Gliese 445

Gliese 445 (Gl 445 or AC +79 3888) is an M-type main sequence star in the northern part of the constellation Camelopardalis.

Gliese 445

Image of AC +79 3888 (circled), also known as Gliese 445, located 17.1 light-years from Earth
Credit: Caltech/Palomar
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Camelopardalis
Right ascension 11h 47m 41.3885s[1]
Declination +78° 41′ 28.179″[1]
Apparent magnitude (V) 10.80[2]
Characteristics
Spectral type M4.0Ve[3]
B−V color index 1.572[2]
Astrometry
Radial velocity (Rv)−111.707[1] km/s
Proper motion (μ) RA: 748.111[1] mas/yr
Dec.: 480.804[1] mas/yr
Parallax (π)190.2625 ± 0.0475[1] mas
Distance17.142 ± 0.004 ly
(5.256 ± 0.001 pc)
Absolute magnitude (MV)12.227[4]
Details
Mass0.14[5] M☉
Radius0.285[4] R☉
Luminosity0.008[6] L☉
Surface gravity (log g)4.72[6] cgs
Temperature3,507[1] K
Metallicity [Fe/H]−0.30[4] dex
Rotational velocity (v sin i)<2.5[7] km/s
Other designations
Gliese 445, Gl 445, G 254-29, AC+79 3888, HIP 57544, LFT 849, LHS 2459, LTT 13235, NLTT 28539, PLX 2722[8]
Database references
SIMBADdata
ARICNSdata

Location
Distances of the nearest stars from 20,000 years ago until 80,000 years in the future

It is currently 17.1 light-years from Earth and has an apparent magnitude of 10.8. It is visible from north of the Tropic of Cancer all night long, but not to the naked eye.[9] Because the star is a red dwarf with a mass only a quarter to a third of that of our Sun, scientists question the ability of this system to support life.[9] Gliese 445 is also a known X-ray source.[10]

The Voyager 1 probe and Gliese 445 will pass one another within 1.6 light-years in about 40,000 years.[11] By that time Gliese 445 will be in a part of the sky different from its present location. The probe will no longer be operational. Also, given the star's inherent low brightness, even at that distance it would be barely visible to the naked eye of a hypothetical human being, with an apparent magnitude of only 5.72.

Solar encounter

While the Voyager probe moves through space towards a 1.6-light-year minimum distance from Gliese 445, the star is rapidly approaching our Sun. At the time the probe passes Gliese 445, the star will be about 1.059 parsecs (3.45 light-years) from our Sun,[12] but with less than half the brightness necessary to be seen with the naked eye.[9] At that time, Gliese 445 will be approximately tied with Ross 248 for being the closest star to our Sun (see List of nearest stars#Future and past).

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Urban, S. E.; Zacharias, N.; Wycoff, Observatory G. L. U. S. Naval; Washington, 2004-2006 D. C. (2004). "VizieR Online Data Catalog: The UCAC2 Bright Star Supplement (Urban+, 2006)". VizieR On-line Data Catalog. Bibcode:2004yCat.1294....0U.
  3. Lépine, Sébastien; Hilton, Eric J.; Mann, Andrew W.; Wilde, Matthew; Rojas-Ayala, Bárbara; Cruz, Kelle L.; Gaidos, Eric (2013). "A Spectroscopic Catalog of the Brightest (J < 9) M Dwarfs in the Northern Sky". The Astronomical Journal. 145 (4): 102. arXiv:1206.5991. Bibcode:2013AJ....145..102L. doi:10.1088/0004-6256/145/4/102. S2CID 117144290.
  4. Houdebine, Éric R.; Mullan, D. J.; Doyle, J. G.; de la Vieuville, Geoffroy; Butler, C. J.; Paletou, F. (2019). "The Mass-Activity Relationships in M and K Dwarfs. I. Stellar Parameters of Our Sample of M and K Dwarfs". The Astronomical Journal. 158 (2): 56. arXiv:1905.07921. Bibcode:2019AJ....158...56H. doi:10.3847/1538-3881/ab23fe. S2CID 159041104.
  5. Gaidos, E.; Mann, A. W.; Lépine, S.; Buccino, A.; James, D.; Ansdell, M.; Petrucci, R.; Mauas, P.; Hilton, E. J. (2014). "Trumpeting M dwarfs with CONCH-SHELL: A catalogue of nearby cool host-stars for habitable exoplanets and life". Monthly Notices of the Royal Astronomical Society. 443 (3): 2561. arXiv:1406.7353. Bibcode:2014MNRAS.443.2561G. doi:10.1093/mnras/stu1313. S2CID 119234492.
  6. McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. S2CID 73594365.
  7. Stelzer, B.; Marino, A.; Micela, G.; López-Santiago, J.; Liefke, C. (2013). "The UV and X-ray activity of the M dwarfs within 10 pc of the Sun". Monthly Notices of the Royal Astronomical Society. 431 (3): 2063. arXiv:1302.1061. Bibcode:2013MNRAS.431.2063S. doi:10.1093/mnras/stt225. S2CID 119193975.
  8. "GJ 445". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved July 29, 2008.
  9. Mark Littmann (1 January 2004). Planets Beyond: Discovering the Outer Solar System. Courier Corporation. ISBN 978-0-486-43602-9.
  10. Schmitt JHMM; Fleming TA; Giampapa MS (September 1995). "The X-Ray View of the Low-Mass Stars in the Solar Neighborhood". Astrophys. J. 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.
  11. "NASA – Voyager - Mission - Interstellar Mission". Jet Propulsion Laboratory. Retrieved 2020-04-03.
  12. Bobylev, Vadim V. (March 2010). "Searching for Stars Closely Encountering with the Solar System". Astronomy Letters. 36 (3): 220–226. arXiv:1003.2160. Bibcode:2010AstL...36..220B. doi:10.1134/S1063773710030060. S2CID 118374161.
  • Wikisky image of TYC 4553-192-1 (Gliese 445)
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