T Tauri

[
AAVSO visual light curve of T Tau showing a typical 200-day oscillatory interval. The plot is based upon averages of all observations received within one day, and lines connecting the observations have been added as a visual aid. ] Starbox begin
name=T TauriStarbox observe
epoch=J2000
ra=04h 21m 59.4345s
dec=+19° 32' 06.429"
appmag_v=9.6
constell=Taurus Starbox character
class=G5V:e
b-v=?
u-b=?
variable=None Starbox astrometry
radial_v=24.6
prop_mo_ra=15.45
prop_mo_dec= -12.48
parallax=5.66
p_error=1.58
absmag_v=? Starbox detail
mass=?
radius=?
luminosity=?
temperature=?
metal=?
rotation=?
age=? Starbox catalog
names= V* T Tau, HBC 35, AG+19° 341, HD 284419, BD+19° 706, HH 355, HIC 20390, HIP 20390, JP11 3794, VDB 28.

T Tauri is a variable star in the constellation Taurus, the prototype of the T Tauri stars. It was discovered in October 1852 by John Russell Hind. T Tauri appears from Earth amongst the Hyades cluster, not far from ε Tauri; but it is actually 420 light years behind it and was not formed with the rest of them.

Like all T Tauri stars, it is very young, being only a million years old. Its distance from Earth is about 580 light years, and its apparent magnitude varies unpredictably from about 9.3 to 14. The T Tauri system consists of at least three stars, only one of which is visible at optical wavelengths; the other two shine in the infrared and one of them also emits radio waves. Through VLA radio observations, it was found that the young star (the "T Tauri star" itself) dramatically changed its orbit after a close encounter with one of its companions and may have been ejected from the system.

Physically nearby is NGC 1555, a reflection nebula known as Hind's Nebula or Hind's Variable Nebula. It is illuminated by T Tauri, and thus also varies in brightness. The nebula NGC 1554 was likewise associated with T Tauri and was observed in 1868 by Otto Struve, but soon disappeared or perhaps never existed, and is known as "Struve's Lost Nebula".

A Herbig-Haro object also appears to be associated with Hind's nebula, or perhaps with the T Tauri system itself.

The T Tauri wind, so named because this young star is currently in this stage, is a phase of stellar development between the accretion of material from the slowing rotating material of a solar nebula and the ignition of the Hydrogen that has agglomerated into the protostar. A protostar is the denser parts of a cloud core, typically with a mass around 10⁴ solar masses in the form of gas and dust, that collapses under its own weight/gravity, and continues to attract matter.

The protostar, at first, only has about 1% of its final mass. But the envelope of the star continues to grow as infalling material is accreted. After a few million years, thermonuclear fusion begins in its core, then a strong stellar wind is produced which stops the infall of new mass. The protostar is now considered a young star since its mass is fixed, and its future evolution is now set.

External links

* [http://www.aavso.org/vstar/vsots/0201.shtml AAVSO Variable Star of the Month Profile of T Tauri]
* http://www.kencroswell.com/TTauri.html
* http://www.spaceref.com/news/viewpr.html?pid=10340
* http://www.daviddarling.info/encyclopedia/T/T_Tauri.html
* [http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=T+Tauri&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id Simbad]