Upsilon Andromedae

Upsilon Andromedae (υ Andromedae, abbreviated Upsilon And, υ And) is a binary star located approximately 44 light-years from Earth in the constellation of Andromeda. The system consists of an F-type main-sequence star (designated υ Andromedae A, officially named Titawin /tɪtəˈwiːn/) and a smaller red dwarf.

Not to be confused with the variable star U Andromedae.
υ Andromedae
Location of υ Andromedae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
Right ascension  01h 36m 47.84216s[1]
Declination +41° 24′ 19.6443″[1]
Apparent magnitude (V) 4.10[2]
Characteristics
Spectral type F9V[3] + M4.5V[4]
Apparent magnitude (B) 4.63[5]
U−B color index 0.06
B−V color index 0.54
V−R color index 0.30[6]
R−I color index 0.30[6]
Astrometry
υ And A
Radial velocity (Rv)−28.59±0.08[7] km/s
Proper motion (μ) RA: −172.248±0.522[8] mas/yr
Dec.: −382.898±0.543[8] mas/yr
Parallax (π)74.5711 ± 0.3491[8] mas
Distance43.7 ± 0.2 ly
(13.41 ± 0.06 pc)
Absolute magnitude (MV)3.44±0.02[9]
υ And D[lower-alpha 1]
Proper motion (μ) RA: −172.077±0.132[10] mas/yr
Dec.: −383.899±0.142[10] mas/yr
Parallax (π)74.2070 ± 0.0880[10] mas
Distance43.95 ± 0.05 ly
(13.48 ± 0.02 pc)
Details
υ And A
Mass1.27±0.06[9] M☉
Radius1.480±0.087[2] R☉
Luminosity3.57[11] L☉
Surface gravity (log g)4.0±0.1[9] cgs
Temperature6213±44[12] K
Metallicity [Fe/H]0.09±0.06[9] dex
Rotation7.3±0.04 d[13]
Rotational velocity (v sin i)9.5±0.8[9] km/s
Age3.12 ± 0.2[6] Gyr
υ And D[lower-alpha 1]
Mass0.2[4] M☉
Other designations
Titawin,[14] 50 Andromedae, BD+40 332, CCDM 01367+4125, FK5 1045, GC 1948, GCTP 331.00, Gl 61, HD 9826, HIP 7513, HR 458, LTT 10561, SAO 37362, WDS 01368+4124A
Database references
SIMBADdata
υ And D[lower-alpha 1]
Extrasolar Planets
Encyclopaedia		data
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

As of 2010, four extrasolar planets (designated Upsilon Andromedae b, c, d and e; the first three named Saffar, Samh and Majriti, respectively) are believed to orbit υ Andromedae A. All four are likely to be jovian planets that are comparable in size to Jupiter. This was both the first multiple-planet system to be discovered around a main-sequence star, and the first multiple-planet system known in a multiple star system.

Nomenclature

υ Andromedae (Latinised to Upsilon Andromedae) is the system's Bayer designation. Under the rules for naming objects in binary star systems, the two components are designated A and B.[15] Under the same rules, the first planet discovered orbiting υ Andromedae A should be designated υ Andromedae Ab. Though this more formal form is occasionally used to avoid confusion with a secondary star υ Andromedae B, it is more commonly referred to as υ Andromedae b. The other planets discovered were designated υ Andromedae c, d, and e, in order of their discovery.

In July 2014 the International Astronomical Union (IAU) launched a process for giving proper names to certain exoplanets and their host stars.[16] The process involved public nomination and voting for the new names.[17] In December 2015, the IAU announced the winning names were Titawin for υ Andromedae A and Saffar, Samh and Majriti for three of its planets (b, c, and d, respectively).[18]

The winning names were those submitted by the Vega Astronomy Club of Morocco. The star is named after the Berber form of the name of Tétouan in northern Morocco, ⵜⵉⵟⵟⴰⵡⵉⵏ tiṭṭawin, the medina (old town) of which is a UNESCO World Heritage Site. The planets honour the 10th and 11th Century astronomers Ibn al-Saffar, Ibn al-Samh and Maslama al-Majriti of Muslim Spain.[19]

In 2016, the IAU organized a Working Group on Star Names (WGSN)[20] to catalog and standardize proper names for stars. In its first bulletin of July 2016,[21] the WGSN explicitly recognized the names of exoplanets and their host stars approved by the Executive Committee Working Group Public Naming of Planets and Planetary Satellites, including the names of stars adopted during the 2015 NameExoWorlds campaign. This star is now so entered in the IAU Catalog of Star Names.[14]

In Chinese, 天大將軍 (Tiān Dà Jiāng Jūn), meaning Heaven's Great General, refers to an asterism consisting of Upsilon Andromedae, Gamma Andromedae, Phi Persei, 51 Andromedae, 49 Andromedae, Chi Andromedae, Tau Andromedae, 56 Andromedae, Beta Trianguli, Gamma Trianguli and Delta Trianguli. Consequently, the Chinese name for Upsilon Andromedae itself is 天大將軍六 (Tiān Dà Jiāng Jūn liù, English: the Sixth Star of Heaven's Great General.).[22]

Stellar system

Upsilon Andromedae is located fairly close to the Solar System: the parallax of Upsilon Andromedae A was measured by the Hipparcos astrometry satellite as 74.12 milliarcseconds, corresponding to a distance of 13.49 parsecs (44 light years).[1] Upsilon Andromedae A has an apparent magnitude of +4.09, making it visible to the naked eye even under moderately light-polluted skies, about 10 degrees east of the Andromeda Galaxy.

The Catalog of Components of Double and Multiple Stars and Washington Double Star Catalog (WDS) both list two companion stars: magnitude 12.6 UCAC3 263-13722 110" away, listed as component B; and magnitude 10.3 F2 star TYC 2822-2067-1 280" away, listed as component C.[23]

A fainter and closer star discovered in 2002, is confusingly referred to in the discovery paper as υ Andromedae B even though that designation is also used for a different companion. This 13th magnitude red dwarf is 55" from υ Andromedae A and is believed to be the only one of the companions physically associated, at the same distance and a projected separation of 750 AU. It has been added to the WDS as component D.[23]

Upsilon Andromedae A

Upsilon Andromedae A is a yellow-white dwarf of spectral type F8V, similar to the Sun, but younger, more massive, and more luminous. According to its entry in the Geneva–Copenhagen survey, the star is around 3.1 billion years old and has a similar proportion of iron relative to hydrogen to the Sun.[24] At around 1.3 solar masses, it will have a shorter lifetime than the Sun. The amount of ultraviolet radiation received by any planets in the star's habitable zone would be similar to the ultraviolet flux the Earth receives from the Sun.[25]

The X-ray emission of Upsilon Andromedae A is low for a star of its spectral class. This means that the star may be moving, or move soon, out of the main sequence and expand its radius to become a red giant star. This is consistent with the upper limits on the age of this star.[26]

Upsilon Andromedae A was ranked 21st in the list of top 100 target stars for NASA's cancelled Terrestrial Planet Finder mission.[27]

Red dwarf

The red dwarf companion has a spectral type M4.5V and is located at a projected separation of 750 AU from the primary star. The true separation between the two stars is unknown because the displacement along the line of sight between Earth and the Upsilon Andromedae stars is unknown, so this value is a minimum separation. Based upon its motion through space, this is a common proper motion companion to the primary. It was discovered in 2002 in data collected as part of the Two Micron All Sky Survey.[4] The star is less massive and far less luminous than the Sun, and its age seems to be consistent with that of the system.[26]

Planetary system
The Upsilon Andromedae A planetary system[28]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b (Saffar) 1.70+0.33
−0.24[29] MJ		 0.0594±0.0003[6] 4.62±0.23 0.022±0.007 24±4[29]° ~1.3[30] RJ
c (Samh) 13.98+2.3
−5.3[6] MJ		 0.829±0.043[6] 241.26±0.64 0.260±0.079 7.9 ± 1[6]° —
d (Majriti) 10.25+0.7
−3.3[6] MJ		 2.530±0.014[6] 1276.46±0.57 0.299±0.072 23.8 ± 1[6]° —
e > 1.059 [31] MJ ~5.25[31] 3848.86±0.74 0.0055±0.0004 — —

The star rotates at an inclination of 58+9
−7 degrees relative to Earth.[13]

The innermost planet of the Upsilon Andromedae system was discovered in 1996 and announced in January 1997, together with the planet of Tau Boötis and the innermost planet of 55 Cancri.[32] The discovery was made by Geoffrey Marcy and R. Paul Butler, both astronomers at San Francisco State University. The planet, designated Upsilon Andromedae b, was discovered by measuring changes in the star's radial velocity induced by the planet's gravity. Because of its closeness to the parent star, it induced a large wobble which was detected relatively easily. The planet appears to be responsible for enhanced activity in the chromosphere of its star.[33]

Artist's conception of the planets of Upsilon Andromedae.

Even when the first planet was taken into account, there still remained significant residuals in the radial velocity measurements, and it was suggested there might be a second planet in orbit. In 1999, astronomers at both San Francisco State University and the Harvard-Smithsonian Center for Astrophysics independently concluded that a three-planet model best fit the data.[34] The two outer planets were designated Upsilon Andromedae c and Upsilon Andromedae d in order of increasing distance from the star. Both of these planets are in more eccentric orbits than any of the planets in the Solar System (including Pluto).[35] Upsilon Andromedae d resides in the system's habitable zone.[25]

The orbital parameters of this three planet system have been fully determined. The system is not coplanar, with each other or with the stellar rotation, as in our solar system.[6] Simulations shows that the measured configuration of the planets produces indeed stable orbits for at least 100 million years, where planets b and d remain roughly coplanar. General relativity is expected to have strong effects on planet b, because it orbits at a distance of just ~0.05 AU from the parent star. The apsides of planet c and d, instead, oscillates with time;[29] the orbit of Upsilon Andromedae c thus returns to a nearly circular state every 9,000 years. The eccentricity of those planets may have arisen from a close encounter between the outer planet and a fourth planet, with the result that the third planet was ejected from the system or destroyed.[36] Such a mechanism could have been triggered by perturbations on the orbit of the companion star, which arise from close encounters with other stars and from the tidal field of the Milky Way.[37] The orbits of the two inner planets seems to be shaped by tidal interactions, while the evolution of c and d orbits is secular.[38]

The existence of further planets too small or distant to detect has not been ruled out, though the presence of Jupiter-mass planets as close as 5 AU from Upsilon Andromedae A would make the system unstable.[39] However, a fourth planet (Upsilon Andromedae e) was discovered in 2010. This planet seems to be in a 3:1 resonance with Upsilon Andromedae d;[31] other authors, while confirming evidence for a fourth planet, challenge the values found, since they use a data set inconsistent with the others.[30]

Upsilon Andromedae does not appear to have a circumstellar dust disk similar to the Kuiper belt in the Solar System.[40] This may be the result of perturbations from the companion star removing material from the outer regions of the Upsilon Andromedae A system.[4]

See also

Notes
  1. The M4.5 red dwarf has the formal designation υ And D, lettered in order of discovery, in the multiple star catalogues, but is referred to as υ And B in its discovery paper.

References
  1. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. van Belle, Gerard T.; von Braun, Kaspar (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars". The Astrophysical Journal. 694 (2): 1085–1098. arXiv:0901.1206. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085.
  3. Abt, Helmut A. (2009). "MK Classifications of Spectroscopic Binaries". The Astrophysical Journal Supplement Series. 180 (1): 117–118. Bibcode:2009ApJS..180..117A. doi:10.1088/0067-0049/180/1/117.
  4. Lowrance, Patrick J.; Kirkpatrick, J. Davy; Beichman, Charles A. (2002). "A Distant Stellar Companion in the υ Andromedae System". The Astrophysical Journal Letters. 572 (1): L79–L81. arXiv:astro-ph/0205277. Bibcode:2002ApJ...572L..79L. doi:10.1086/341554.
  5. "NLTT 5367 -- High proper-motion Star". SIMBAD Astronomical Object Database. Centre de Données astronomiques de Strasbourg. Retrieved 2009-05-20.
  6. McArthur, Barbara E.; et al. (2010). "New Observational Constraints on the υ Andromedae System with Data from the Hubble Space Telescope and Hobby Eberly Telescope" (PDF). The Astrophysical Journal. 715 (2): 1203. Bibcode:2010ApJ...715.1203M. doi:10.1088/0004-637X/715/2/1203.
  7. Nidever, David L.; Marcy, Geoffrey W.; Butler, R. Paul; Fischer, Debra A.; Vogt, Steven S. (2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series. 141 (2): 503. arXiv:astro-ph/0112477. Bibcode:2002ApJS..141..503N. doi:10.1086/340570.
  8. 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.
  9. Fuhrmann, Klaus; Pfeiffer, Michael J.; Bernkopf, Jan (August 1998), "F- and G-type stars with planetary companions: upsilon Andromedae, rho (1) Cancri, tau Bootis, 16 Cygni and rho Coronae Borealis", Astronomy and Astrophysics, 336: 942–952, Bibcode:1998A&A...336..942F.
  10. 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.
  11. Takeda, Yoichi (April 2007), "Fundamental Parameters and Elemental Abundances of 160 F-G-K Stars Based on OAO Spectrum Database", Publications of the Astronomical Society of Japan, 59 (2): 335–356, Bibcode:2007PASJ...59..335T, doi:10.1093/pasj/59.2.335.
  12. "Exoplanets Data Explorer". exoplanet.org. Retrieved 4 September 2016.
  13. Simpson, E. K.; et al. (November 2010), "Rotation periods of exoplanet host stars", Monthly Notices of the Royal Astronomical Society, 408 (3): 1666–1679, arXiv:1006.4121, Bibcode:2010MNRAS.408.1666S, doi:10.1111/j.1365-2966.2010.17230.x., as "HD 9826".
  14. "IAU Catalog of Star Names". Retrieved 28 July 2016.
  15. Hartkopf, William I.; Mason, Brian D. "Addressing confusion in double star nomenclature: The Washington Multiplicity Catalog". U.S. Naval Observatory. Retrieved 2016-01-19.
  16. NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
  17. NameExoWorlds The Process
  18. Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
  19. NameExoWorlds The Approved Names
  20. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  21. "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  22. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日
  23. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I. "Washington Double Star Catalog". United States Naval Observatory. Retrieved 2012-06-25.
  24. Holmberg; et al. (2007). "Record 970". Geneva-Copenhagen Survey of Solar neighbourhood. Retrieved 19 November 2008.
  25. Buccino, Andrea P.; et al. (2006). "Ultraviolet Radiation Constraints around the Circumstellar Habitable Zones". Icarus. 183 (2): 491–503. arXiv:astro-ph/0512291. Bibcode:2006Icar..183..491B. CiteSeerX 10.1.1.337.8642. doi:10.1016/j.icarus.2006.03.007.
  26. Poppenhaeger, K.; Wolk, S.J. (May 2014). "Indications for an influence of hot Jupiters on the rotation and activity of their host stars". Astronomy & Astrophysics. 565: L1. arXiv:1404.1073. Bibcode:2014A&A...565L...1P. doi:10.1051/0004-6361/201423454.
  27. Mullen, Leslie (2 June 2011). "Rage Against the Dying of the Light". Astrobiology Magazine. Retrieved 2011-06-07.
  28. Ligi, R.; et al. (2012). "A new interferometric study of four exoplanet host stars : θ Cygni, 14 Andromedae, υ Andromedae and 42 Draconis". Astronomy & Astrophysics. 545: A5. arXiv:1208.3895. Bibcode:2012A&A...545A...5L. doi:10.1051/0004-6361/201219467.
  29. Pizkorz, D.; et al. (August 2017). "Detection of Water Vapor in the Thermal Spectrum of the Non-transiting Hot Jupiter Upsilon Andromedae b". The Astronomical Journal. 154 (2): 78. arXiv:1707.01534. Bibcode:2017AJ....154...78P. doi:10.3847/1538-3881/aa7dd8.
  30. Deitrick, R.; et al. (January 2015). "The Three-dimensional Architecture of the υ Andromedae Planetary System". The Astrophysical Journal. 798 (1): 46. arXiv:1411.1059. Bibcode:2015ApJ...798...46D. doi:10.1088/0004-637X/798/1/46.
  31. Curiel, S.; et al. (2011). "A fourth planet orbiting υ Andromedae". Astronomy & Astrophysics. 525: A78. Bibcode:2011A&A...525A..78C. doi:10.1051/0004-6361/201015693.
  32. Butler, R. Paul; et al. (1997). "Three New 51 Pegasi-Type Planets". The Astrophysical Journal Letters. 474 (2): L115–L118. Bibcode:1997ApJ...474L.115B. doi:10.1086/310444.
  33. Shkolnik, E.; et al. (2005). "Hot Jupiters and Hot Spots: The Short- and Long-term Chromospheric Activity on Stars with Giant Planets". The Astrophysical Journal. 622 (2): 1075–1090. arXiv:astro-ph/0411655. Bibcode:2005ApJ...622.1075S. doi:10.1086/428037.
  34. Butler, R. Paul; et al. (1999). "Evidence for Multiple Companions to υ Andromedae". The Astrophysical Journal. 526 (2): 916–927. Bibcode:1999ApJ...526..916B. doi:10.1086/308035.
  35. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. (web version)
  36. Ford, Eric B.; et al. (2005). "Planet-planet scattering in the upsilon Andromedae system". Nature. 434 (7035): 873–876. arXiv:astro-ph/0502441. Bibcode:2005Natur.434..873F. doi:10.1038/nature03427. PMID 15829958.
  37. Kaib, N.A.; Raymond, S.N.; Duncan, M. (January 2013). "Planetary system disruption by Galactic perturbations to wide binary stars". Nature. 493 (7432): 381–384. Bibcode:2013Natur.493..381K. CiteSeerX 10.1.1.765.6816. doi:10.1038/nature11780. PMID 23292514.
  38. Rory Barnes; Richard Greenberg (2008). "Extrasolar Planet Interactions". Proceedings of the International Astronomical Union. 3: 469–478. arXiv:0801.3226v1. doi:10.1017/S1743921308016980.
  39. Lissauer, J.; Rivera, E. (2001). "Stability analysis of the planetary system orbiting υ Andromedae. II. Simulations using new Lick observatory fits". The Astrophysical Journal. 554 (2): 1141–1150. Bibcode:2001ApJ...554.1141L. doi:10.1086/321426.
  40. Trilling, D. E.; Brown, R. H.; Rivkin, A. S. (2000). "Circumstellar dust disks around stars with known planetary companions". The Astrophysical Journal. 529 (1): 499–505. Bibcode:2000ApJ...529..499T. doi:10.1086/308280.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.