HD 81410: a new RS CVn binary

Abstract. This is the third paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. High resolution echelle spectra including all the optical chromospheric activity indicators from the Ca ii H & K to Ca ii IRT lines are analysed here for 16 systems. The chromospheric contribution in these lines has been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted Hα profile of the very active star HU Vir. These profiles are well matched using a two-component Gaussian fit (narrow and broad) and the broad component can be interpreted as arising from microflaring. Red-shifted absorption features in the Hα line have been detected in several systems and excess emission in the blue wing of FG UMa was also detected. These features indicate that several dynamical processes, or a combination of them, may be involved. Using the E Hα /E Hβ ratio as a diagnostic we have detected prominence-like extended material viewed off the limb in many stars of the sample, and prominences viewed against the disk at some orbital phases in the dwarfs OU Gem and BF Lyn. The He i D 3 line has been detected as an absorption feature in mainly all the giants of the sample. Total filling-in of the He i D 3 , probably due to microflaring activity, is observed in HU Vir. Self-absorption with red asymmetry is detected in the Ca ii H & K lines of the giants 12 Cam, FG UMa and BM CVn. All the stars analysed show clear filled-in Ca ii IRT lines or even notable emission reversal. The small values of the E 8542 /E 8498 ratio we have found indicate Ca ii IRT emission arises from plage-like regions. Orbital phase modulation of the chromospheric emission has been detected in some systems, in the case of HU Vir evidence of an active longitude area has been found.

“…The 12.86833-day photometric period derived by Raveendran et al (1982) is very close to the orbital period. It was found to be an X-ray source and a microwave emitter (Mitrou et al 1996).…”

Section: Il Hya (Hd 81410)supporting

confidence: 60%

Multiwavelength optical observations of chromospherically active binary systems

Montes

Fernández-Figueroa

Castro

et al. 2000

“…interval and are shown in Fig. 6, where phases are reckoned from the 12.86833-day orbital period computed by Raveendran et al (1982). The V-band light curve is double-peaked and very clear color variations, showing the star redder at both light minima, are present.…”

Section: Resultsmentioning

confidence: 99%

Long-term monitoring of active stars

Cutispoto

1998

Abstract. In the framework of an extensive program focusing on the global properties and evolution of active stars, high-precision UBV (RI) c photometry of 19 selected stars, collected at the European Southern Observatory over the 15-31 March 1991 interval is presented. Significant evolution of the light curves, period variations and evidence for long-term variability of the global degree of spottedness are found. Most of the spectral classifications are discussed. A flare event was detected for the star HD 127535 = V 841 Cen. These observations contribute to the establishment of a time-extended photometric database which can give important clues on topics such as the stability of spotted areas, differential rotation, solar-like cycles and the correlation between inhomogeneities at different atmospheric levels 1 .

“…From additional photometry Raveendran et al (1982) discovered that a period of 12.86833 satisfied all available photometry and identified the star as an RS CVn binary. Combining 25 years of V -band photometry, Strassmeier et al (1997) obtained a long-term average period of 12.7864 days.…”

Section: Brief Historymentioning

confidence: 95%

Orbital elements and physical parameters of ten chromospherically active binary stars

Fekel¹,

Strassmeier

Weber

et al. 1999

Abstract. Orbital elements have been determined for 10 chromospherically active binaries from a combination of new velocities and velocities in the literature. First orbits for three binaries, HD 33363, HD 152178, and HD 208472, are presented, as well as updated orbits for seven other binaries. Two of the latter systems, LN Peg and HD 106225 were discovered to be triple, and both short-and longperiod orbits have been computed for each. Fundamental properties have been determined for the chromopherically active primary in each system.