ST Cephei
 ST Cephei, as seen during the Digitized Sky Survey | |
| Object type | Variable star |
|---|---|
| Other designations | ST Ceph, HD 239978, SAO 34529, BD+56 2793 |
Observation data (Epoch J2000) | |
| Constellation | Cepheus |
| 22h 30m 10.73s | |
| Declination | +57º 00’ 03,1’’ |
| Distance | ~2,715 ly |
In visual light (V) | |
| +7,84 | |
| Temperature | 3,600 K |
ST Cephei (ST Cep)[1] is a large variable star located in the constellation Cepheus. It has a mean apparent magnitude of +7.84, and a solar radius of 1,218.
Distance
[edit]ST Cephei is very far from the solar system, whose parallax was not measured by the Hipparcos satellite. Its membership in the Cepheus OB2-B stellar association allows its distance to be estimated at 830 parsecs, or 2,715 light years.
Characteristics
[edit]ST Cephei is a red supergiant of spectral type M3I—previously cataloged as M2I—with an effective temperature of 3,600 Kelvin. It is a large supergiant, with a diameter around 290 times larger than the diameter of the Sun;[1] another study, however, reduces this figure to 175 solar radii.[2] Considering an intermediate radius between both values, if it were in the place of the Sun, its surface would extend to the Earth's orbit. Despite this, its size is far from the two known hypergiants in this constellation, Me Cephei and VV Cephei.[1][2][3]
The bolometric luminosity of ST Cephei is 8,400 times greater than that of the Sun. It has a mass 9 times greater than the Sun, at the limit from which stars end their lives by exploding as supernovae. Like other analogous supergiants, it loses mass; Its loss of stellar mass—in the form of dust, since the atomic and molecular gas could not be evaluated—is quantified at 2.5 × 10-9 solar masses per year.[2]
Listed as an LC irregular variable star, the brightness of ST Cephei varies by about two magnitudes, with no period recognized.[1]
See also
[edit]References
[edit]- ^ a b c d ST Cephei (General Catalogue of Variable Stars)
- ^ a b c "Atmospheric dynamics and the mass loss process in red supergiant stars". Astronomy and Astrophysics. 469 (2). 2007. pp. 671-680.
- ^ Levesque, Emily M.; Massey, Philip; Olsen, K. A. G.; Plez, Bertrand; Josselin, Eric; Maeder, Andre; Meynet, Georges (2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought". The Astrophysical Journal. 628 (2). pp. 973-985.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
