Mar 1: A Spectral Analysis of the Galactic Bulge Survey X-ray Source CX514

On Mar 1, Christopher Johnson will give us a talk about:

A Spectral Analysis of the Galactic Bulge Survey X-ray Source CX514

The speaker will begin by giving some background information on the Galactic Bulge Survey (GBS) and then focus on one source in particular, CX514. 

Abstract:

We present the spectroscopic and photometric results of the Galactic Bulge Survey (GBS) optical counterpart of the X-ray source CXOGBS J175637.0-271145 (CX514). A refinement of the spectral classification of CX514 has revealed an effective temperature of about 15,000 K and log g = 4.0 which indicates a B6V classification and is unlike the previously labeled B9 classification. A spectroscopic period search of the radial velocity curve revealed a period of 1.3740(61) days which differs from the photometric period found to be 0.8895214(52) days. With the calculation of the dynamic parameters from the radial velocity curve, we find an X-ray source mass of 0.8-0.9 solar masses. This mass constraint, along with the absence of emission in the optical spectra indicates either a white dwarf primary source or an active main sequence type star.

Related paper (not on the exactly same topic, but contains all essential information):

http://arxiv.org/pdf/1211.1040v1.pdf

Speaker: Christopher Johnson

Time: Friday, Mar 1, 11:30AM

Location: Rm 201, Nicholson Hall

Foods and drinks will be provided at 11:30AM.

Feb 22: Identification of 5 Interacting Binaries in the Galactic Bulge Survey

Identification of 5 Interacting Binaries in the Galactic Bulge Survey

We present optical lightcurves, spectroscopy, and classification of five X-ray s ources in the Chandra Galactic Bulge Survey [CXOGBS J174009.1-284725 (CX5), CXOG BS J173935.7-272935 (CX18), CXOGBS J173946.9-271809 (CX28), CXOGBS J173729.1-292 804 (CX37), CXOGBS J174607.6-261547 (CX561)]. These objects were selected based on bright optical counterparts which were quickly found to have emission lines in their optical spectra. This paper presents an illustration of GBS optical follow-up, targeting emission line objects. Of these five objects, four exhibit phot ometric variability in the Sloan $r'$ band. CX5 shows a tentative period of 2.1 hours and is clearly an IP. CX28 and CX37 both exhibit flickering with no clear period. Both are suggested to also be IPs. CX18 was observed to undergo 2 dwarf nova outbursts. Finally, CX561 shows no detectable variability, although its characteristics would be consistent with either a quiescent LMXB or CV.

link to paper

Speaker: Christopher Britt

Time: Friday, Feb 22, 11:30AM

Location: Rm 201, Nicholson Hall

Foods and drinks will be provided.

Journal Club to Resume on Friday

The LA-SIGMA science journal club is going to resume this Friday. The time and location is 11:30AM-12:30PM, Rm 201 (the conference room behind the stairs). Food and drink will be provided.

For this semester, besides the normal 1-hour talks, there will be at least 2 special sessions set aside for APS meeting speakers to practice their talks. March 8 and March 15 will each accomodate 5 speakers who will go to the APS March Meeting. This is a perfect chance for you to rehearse your 10-minute talk. Please sign up with us as soon as possible. We may also have a rehearsal session on Apr 12 for April Meeting participants if people express such need. We also need one or two more speakers for the normal sessions.

 Although the meeting time 11:30AM-12:30PM is currently our best option, it still conflicts with some other activities. If the speaker has an unresolvable schedule conflict, the meeting time may be occasionally changed to 12:30PM-1:30PM. Please be attentive to the time in the notice sent out each week.

Looking forward to seeing you on Friday!