Topic
Semiregular variable star
About: Semiregular variable star is a research topic. Over the lifetime, 8 publications have been published within this topic receiving 25 citations.
Papers
1 Jan 1993
TL;DR: RX Bootis as discussed by the authors is an SRb-type semiregular variable star of spectral type M6.5eM8e, varying optically between mpg=8.6 and 11.3 mag (Khopolov et al., 1985).
Abstract: RX Bootis is an SRb-type semiregular variable star of spectral type M6.5eM8e, varying optically between mpg=8.6 and 11.3 mag (Khopolov et al., 1985). The star loses mass at a rate of 4-10 -7 M6}/yr creating a circumstellar shell expanding with a final velocity of-11.5 km---ls(Gehrz and Woolf, 1971; Knapp and Morris, 1985). The shell contains a strong 22 GHz H20 maser, which occasionally reaches peak flux densities of several hundred Jansky (Engels et al. 1988 and ref. therein), making RX Boo an outstanding case to study the water maser properties in semiregular variables. Additionally the shell sustains an SiO maser, but no' OH maser emission (Benson et al., 1990). The stellar radial velocity is +0.5-1.0 km s "1 (Knapp and Morris, 1985; Bujarrabal et al. 1986), and the distance is 225 pc (Morris et al. 1979).
3 citations
TL;DR: In this paper, a red semiregular variable star with an amplitude of its V-band brightness variations of ≈2m was observed with the 2.5m telescope at the Caucasian Observatory of the Sternberg Astronomical Institute of the Moscow State University using differential speckle polarimetry at wavelengths of 550, 625, and 880 nm.
Abstract: V CVn is a red semiregular variable star with an amplitude of its V-band brightness variations of ≈2m. An unusually high amplitude of its polarization variability, up to 6%, a noticeable inverse correlation between polarization and total flux, and relative constancy of the angle of polarization distinguish this star from other semiregular variables. To clarify the nature of these peculiarities, we have observed the object with the 2.5-m telescope at the Caucasian Observatory of the Sternberg Astronomical Institute of the Moscow State University using differential speckle polarimetry at wavelengths of 550, 625, and 880 nm. The observations were performed on 20 dates distributed over three pulsation periods. We have detected an asymmetric reflection nebula around the star at a distance of ≈35 mas. Three regions that change their brightness with the same characteristic time scale as the star, but with different phase shifts are identified in the nebula. We consider several hypotheses that could explain this behavior.
2 citations
TL;DR: In this article, the authors present an analysis of eleven years of Stromgren by photometry of the red semiregular variable star AI Aurigae, which shows semi-regular changes with a mean period of 65 days reaching an amplitude of 0 fraction of minute6 in some cycles.
Abstract: We present an analysis of eleven years of Stromgren by photometry of the red semiregular variable star AI Aurigae. An early period determination of 63.9 days is confirmed by the long-term light curve behaviour. The light curve shows semi-regular changes with a mean period of 65 days reaching an amplitude of 0 fraction of minute6 in some cycles. The $b-y$ colour changes perfectly parallel the V light curve, suggesting radial oscillation to be the main reason for the observed variations. We estimate the main characteristics of the star (mass, radius, effective temperature) that suggest radial pulsation in fundamental or first overtone mode.
2 citations
TL;DR: In this article, the authors present an analysis of eleven years of Stromgren by photometry of the red semiregular variable star AI Aurigae, which shows semi-regular changes with a mean period of 65 days reaching an amplitude of 0.6 mag in some cycles.
Abstract: We present an analysis of eleven years of Stromgren by photometry of the red semiregular variable star AI Aurigae. An early period determination of 63.9 days is confirmed by the long-term light curve behaviour. The light curve shows semi-regular changes with a mean period of 65 days reaching an amplitude of 0.6 mag in some cycles. The b-y colour changes perfectly parallel the V light curve, suggesting radial oscillation to be the main reason for the observed variations. We estimate the main characteristics of the star (mass, radius, effective temperature) that suggest radial pulsation in fundamental or first overtone mode.
1 citations
TL;DR: In this article, an asymmetric reflection nebula consisting of three regions and surrounding the star at the typical distance of 35 mas was detected. But the observations were conducted on 20 dates distributed over three cycles of pulsation.
Abstract: V CVn is a semiregular variable star with a V-band amplitude of $\approx2$ mag. This star has an unusually high amplitude of polarimetric variability: up to 6 per cent. It also exhibits a prominent inverse correlation between the flux and the fraction of polarization and a substantial constancy of the angle of polarization. To figure out the nature of these features, we observed the object using the Differential Speckle Polarimetry at three bands centered on 550, 625 and 880 nm using the 2.5-m telescope of Sternberg Astronomical Institute. The observations were conducted on 20 dates distributed over three cycles of pulsation. We detected an asymmetric reflection nebula consisting of three regions and surrounding the star at the typical distance of 35 mas. The components of the nebula change their brightness with the same period as the star, but with significant and different phase shifts. We discuss several hypotheses that could explain this behavior.
1 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2019 | 2 |
| 2005 | 1 |
| 2001 | 2 |
| 1993 | 1 |
| 1992 | 1 |
| 1985 | 1 |