show that luminous obscured quasars have ubiquitous,
round ionized outflows with very high gas dispersions of nearly 1000
km/s out to 20 kpc. Finally, if time permits I will combine these two
themes and present our recent search for sub-pc supermassive black
hole binaries.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA Seminar Sarah Ballard, University of Washington Title: Kepler-93b: The Most Precisely Measured Radius Outside the Solar System - Tue, January 21, 2014

Tue, 01/21/2014 - 5:49am
When: Tuesday, January 21, 2014 2:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served at 2:00pm outside of 305 BASS hallway
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Sarah Ballard

Description: I will present a study of Kepler-93b, a 1.5 R_Earth transiting planet around one of the brightest Kepler exoplanet host stars. The wealth of short cadence data for Kepler-93 enable an asteroseismic characterization of the star, making it one of the smallest stars for which such a measurement is possible. The stellar density inferred from the standing waves within the star matches the density independently inferred from the exquisite Kepler transit light curve, lending credence to the planetary interpretation of the signal. The transit depth and stellar radius are determined with such precision that they render Kepler-93b the best-measured planet orbiting a star other than the Sun: its radius is known to within 120 km. The brightness of the host star Kepler-93 also made it an ideal target to test a new observing mode with the Spitzer Space Telescope, which gathered a wealth of seven transits of the planet.

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu
   

YCAA Seminar Richard Scalzo, Australia National University Title:Inferring the Mass of Type Ia Supernova Progenitors - Tue, January 14, 2014

Tue, 01/14/2014 - 6:09am
When: Tuesday, January 14, 2014 2:30 PM - 3:30 PM
Where:
   Bass Center for Molecular and Structural Biology (BASS), 305 BASS
   266 Whitney Ave., New Haven, CT 06511
   (Location is wheelchair accessible)
   Tea will be served outside the 305 BASS hallway at 2:00pm
Tags: astrophysics, science, seminar, talk

Speaker/Performer: Richard Scalzo

Description: Abstract:Type Ia supernovae, the thermonuclear explosions of carbon-oxygen white dwarfs, have been used for over a decade as precision tools for studying the expansion history of the universe. However, the evolutionary pathways to supernova explosion and the physics of the explosion remain uncertain.
The total mass ejected in the explosion is a powerful discriminant between different theoretical explosion scenarios. The bolometric light curve of a SN Ia is sensitive to the ejected mass, and moreover can be reliably modeled using simple semi-analytic techniques. I will discuss my ongoing work on testing SN Ia progenitor scenarios using real SN Ia bolometric light curves from the Nearby Supernova Factory (SNfactory) survey.
Although the model I use is currently tuned for SNe Ia, it can be extended for use on any supernova with a light curve powered by radioactive decay, including type Ib/c supernovae (explosions of massive stars, associated with gamma-ray bursts) and pair-instability supernovae (theoretical explosions of very massive stars).

Open To: General Public
Contact Information:
   Laurelyn Celone
   
   laurelyn.celone@yale.edu