Properties of RR Lyrae stars in the Inner Regions of the Large Magellanic Cloud

Journal Article · Thu May 27 04:00:00 EDT 2004 · Astronomy and Astrophysics

DOI:https://doi.org/10.1051/0004-6361:20034494· OSTI ID:15014164

Borissova, J; Minniti, D; Rejkuba, M; Alves, D; Cook, K H; Freeman, K C

We present the radial velocities, metallicities and the K-band magnitudes of 74 RR Lyrae stars in the inner regions of the LMC. The intermediated resolution spectra and the infrared images were obtained with FORS1 at the ESO VLT and with the SOFI infrared imager at the ESO NTT. The best 43 RR Lyrae with measured velocities yield an observed velocity dispersion of {sigma}=61{+-} 7 km s{sup -1}. We obtain a true LMC RR Lyrae velocity dispersion of {sigma}=53 km s{sup -1}, which is higher than the velocity dispersion of any other LMC population previously measured. This is the first empirical evidence for a kinematically hot, metal-poor halo in the LMC as discussed in Minniti et al. (2003). Using Layden's (1994) modification for the {Delta}S method we measured the metallicity for 23 of our stars. The mean value is [Fe/H]=-1.46{+-}0.09 dex. The absolute magnitudes M{sub v} and M{sub K} of RR Lyrae stars are linear functions of metallicity. In the V band, our data agree with the Olech et al. (2003) relation, in the K band the slope is flatter. The average apparent V luminosity of 70 RR Lyrae stars is <V>=19.45{+-}0.04 and the average K luminosity of 37 RR Lyrae stars is <K>=18.20{+-}0.06. There is no obvious relation between apparent V magnitude and LogP, while the RR Lyrae K band magnitudes show a well defined linear trend with LogP. Using the Bono et al. (2001) and Bono et al. (2003) theoretical Near-Infrared Period-Luminosity-Metallicity relations we calculate the LMC distance modulus {mu}{omicron}=18.48{+-}0.08.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 15014164
• Report Number(s): UCRL-JRNL-205052
• Journal Information: Astronomy and Astrophysics, Journal Name: Astronomy and Astrophysics Journal Issue: 423 Vol. 423; ISSN AAEJAF; ISSN 0004-6361
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
LUMINOSITY
MAGELLANIC CLOUDS
MODIFICATIONS
RESOLUTION
SPECTRA
STARS
VELOCITY