Ross 248
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 41m 54.99s[1] |
| Declination | +44° 10′ 40.8″[1] |
| Apparent magnitude (V) | 12.29[2] |
| Characteristics | |
| Spectral type | M6e[3] |
| U−B color index | +1.48[2] |
| B−V color index | +1.92[2] |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | -81[4] km/s |
| Proper motion (μ) | RA: 111[5] mas/yr Dec.: -1584[5] mas/yr |
| Parallax (π) | 316.80 ± 1.10[6] mas |
| Distance | 10.3 ± 0.04 ly (3.16 ± 0.01 pc) |
| Absolute magnitude (MV) | 14.79[7] |
| Details | |
| Mass | 0.12[8] M☉ |
| Radius | 0.16[9] R☉ |
| Surface gravity (log g) | 5.12[3] |
| Luminosity | 0.0018[10] L☉ |
| Temperature | 2,799[3] K |
| Rotation | v sin i < 3 km/s[11] |
| Other designations | |
Ross 248 (HH Andromedae) is a red dwarf star located approximately 10.3 light years (3.2 pc) from Earth in the constellation Andromeda. This star was first catalogued by Frank Elmore Ross in 1926 with his second list of proper motion stars.[12]
This star has about 12% of the Sun's mass and 16% of the Sun's radius, but only 0.2% of the Sun's luminosity. Despite its proximity to the Earth, it is too dim to be seen with the naked eye.[13] This is a flare star that occasionally increases in luminosity.[14] With high probability there also appears to be a long-term variability with a period of 4.2 years. This variability ranged in visual magnitude from 12.23 to 12.34.[15] In 1950, this became the first star to have a small variation in magnitude attributed to spots on the photosphere.[16]
Long term observations of this star by the Sproul Observatory show no astrometric perturbations by an unseen companion.[16] The proper motion of this star was examined for a brown dwarf or stellar companion orbiting at a wide separation (between 100–1400 AU) but none was found.[17] A search for a faint companion using the Hubble Space Telescope Wide Field Planetary Camera revealed nothing,[7] nor did a search with near infrared speckle interferometry.[18] However, none of these searches rule out a companion that is smaller than the detection minima.
The space velocity components of this star are U = –32.9 ± 0.7, V = –74.3 ± 1.3 and W = 0.0 ± 1.4 km/s.[6] The trajectory of Ross 248 will bring it closer to the Solar System in the future. In 1993 Matthews suggested that in about 33,000 years Ross 248 would be the closest star to the Sun, approaching within a minimum distance of 3.024 light-years (0.927 parsecs) in 36,000 years.[19] However, it will recede thereafter and will again be further from the Sun than Proxima Centauri 42,000 years from now.[19]
The spacecraft Voyager 2 is traveling on a path headed roughly in the direction of Ross 248, and is expected to come within 1.76 light-years (0.54 parsecs) of the star in 40,176 years.[20] A spacecraft that escaped the Solar System with a velocity of 25.4 km/s would reach this star 37,000 years from now when the star is just past its nearest approach. By comparison, the Voyager 1 has an escape velocity of 16.6 km/s.[21]
[edit] See also
[edit] References
- ^ a b Cutri, R. M. et al (June 2003). 2MASS All Sky Catalog of point sources. NASA/IPAC. Bibcode 2003tmc..book.....C.
- ^ a b c d "V* HH And – Flare Star". SIMBADa. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V*+HH+And. Retrieved 2009-09-06.
- ^ a b c Cenarro, A. J.; Peletier, R. F.; Sánchez–blázquez, P.; Selam, S. O.; Toloba, E.; Cardiel, N.; Falcón–barroso, J.; Gorgas, J. et al. (2007). "Medium-resolution Isaac Newton Telescope Library of Empirical Spectra – II. The Stellar Atmospheric Parameters". Monthly Notices of the Royal Astronomical Society 374 (2): 664–690. arXiv:astro-ph/0611618. Bibcode 2007MNRAS.374..664C. doi:10.1111/j.1365-2966.2006.11196.x.
- ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode 1953QB901.W495......
- ^ a b Lépine, Sébastien; Shara, Michael M (March 2005). "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)". The Astronomical Journal 129 (3): 1483–1522. arXiv:astro-ph/0412070. Bibcode 2005AJ....129.1483L. doi:10.1086/427854.
- ^ a b Leggett, S. K. (September 1992). "Infrared colors of low-mass stars". Astrophysical Journal Supplement Series 82 (1): 351–394. Bibcode 1992ApJS...82..351L. doi:10.1086/191720.
- ^ a b Schroeder, Daniel J.; Golimowski, David A.; Brukardt, Ryan A.; Burrows, Christopher J.; Caldwell, John J.; Fastie, William G.; Ford, Holland C.; Hesman, Brigette et al. (2000). "A Search for Faint Companions to Nearby Stars Using the Wide Field Planetary Camera 2". The Astronomical Journal 119: 906–922. Bibcode 2000AJ....119..906S. doi:10.1086/301227.
- ^ "The One Hundred Nearest Star Systems". Research Consortium on Nearby Stars. 2009-01-01. http://www.chara.gsu.edu/RECONS/TOP100.posted.htm. Retrieved 2009-09-06.
- ^ Johnson, H. M.; Wright, C. D. (November 1983). "Predicted infrared brightness of stars within 25 parsecs of the Sun". Astrophysical Journal Supplement Series 53: 643–711. Bibcode 1983ApJS...53..643J. doi:10.1086/190905. See p. 705.
- ^ West, Frederick R. (June 1999). "Monitoring Nearby Stars for Transits by Extrasolar Jovial Planets, II: Transits of M-Type (Red) Dwarf Stars by Close Extrasolar Giant (Jovian) Planets". The Journal of the American Association of Variable Star Observers 27 (1): 77–78. Bibcode 1999JAVSO..27...77W.
- ^ Reiners, A.; Basri, G. (February 2007). "The First Direct Measurements of Surface Magnetic Fields on Very Low Mass Stars". The Astrophysical Journal 656 (2): 1121–1135. arXiv:astro-ph/0610365. Bibcode 2007ApJ...656.1121R. doi:10.1086/510304.
- ^ Ross, Frank E. (February 1926). "New proper-motion stars, (second list)". Astronomical Journal 36 (856): 124–128. Bibcode 1926AJ.....36..124R. doi:10.1086/104699.
- ^ Routray, Sudhir K. (2004), Light Years Away: The Whole Creation at a Glance, iUniverse, p. 31, ISBN 0595335829, http://books.google.com/books?id=BES00I8VayEC&pg=PA31
- ^ Poveda, Arcadio; Allen, Christine; Herrera, Miguel Angel (1996). "Chromospheric Activity, Stellar Winds and Red Stragglers". Workshop on Colliding Winds in Binary Stars to Honor Jorge Sahade. 5. Universidad Nacional Autonoma de Mexico. pp. 16–20.
- ^ Weis, Edward W. (March 1994). "Long term variability in dwarf M stars". Astronomical Journal 107 (3): 1135–1140. Bibcode 1994AJ....107.1135W. doi:10.1086/116925.
- ^ a b Lippincott, S. L. (July 1978). "Astrometric search for unseen stellar and sub-stellar companions to nearby stars and the possibility of their detection". Space Science Reviews 22: 153–189. Bibcode 1978SSRv...22..153L. doi:10.1007/BF00212072.
- ^ Hinz, Joannah L. et al (February 2002). "A Near-Infrared, Wide-Field, Proper-Motion Search for Brown Dwarfs". The Astronomical Journal 123 (4): 2027–2032. arXiv:astro-ph/0201140. Bibcode 2002AJ....123.2027H. doi:10.1086/339555.
- ^ Leinert, C.; Henry, T.; Glindemann, A.; McCarthy, D. W., Jr. (September 1997). "A search for companions to nearby southern M dwarfs with near-infrared speckle interferometry". Astronomy and Astrophysics 325: 159–166. Bibcode 1997A&A...325..159L.
- ^ a b Matthews, R. A. J. (Spring 1994). The Close Approach of Stars in the Solar Neighborhood. 35. pp. 1. Bibcode 1994QJRAS..35....1M.
- ^ Littmann, Mark (2004). Planets Beyond: Discovering the Outer Solar System. Courier Dover Publications. p. 167. ISBN 0486436020.
- ^ West, F. R. (March 1985), "A Suggested Future Space Mission to the Low-Luminosity Star Ross 248=Gliese 905", Bulletin of the American Astronomical Society 17: 552, Bibcode 1985BAAS...17..552W
[edit] Field star
| NAME | Right ascension | Declination | Apparent magnitude (V) | Spectral type | Database references |
|---|---|---|---|---|---|
| PLX 5735 | 23h 41m 54s | +44° 14' 00 | 12.6 | A5 | Simbad |
[edit] External links
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