RV Tauri variable
Encyclopedia
RV Tauri variables are supergiant
variable stars. They exhibit changes in luminosity
which are tied to radial pulsations of their surfaces. Their changes in brightness are also correlated with changes in their spectral type
. While at their brightest, the star
s have spectral types F or G. At their dimmest, their spectral types change to K or M. The formal period of brightness fluctuations is typically around 30 to 150 days, and exhibits alternating primary and secondary minima, which can change relative to each other. Difference between maximum and minimum brightness can be as much as four magnitudes
. RV Tauri stars are further subclassified into two types:
The prototype of these variables, RV Tauri
is a RVb type variable which exhibits brightness variations between magnitudes +9.8 and +13.3 with a formal period of 78.7 days.
RV Tauri stars are post-AGB objects. They are thought to be mostly binaries with dust possibly confined to a disc.
TW Cam distance estimate may be too large.
R Sct
may be less luminous than given in the table. It may be a thermal-pulsing AGB star, observed in a helium-burning phase instead of a post-AGB star.
Supergiant
Supergiants are among the most massive stars. They occupy the top region of the Hertzsprung-Russell diagram. In the Yerkes spectral classification, supergiants are class Ia or Ib . They typically have bolometric absolute magnitudes between -5 and -12...
variable stars. They exhibit changes in luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
which are tied to radial pulsations of their surfaces. Their changes in brightness are also correlated with changes in their spectral type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
. While at their brightest, the star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s have spectral types F or G. At their dimmest, their spectral types change to K or M. The formal period of brightness fluctuations is typically around 30 to 150 days, and exhibits alternating primary and secondary minima, which can change relative to each other. Difference between maximum and minimum brightness can be as much as four magnitudes
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
. RV Tauri stars are further subclassified into two types:
- RVa variables: these are RV Tauri variables which do not vary in mean brightness
- RVb variables: these are RV Tauri variables which show periodic variations in their mean brightness, so that their maxima and minima change on 600 to 1500 day timescales
The prototype of these variables, RV Tauri
RV Tauri
RV Tauri is a star in the constellation Taurus. It is a yellow supergiant and is the prototype of a class of pulsating variables known as RV Tauri variables.RV Tau gives a better idea of the lives and deaths of stars like our Sun...
is a RVb type variable which exhibits brightness variations between magnitudes +9.8 and +13.3 with a formal period of 78.7 days.
RV Tauri stars are post-AGB objects. They are thought to be mostly binaries with dust possibly confined to a disc.
Brightest Members
There are just over 100 known RV Tauri stars. The brightest RV Tauri stars are listed below.| Star |
Brighest Magnitude Apparent magnitude The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere... |
Dimmest Magnitude |
Period (in days) |
Distance period–luminosity (in parsec Parsec The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres .... s) |
Luminosity Luminosity Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function... (Sun Sun The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields... s) |
|---|---|---|---|---|---|
| R Sct R Scuti R Scuti is a star in the constellation of Scutum. It is a yellow supergiant and is a pulsating variable known as a RV Tauri variable.It was discovered in 1795 by Edward Pigott at a time when only a few variable stars were known to exist... |
4.9 | 6.9 | 140.2 | 750 ± 290 | 9400 ± 7100 |
| U Mon | 5.1 | 7.1 | 92.26 | 770 ± 280 | 3800 ± 2700 |
| AC Her | 6.4 | 8.7 | 75.4619 | 1130 ± 390 | 2400 ± 1600 |
| V Vul | 8.1 | 9.4 | 75.72 | ||
| AR Sgr | 8.1 | 12.5 | 87.87 | ||
| SS Gem | 8.3 | 9.7 | 89.31 | ||
| R Sge | 8.5 | 10.5 | 70.594 | ||
| AI Sco | 8.5 | 11.7 | 71.0 | ||
| TX Oph | 8.8 | 11.1 | 135 | ||
| RV Tau RV Tauri RV Tauri is a star in the constellation Taurus. It is a yellow supergiant and is the prototype of a class of pulsating variables known as RV Tauri variables.RV Tau gives a better idea of the lives and deaths of stars like our Sun... |
8.8 | 12.3 | 76.698 | 2170 ± 720 | 3700 ± 2600 |
| UZ Oph | 9.2 | 11.8 | 87.44 | ||
| TW Cam | 9.4 | 10.5 | 85.6 | 3100 ± 1100 | 3700 ± 2600 |
| TT Oph | 9.4 | 11.2 | 61.08 | ||
| UY CMa | 9.8 | 11.8 | 113.9 | 8400 ± 3100 | 4500 ± 3300 |
| DF Cyg | 9.8 | 14.2 | 49.8080 | ||
| CT Ori | 9.9 | 11.2 | 135.52 | ||
| SU Gem | 9.9 | 12.2 | 50.12 | 2110 ± 660 | 1200 ± 770 |
TW Cam distance estimate may be too large.
R Sct
R Scuti
R Scuti is a star in the constellation of Scutum. It is a yellow supergiant and is a pulsating variable known as a RV Tauri variable.It was discovered in 1795 by Edward Pigott at a time when only a few variable stars were known to exist...
may be less luminous than given in the table. It may be a thermal-pulsing AGB star, observed in a helium-burning phase instead of a post-AGB star.
External links
- GCVS: List of RV variable stars
- AAVSO: Quick Look View of AAVSO Observations (get recent magnitude estimates)