[Alumnos] Charla: LYRAE STARS AS TRACERS OF STELLAR POPULATIONS IN THE GALACTIC BULGE (fwd)

[Secretaria Academica]

El próximo lunes 29 de marzo a las 14:30 hs la Dra. Andrea Kunder dará 
una charla cuyo resumen adjunto.

Quedan todos cordialmente invitados.



RR LYRAE STARS AS TRACERS OF STELLAR POPULATIONS IN THE GALACTIC BULGE

I use a new catalog of Galactic bulge field RR Lyrae variables to explore the 
structure of the Milky Way Galaxy. The catalog contains 3667 RR0 Lyrae stars 
from the eight-year MACHO Project light-curve database. I first use these stars 
to make a reddening map of the central Galactic region. These reddenings are 
based upon my findings that the mean dereddened RR Lyrae color at minimum light 
is (V-R)min,0= 0.28+-0.02 mag, which is determined from new observations of 18 
local RR Lyrae variables as well as 14 RR Lyrae from the literature. Next, I 
find metallicities of the RR Lyrae stars from the Fourier coefficients of their 
light-curves, which are accurate to ~0.2 dex. Hence their absolute magnitudes 
and distances can be found. A correlation between metallicity and 
galactocentric distance is found. For the metal-poor RR0 Lyrae stars ([Fe/H] < 
1.5 dex), the closer a star is to the Galactic center, on average, the more 
metal rich it is. For the metal-rich RR0 Lyrae stars ([Fe/H] > 1.2 dex), this 
trend is reversed. I searched for the evidence of the Galactic bar, and found 
marginal evidence of a bar. This suggests that the RR Lyrae in the bulge 
represent a different population than the majority of the bulge stars, which 
are metal rich and are part of a bar.