AAO Colloquia

The AAO organises frequent colloquia at our North Ryde headquarters. These are usually held Thursday morning at 11:00 am, though other dates are occasionally scheduled. We welcome talks from visiting astronomers - if you are passing through Sydney and would like to tell us about your work, please contact the AAO colloquium organiser at (colloquia@aao.gov.au). The ATNF (Australia Telescope National Facility) also organises colloquia at their Epping offices. A schedule for these talks can be found on the ATNF Colloquia webpage. The AAO and ATNF occasionally organise Joint Colloquia when the speaker is likely to be of interest to both radio and optical communities. These talks will be found in both the list below, and the ATNF schedule. A list of past speakers can also be found below.

Next Scheduled AAO Colloquium

D. John Hillier, speaking on "Probing the Secrets of Ia Supernovae through their Spectra and Light Curves", to be held in the AAO Meeting Room (Room 7, 1st Floor, Building 2) at 11:00AM on Thursday 6th November, 2014.
Abstract:
The discovery of thousands of supernovae (SNe) by modern survey telescopes is allowing us to define the statistics of SNe occurrence as a function of class and host galaxy properties, and is helping to facilitate the direct identification of SNe progenitors. Further we are identifying SNe for which spectra can be obtained throughout the SN’s temporal evolution.
In this talk we concentrate on Type Ia SNe which are believed to arise from the explosion of a white dwarf (WD) star. Despite the use of SN Ia as cosmological probes many fundamental questions about them remain unanswered. It is still unclear, for example, whether they arise from a WD which explodes when its mass approaches the Chandrasekhar limit, or whether they arise from the merger of two WD stars. No progenitor, or companion star, was detected for the recent SN 2011fe in M101, and this is providing tight limits on SN Ia models. The superb data being obtained for this object are also providing important new constraints and insights.
Utilizing the radiative transfer code CMFGEN, we are undertaking time-dependent radiative transfer calculations of Type Ia SNe that simultaneously compute multi-band light curves and spectra from approximately one day after the explosion through the photospheric phase, and into the nebular phase. The calculations are non-LTE, and allow for a multitude of atomic processes (bound-bound, bound-free, free-free, collisional, and charge exchange), and for non- thermal excitation and ionization from non-thermal electrons created by the degradation in energy of high energy (∼MeV) gamma-rays. We show that standard WD explosion models, with a range of nickel masses, can match observations of Type Ia SNe at maximum. We explore one theoretical model in detail, and show that, except for the earliest times, it provides a reasonable match to the light curve and spectral evolution of the Ia SN 2005cf. However, initial modeling showed large discrepancies with observations, and a good match was only obtained when we used detailed non-LTE modeling, and included all the necessary physics. As the early-time luminosity and spectra evolution are very dependent on the progenitor properties we are also exploring alternate WD explosion models.

 

Upcoming Scheduled Colloquia

DateTimeLocationSpeakerTitle
Thursday 6th November, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)D. John Hillier (University of Pittsburgh )Probing the Secrets of Ia Supernovae through their Spectra and Light Curves
Thursday 13th November, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Jillian Bellovary (Vanderbilt)Scrutinizing the Relationship Between Galaxies and Supermassive Black Holes
Friday 14th November, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Luca Cortese (Swinburne)TBA
Tuesday 18th November, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Michael Childress (ANU)Progenitors of Type Ia Supernovae
Thursday 20th November, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Ricardo Carrera (IAC)The Open Cluster Chemical Abundances from Spanish Observatories survey (OCCASO)

Past Colloquia

DateTimeLocationSpeakerTitle
Thursday 30th October, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Brad Tucker (Australian National Observatory)Results from ESSENCE and the Kepler Extra-Galactic Survey (KEGS)
Tuesday 21st October, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Peter Gillingham and Jeffrey Cooke (AAO and Swinburne)An Australian-led wide-field camera proposal for the Keck Observatory
Friday 17th October, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)David Sanders (IFA Hawaii)The Cosmic Evolution of Luminous and Ultraluminous Infrared Galaxies: New Results from the GOALS and Herschel-COSMOS Surveys
Thursday 9th October, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Esteban Silva-Villa (AAO Visitor)Star clusters, field stars and spiral galaxies
Thursday 2nd October, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Emily Wisnioski (MPE)The KMOS^3D Survey: design, first results, and the evolution of galaxy kinematics
Tuesday 30th September, 201402:00PMAAO Meeting Room (Room 7, 1st Floor, Building 2)Jacinta Delhaize (UWA)Pushing the redshift limit of neutral hydrogen gas observations with spectral stacking
Thursday 4th September, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Cristina Romero-Canizales (Pontificia Universidad Catolica de Chile )The core-collapse supernova rate in luminous infrared galaxies: the case of Arp 299
Tuesday 2nd September, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Aleksandra Hamanowicz, Jonathan St. Antoine, and Samantha Stever (AAO)Undergraduate Winter Student Talks
Tuesday 26th August, 201411:00AMAAO Meeting Room (Room 7, 1st Floor, Building 2)Rosemary Beeston and Connor Diamond (AAO )AAO Undergraduate Winter Students Talks
Wednesday 20th August, 201403:00PMAAO Meeting Room (Room 7, 1st Floor, Building 2)Jonay Isai Gonzalez Hernandez (Instituto de Astrofísica de Canarias (IAC, Canary Islands, Spain))Origin of compact objects and supernovae
Show all past colloquia