IRC-10443: a Multi-Periodic SRa Variable and the Nature of Long Secondary Periods in AGB Stars
Abstract
We obtained BVIC photometry of IRC-10443 on 85 different nights distributed over two years, and low resolution absolute spectro-photometry and high resolution Echelle spectroscopy. Our data show that IRC-10443, which was never studied before in detail, is an SRa variable, characterized by Δ B = 1.27, Δ V = 1.14 and Δ I = 0.70 mag amplitudes and mean values <B> = 13.75, <V> = 11.33 and <IC> = 6.18 mag. Two strong periodicities are simultaneously present: a principal one of 85.5 (±0.2) days, and a secondary one of 620 (±15) days, both sinusoidal in shape, and with semi-amplitudes Δ V = 0.41 and 0.20 mag, respectively. We find that IRC-10443 is an M7 III star, with a mean heliocentric radial velocity -28 km/s and reddened by EB-V = 0.87, a 1/3 of which of circumstellar origin. The same 0.5 kpc distance is derived from application of the appropriate period-luminosity relations to both the principal and the secondary periods. The long secondary period causes a sinusoidal variation of 0.13 mag semi-amplitude in the V-IC color, with the star being bluest at maximum and reddest at minimum, and with the associated changes in effective temperature and radius of 85 K and 6%, respectively. This behavior of colors argues in favor of a pulsation nature of the still mysterious long secondary periods in AGB stars.
- Publication:
-
Baltic Astronomy
- Pub Date:
- 2008
- DOI:
- 10.48550/arXiv.0810.1375
- arXiv:
- arXiv:0810.1375
- Bibcode:
- 2008BaltA..17..223M
- Keywords:
-
- stars: pulsations;
- stars: AGB;
- stars: variables: individual (IRC--10443);
- Astrophysics
- E-Print:
- Published in Baltic Astronomy, vol. 17, pag. 223-234 (2008)