2008BaltA..17..223M -
Baltic Astronomy, 17, 223-234 (2008/August-0)
IRC-10443: A multi-periodic sra variable and the nature of long secondary periods in AGB stars.
MUNARI U., SIVIERO A., OCHNER P., DALLAPORTA S. and SIMONCELLI C.
Abstract (from CDS):
We obtained BVIC photometry of IRC-10443 on 85 different nights distributed over two years, and low resolution absolute spectrophotometry and high resolution Echelle spectroscopy. Our data show that IRC-10443, which was never studied before in detail, is an SRa variable, characterized by ΔB = 1.27, ΔV = 1.14 and ΔI = 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 ΔV = 0.41 and 0.20 mag, respectively. We find that IRC-10443 is an M7III 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.
Abstract Copyright:
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Journal keyword(s):
stars: pulsations - stars: AGB - stars: variables: individual: IRC-10443
Simbad objects:
4
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