Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-02-20
Astron.J.123:3154-3198,2002
Astronomy and Astrophysics
Astrophysics
46 pages, 12 figures Accepted by AJ
Scientific paper
10.1086/340356
We present the results of a search for short-period variable stars in Leo A. We have found 92 candidate variables, including eight candidate RR Lyrae stars. From the RR Lyraes, we measure a distance modulus of (m-M)_0 = 24.51 +/- 0.12, or 0.80 +/- 0.04 Mpc. This discovery of RR Lyraes confirms, for the first time, the presence of an ancient (> ~11 Gyr) population in Leo A accounting for at least 0.1% of the galaxy's V luminosity. We have also discovered a halo of old (> ~2 Gyr) stars surrounding Leo A, with a scale length roughly 50% larger than that of the dominant young population. We also report the discovery of a large population of Cepheids in Leo A. The median absolute magnitude of our Cepheid sample is M_V = -1.1, fainter than 96% of SMC and 99% of LMC Cepheids. Their periods are also unusual, with three Cepheids that are deduced to be pulsating in the fundamental mode having periods of under 1 day. Upon examination, these characteristics of the Leo A Cepheid population appear to be a natural extension of the classical Cepheid period-luminosity relations to low metallicity, rather than being indicative of a large population of ``anomalous'' Cepheids. We demonstrate that the periods and luminosities are consistent with the expected values of low-metallicity blue helium-burning stars (BHeBs), which populate the instability strip at lower luminosities than do higher-metallicity BHeBs.
Claver Jennifer
Cole Andrew A.
Dohm-Palmer Robbie C.
Dolphin Andrew E.
Gallagher Jay S.
No associations
LandOfFree
Variable Stars in Leo A: RR Lyraes, Short-period Cepheids, and Implications on Stellar Content does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Variable Stars in Leo A: RR Lyraes, Short-period Cepheids, and Implications on Stellar Content, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Variable Stars in Leo A: RR Lyraes, Short-period Cepheids, and Implications on Stellar Content will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-539447