New Photometry and Spectra of AB Doradus C: An Accurate Mass Determination of a Young Low-Mass Object with Theoretical Evolutionary Tracks
Abstract
We present new photometric and spectroscopic measurements for the unique, young, low-mass evolutionary track calibrator AB Dor C. While the new Ks photometry is similar to that we have previously published, the spectral type is found to be much earlier. Based on new H and K IFS spectra of AB Dor C from Thatte et al. (Paper I), we adopt a spectral type of M5.5+/-1.0 for AB Dor C. This is considerably earlier than the M8+/-1 previously estimated by Close et al. and Nielsen et al. yet is consistent with the M6+/-1 independently derived by Luhman & Potter. However, the spectrum presented in Paper I and analyzed here is a significant improvement over any previous spectrum of AB Dor C. We also present new astrometry for the system, which further supports a 0.090+/-0.005 Msolar mass for the system. Once armed with an accurate spectrum and Ks flux, we find L=0.0021+/-0.0005 Lsolar and Teff=2925+170-145 K for AB Dor C. These values are consistent with a ~75 Myr, 0.090+/-0.005 Msolar object like AB Dor C according to the DUSTY evolutionary tracks. Hence, masses can be estimated from the H-R diagram with the DUSTY tracks for young low-mass objects such as AB Dor C. However, we cautiously note that underestimates of the mass from the tracks can occur if one lacks a proper (continuum-preserved) spectrum or is relying on near-infrared fluxes alone.
Based on observations made with ESO telescopes at the Paranal Observatories under program 276.C-5013.- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2007
- DOI:
- 10.1086/518207
- arXiv:
- arXiv:astro-ph/0703564
- Bibcode:
- 2007ApJ...665..736C
- Keywords:
-
- Stars: Binaries: General;
- Instrumentation: Adaptive Optics;
- Stars: Evolution;
- Stars: Formation;
- stars: individual (AB Doradus C);
- Stars: Low-Mass;
- Brown Dwarfs;
- Astrophysics
- E-Print:
- To appear in the July 10, 2007 issue of the ApJ. 21 pages, 8 figures