BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//ZContent.net//ZapCalLib 1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20180912T103000
DTEND;TZID=Atlantic/Canary:20180912T113000
UID:iactalks-1195
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/1195
CREATED:2018-09-12T10:30:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:On the age of the Milky Way bulge stellar population
DESCRIPTION:On the age of the Milky Way bulge stellar population\nMr. Franc
 isco Surot Madrid\n\nThe Milky Way (MW) galaxy is not much different from 
 its faraway  cousins. However, our position within the MW allows us to stu
 dy the  properties of its stellar populations with exquisite detail in  co
 mparison to extragalactic sources.  The bulge of the MW (i.e. the  st
 ellar population within ~3 kpc from the Galactic center) is the most  mass
 ive stellar component of the MW hosting very old stars (>10 Gyr),  ther
 efore the study of its stellar population properties can shed light  on th
 e formation and evolution of the MW as a whole, and of other  spiral galax
 ies at large.     So far, there is a general consensus on the gl
 obal kinematic,  chemical and structural properties of the bulge populatio
 ns, however the  age, or rather, the distribution of the ages of the stars
  in the bulge  is yet to be completely understood.    We aimed a
 t addressing the questions 'How old is the bulge?' and 'Is  there a spatia
 l age gradient in the bulge?' through the determination of  the stellar ag
 es in the different fields sparsely distributed within a  region of 300 de
 g² centered on the bulge.   We use images from the VISTA Variabl
 es in the Vía Láctea (VVV) survey,  based in near infrared p
 assbands, to extract accurate magnitude and  color of half a billion stars
  in the bulge area using point spread  function fitting.  The newly d
 erived photometric catalogs, used in addition to probe the  extinction tow
 ards the bulge, will be made publicly available to the  entire community. 
 The contribution of the intervening disk population along the bulge  lines
  of sight has been detected and removed by using a statistical  approach i
 n order to obtain a final stars sample that is representative  of the bulg
 e population only. The determination of the stellar ages in different fiel
 ds is provided  through the comparison between the observations and synthe
 tic stellar  population models, which have been carefully tailored to acco
 unt for the  observational effects (i.e. distance dispersion, differential
   reddening, photometric completeness,  photometric and systematic  u
 ncertainties). The simulations leading to the construction of synthetic po
 pulations  have been carried out by using two different methods: i) a mode
 l that  uses a spectroscopically derived metallicity distribution function
 s as  prior, leaving the age as the only free parameter; ii) a genetic  al
 gorithm that finds the best solution within all possible combinations  of 
 age and metallicity (i.e. uniform prior in age and metallicity using  IAC-
 POP/Minniac suite).   We ultimately find that the bulge itself appear
 s to be on average old  (>9.5 Gyr) throughout its extension (|l| < 1
 0° and -10° < b  < +5°), with a mild gradient of about 0
 .16 Gyr/deg towards the  Galactic center.
END:VEVENT
END:VCALENDAR