RV Tauri
Encyclopedia
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 variable
s.
RV Tau gives a better idea of the lives and deaths of stars like our Sun
. It is likely a post-Asymptotic Giant Branch
(AGB) star which is in the end stages of its life, just prior to the expulsion of planetary nebula
and the eventual contraction into a white dwarf
. Evolution models of Sun-like stars show it takes about 10 billion years for a 1 solar mass star to reach the Asymptotic Giant Branch.
RV Tau was discovered to be variable in 1905 by Lydia Ceraski, and by 1907 it was clear that it had an alternating minima. Over a period of 78.5 days its brightness can vary from magnitude +9.5 to +13.5. This change in luminosity is accompanied by a change in spectral type
, being classified as G2 at its brightest and M2 at its dimmest. In addition to the fundamental period given, RV Tauri also exhibits slower variations in its mean luminosity over a period of 1100 days, during which time the maximum and minimum luminosity decreases. RV Tau is well placed for visual+CCD northern hemisphere observers during the northern winter months.
When RV Tau was assumed to have an absolute magnitude
(M) of -3.65, it was estimated to be at a distance of about 1607 pc. Since RV Tau is surrounded by a circumstellar disc, it has been estimated that RV Tau is at a distance of about 2170 pc.
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...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Taurus
Taurus (constellation)
Taurus is one of the constellations of the zodiac. Its name is a Latin word meaning 'bull', and its astrological symbol is a stylized bull's head:...
. It is a yellow supergiant
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...
and is the prototype of a class of pulsating variables known as RV Tauri variable
RV Tauri variable
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 stars have spectral types F or G. At...
s.
RV Tau gives a better idea of the lives and deaths of stars like our 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...
. It is likely a post-Asymptotic Giant Branch
Asymptotic Giant Branch
The asymptotic giant branch is the region of the Hertzsprung-Russell diagram populated by evolving low to medium-mass stars. This is a period of stellar evolution undertaken by all low to intermediate mass stars late in their lives....
(AGB) star which is in the end stages of its life, just prior to the expulsion of planetary nebula
Planetary nebula
A planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life...
and the eventual contraction into a white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
. Evolution models of Sun-like stars show it takes about 10 billion years for a 1 solar mass star to reach the Asymptotic Giant Branch.
RV Tau was discovered to be variable in 1905 by Lydia Ceraski, and by 1907 it was clear that it had an alternating minima. Over a period of 78.5 days its brightness can vary from magnitude +9.5 to +13.5. This change in luminosity is accompanied by a change in 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...
, being classified as G2 at its brightest and M2 at its dimmest. In addition to the fundamental period given, RV Tauri also exhibits slower variations in its mean luminosity over a period of 1100 days, during which time the maximum and minimum luminosity decreases. RV Tau is well placed for visual+CCD northern hemisphere observers during the northern winter months.
When RV Tau was assumed to have an absolute magnitude
Absolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
(M) of -3.65, it was estimated to be at a distance of about 1607 pc. Since RV Tau is surrounded by a circumstellar disc, it has been estimated that RV Tau is at a distance of about 2170 pc.
External links
- AAVSO: Quick Look View of AAVSO Observations (get recent magnitude estimates for RV Tau)