Mu Pegasi
 Location of μ Pegasi (circled) |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Pegasus |
| Right ascension | 22h 50m 00.19315s[1] |
| Declination | +24° 36′ 05.6984″[1] |
| Apparent magnitude (V) | 3.514[2] |
| Characteristics | |
| Spectral type | G8 III[3] |
| U−B color index | +0.674[2] |
| B−V color index | +0.932[2] |
| Astrometry | |
| Radial velocity (Rv) | +13.54 ± 0.20[4] km/s |
| Proper motion (μ) | RA: +144.70[1] mas/yr Dec.: –41.87[1] mas/yr |
| Parallax (π) | 30.74 ± 0.27[1] mas |
| Distance | 106.1 ± 0.9 ly (32.5 ± 0.3 pc) |
| Details | |
| Mass | 1.3[5] M☉ |
| Radius | 9.6 ± 0.4[6] R☉ |
| Surface gravity (log g) | 2.50[3] |
| Temperature | 4,950[3] K |
| Metallicity [Fe/H] | –0.03[3] dex |
| Rotational velocity (v sin i) | 4.0[7] km/s |
| Other designations | |
Mu Pegasi (μ Peg, μ Pegasi) is a star in the northern constellation of Pegasus. It has the traditional name Sadalbari, which derives from the arabic term for "luck star of the splendid one"—a name it shares with the neighboring star Lambda Pegasi.[9] The apparent visual magnitude of this star is 3.5,[2] which is bright enough to be seen with the naked eye even on a moonlit night. The distance to this star can be determined with parallax measurements, which yields a value of 106.1 light-years (32.5 parsecs).[1]
The spectrum of this star matches a stellar classification of G8 III.[3] The luminosity class of 'III' means that it has exhausted the hydrogen fuel at its core and evolved into a giant star. It is slightly more massive than the Sun, but has expanded to nearly ten times the Sun's radius.[6] The effective temperature of the outer atmosphere is about 4,950 K,[3] which is cooler than the Sun and gives it the yellow hue of a G-type star.[10] The abundance of elements other than hydrogen and helium, what astronomers term the metallicity, is similar to the abundance in the Sun.[3]
[edit] References
- ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, Bibcode 2007A&A...474..653V, doi:10.1051/0004-6361:20078357
- ^ a b c d Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants.", Monthly Notices of the Royal Astronomical Society 172: 667–679, Bibcode 1975MNRAS.172..667J
- ^ a b c d e f g Frasca, A. et al. (December 2009), "REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters", Astronomy and Astrophysics 508 (3): 1313–1330, Bibcode 2009A&A...508.1313F, doi:10.1051/0004-6361/200913327
- ^ Famaey, B. et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode 2005A&A...430..165F, doi:10.1051/0004-6361:20041272
- ^ Smith, G. (November 1998), "Stellar atmospheric parameters for the giant stars MU Pegasi and lambda Pegasi", Astronomy and Astrophysics 339: 531-536, Bibcode 1998A&A...339..531S
- ^ a b Nordgren, Tyler E. et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal 118 (6): 3032-3038, Bibcode 1999AJ....118.3032N, doi:10.1086/301114
- ^ Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, Bibcode 2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
- ^ "48 Peg -- High proper-motion Star", SIMBAD (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+216131, retrieved 2012-01-28
- ^ Kaler, James B., "SADALBARI (Lambda and Mu Pegasi)", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/sadalbari.html, retrieved 2012-01-28
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16
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