WFPC2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group

Details WFPC2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group WFPC2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group

1998-05-20

arxiv.org/abs/astro-ph/9805268v1

Astron.J. 116 (1998) 1244-1262

Astronomy and Astrophysics

Astrophysics

64 pages, 18 figures, 4 tables accepted for publication in the Astronomical Journal (Sept. 98)

Scientific paper

10.1086/300515

The unprecedented detail of the WFPC2 colour-magnitude diagrams of the resolved stellar population of Leo A presented here allows us to determine a new distance and an accurate star formation history for this extremely metal-poor Local Group dwarf irregular galaxy. From the position of the red clump, the helium-burning blue loops and the tip of the red giant branch, we obtain a distance modulus, m-M=24.2+/-0.2, or 690 +/- 60 kpc, which places Leo A firmly within the Local Group. Our interpretation of these features in the WFPC2 CMDs at this new distance based upon extremely low metallicity (Z=0.0004) theoretical stellar evolution models suggests that this galaxy is predominantly young, i.e. <2 Gyr old. A major episode of star formation 900 - 1500 Gyr ago can explain the red clump luminosity and also fits in with our interpretation of the number of anomalous Cepheid variable stars seen in this galaxy. We cannot rule out the presence of an older, underlying globular cluster age stellar population with these data. However, using the currently available stellar evolution models, it would appear that such an older population is limited to no more than 10% of the total star formation to have occured in this galaxy. Leo A provides a nearby laboratory for studying young metal poor stars and investigations of metal-poor galaxy evolution, such as is supposed to occur for larger systems at intermediate and high redshifts.

Affiliated with

Also associated with

No associations

Rating

WFPC2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group 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 WFPC2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and WFPC2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-497996