The MACHO Project LMC Variable Star Inventory. VIII. The Recent Star Formation History of the Large Magellanic Cloud from the Cepheid Period Distribution

Journal Article · Mon Feb 01 00:00:00 EST 1999 · Astronomical Journal

DOI:https://doi.org/10.1086/300736· OSTI ID:347074

Alcock, C ^[1]; Allsman, R A ^[2]; Alves, D R ^[1]; Axelrod, T S ^[2]; Becker, A C ^[3]; Bennett, D P ^[1]; Bersier, D F ^[2]; Cook, K H ^[1]; Freeman, K C ^[2]; Griest, K; Guern, J A; Lehner, M ^[4]; Marshall, S L ^[1]; Minniti, D ^[1]; Peterson, B A ^[2]; Pratt, M R ^[3]; Quinn, P J ^[5]; Rodgers, A W ^[2]; Stubbs, C W ^[3]; others, and

---

1. Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)
2. Mount Stromlo and Siding Spring Observatories, Australian National University, Weston, ACT 2611 (Australia)
3. Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
4. Department of Physics, University of California at San Diego, La Jolla, CA 92093 (United States)
5. European Southern Observatory, D-85748 Garching bei Muenchen (Germany)

We present an analysis of the period distribution of about 1800 Cepheids in the LMC, based on data obtained by the MACHO microlensing experiment and on a previous catalog by C. H. Payne Gaposchkin. Using stellar evolution and pulsation models, we construct theoretical period-frequency distributions that are compared with the observations. These models reveal that a significant burst of star formation has occurred recently in the LMC ({approximately}1.15thinsp{times}thinsp10{sup 8} yr). We also show that during the last {approximately}10{sup 8} yr, the main center of star formation has been propagating from southeast to northwest along the bar. We find that the evolutionary masses of Cepheids are still smaller than pulsation masses by {approximately}7{percent} and that the red edge of the Cepheid instability strip could be slightly bluer than indicated by theory. There are approximately 600 Cepheids with periods below {approximately}2.5 days that cannot be explained by evolution theory. We suggest that they are anomalous Cepheids and that a number of these stars are double-mode Cepheids. {copyright} {ital {copyright} 1999.} {ital The American Astronomical Society}

• OSTI ID: 347074
• Journal Information: Astronomical Journal, Vol. 117, Issue 2; Other Information: PBD: Feb 1999
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
VARIABLE STARS
MAGELLANIC CLOUDS
CEPHEIDS
STAR EVOLUTION
STAR MODELS
VARIATIONS
MASS
GRAVITATIONAL LENSES