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Upsilon Andromedae

Coordinates: Sky map 01h 36m 47.8s, 41° 24′ 20″
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This article is about the extrasolar planet host star. For the Mira-type variable star, see U Andromedae.
Upsilon Andromedae

A conception of Upsilon Andromedae A, here showing 2 out of 4 known planets.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
Right ascension 01h 36m 47.84s[1]
Declination +41° 24′ 19.6″[1]
Apparent magnitude (V) 4.09[2]
Characteristics
Spectral type F8V[2]/M4.5V[3]
Apparent magnitude (B) 4.63[2]
U−B color index 0.06
B−V color index 0.54
V−R color index 0.30
R−I color index 0.30
Astrometry
Radial velocity (Rv)-28.9 ± 0.9[2] km/s
Proper motion (μ) RA: -173.33 ± 0.20[1] mas/yr
Dec.: -381.80 ± 0.13[1] mas/yr
Parallax (π)74.12 ± 0.19 mas[1]
Distance44.0 ± 0.1 ly
(13.49 ± 0.03 pc)
Absolute magnitude (MV)3.44
Details
Mass1.28 M☉
Radius1.480 ± 0.087[4] R☉
Luminosity3.4 L☉
Surface gravity (log g)3.83 cgs
Temperature6,074 ± 13.1[5] K
Metallicity100%
Rotation~10 days
Rotational velocity (v sin i)~8 km/s
Age3.3 × 109 years
Other designations
50 Andromedae, Gl 61, HR 458, BD +40°332, HD 9826, LTT 10561, GCTP 331.00, SAO 37362, FK5 1045, GC 1948, CCDM 01367+4125, WDS 01368+4124A, HIP 7513
Database references
SIMBADdata
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

Upsilon Andromedae (υ Andromedae, υ And) is a binary star located approximately 44 light-years away from Earth in the constellation Andromeda. The primary star (Upsilon Andromedae A) is a yellow-white dwarf star that is somewhat younger than the Sun. The second star in the system (Upsilon Andromedae B) is a red dwarf located in a wide orbit.

As of 2010, four confirmed extrasolar planets are known in orbit around the primary star. All four are likely to be jovian planets that are comparable to Jupiter. Upsilon Andromedae was both the first multiple-planet planetary system to be discovered around a main sequence star, and the first multiple-planet system known in a multiple star system. Upsilon Andromedae A was ranked 21st in the list of top 100 target stars for the NASA Terrestrial Planet Finder mission, which has, however, been reported to have been cancelled as of 2011.[6]

Distance and visibility

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 dimmer star Upsilon Andromedae B is only visible with a telescope.

System components

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.[7] 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.[8]

Upsilon Andromedae B is a red dwarf of spectral type M4.5V located at a distance (in the plane of the sky) 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 us and the Upsilon Andromedae stars is unknown, so this value is a minimum separation. It was discovered in 2002 in data collected as part of the Two Micron All Sky Survey.[3] The star is less massive and far less luminous than the Sun.

The Washington Double Star Catalog lists two optical components; however, these do not share the system's proper motion and only appear close to Upsilon Andromedae because they happen to lie near the same line of sight.[9]

Planetary system

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.[10] 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.[11]

Artist's conception of the planets of Upsilon Andromedae.

Even when this 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.[12] The two outer planets were designated Upsilon Andromedae c and Upsilon Andromedae d in order of increasing distance from the star. Both of the two outer planets are in more eccentric orbits than any of the planets in the Solar System (including Pluto).[13] The outermost planet resides in the system's habitable zone.[8]

The system is not coplanar. The mutual inclination between c and d is 35 degrees.[14] In 2001, preliminary astrometric measurements suggested the orbit of the outermost planet is inclined at 155.5° to the plane of the sky.[15] However, subsequent investigation of the data reduction techniques used suggests that the Hipparcos measurements are not precise enough to adequately characterize the orbits of substellar companions.[16] Astrometry of the innermost planet, meanwhile, constrained its inclination to 30-90 degrees. Full publication is expected in 2008.[17] The orbit of Upsilon Andromedae c gradually oscillates between circular and eccentric states every 6,700 years. 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.[18]

Some simulations show that the eccentricity of the system's planets may have arisen from a close encounter between the outer planet and a fourth planet, with the result that the fourth planet was ejected from the system or destroyed.[19] If so, the rogue planet would have had to eject immediately; it is unclear how likely this situation might be. Other models are possible.[20] However, a fourth planet (Upsilon Andromedae e) was discovered in 2010. This planet is in a 3:1 resonance with Upsilon Andromedae d.[21]

Upsilon Andromedae does not appear to have a circumstellar dust disk similar to the Kuiper belt in the Solar System.[22] This may be the result of perturbations from the companion star removing material from the outer regions of the Upsilon Andromedae A system.[3]

The Upsilon Andromedae A planetary system[23]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b 1.4[24] MJ 0.0595 ± 0.0034 4.617136 ± 0.000047 0.013 ± 0.016 — —
c 13.98[24] MJ 0.832 ± 0.048 241.33 ± 0.20 0.224 ± 0.021 — —
d 10.25[24] MJ 2.53 ± 0.15 1278.1 ± 2.9 0.267 ± 0.021 — —
e ≥1.059 ± 0.028[21] MJ 5.2456 ± 0.00067 3848.86 ± 0.74 0.00536 ± 0.00044 — —

See also

References

  1. ^ a b c d e f van Leeuwen, F. (2007). "HIP 7513". Hipparcos, the New Reduction. Retrieved 2009-12-07.
  2. ^ a b c d "SIMBAD query result: NLTT 5367 -- High proper-motion Star". Centre de Données astronomiques de Strasbourg. Retrieved 2009-05-20.
  3. ^ a b c Lowrance, P.; et al. (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. {{cite journal}}: Explicit use of et al. in: |author= (help)
  4. ^ Gerard T. van Belle and Kaspar von Braun (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars" (abstract). The Astrophysical Journal. 694 (2): 1085–1098. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085.(web Preprint)
  5. ^ Kovtyukh; Soubiran, C.; Belik, S. I.; Gorlova, N. I.; et al. (2003). "High precision effective temperatures for 181 F-K dwarfs from line-depth ratios". Astronomy and Astrophysics. 411 (3): 559–564. arXiv:astro-ph/0308429. Bibcode:2003A&A...411..559K. doi:10.1051/0004-6361:20031378. {{cite journal}}: Explicit use of et al. in: |author= (help)
  6. ^ Mullen, Leslie (02 June 2011). "Rage Against the Dying of the Light". Astrobiology Magazine. Retrieved 2011-06-07. {{cite web}}: Check date values in: |date= (help)
  7. ^ Holmberg; et al. (2007). "Record 970". Geneva-Copenhagen Survey of Solar neighbourhood. Retrieved 19 November 2008. {{cite web}}: Explicit use of et al. in: |author= (help)
  8. ^ a b Buccino, A.; et al. (2006). "Ultraviolet Radiation Constraints around the Circumstellar Habitable Zones". Icarus. 183 (2): 491–503. arXiv:astro-ph/0512291. Bibcode:2005astro.ph.12291B. doi:10.1016/j.icarus.2006.03.007. {{cite journal}}: Explicit use of et al. in: |author= (help)
  9. ^ Mason, D.; et al. "Washington Double Star Catalog - Current Version". Retrieved 5 July 2006. {{cite web}}: Explicit use of et al. in: |author= (help)
  10. ^ Butler; Marcy, Geoffrey W.; Williams, Eric; Hauser, Heather; Shirts, Phil; 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. {{cite journal}}: Explicit use of et al. in: |author= (help)
  11. ^ 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. {{cite journal}}: Explicit use of et al. in: |author= (help)
  12. ^ Butler; Marcy, Geoffrey W.; Fischer, Debra A.; Brown, Timothy M.; Contos, Adam R.; Korzennik, Sylvain G.; Nisenson, Peter; Noyes, Robert W.; 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. {{cite journal}}: Explicit use of et al. in: |author= (help)
  13. ^ Butler, R.; 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. {{cite journal}}: Explicit use of et al. in: |author= (help) (web version)
  14. ^ McArthur, B., Benedict, G. F., Bean, J., & Martioli, E. (2007). "Planet Masses in the Upsilon Andromadae system determined with the HST Fine Guidance Sensors". American Astronomical Society Meeting Abstracts. 211.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  15. ^ Han, I.; et al. (2001). "Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions". The Astrophysical Journal Letters. 548 (1): L57 – L60. Bibcode:2001ApJ...548L..57H. doi:10.1086/318927. {{cite journal}}: Explicit use of et al. in: |author= (help)
  16. ^ Pourbaix, D. and Arenou, F. (2001). "Screening the Hipparcos-based astrometric orbits of sub-stellar objects". Astronomy and Astrophysics. 372 (3): 935–944. arXiv:astro-ph/0104412. Bibcode:2001A&A...372..935P. doi:10.1051/0004-6361:20010597.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ^ Benedict, George F.; McArthur, B. E.; Bean, J. L. (2007). "The υ Andromedae Planetary System - Hubble Space Telescope Astrometry and High-precision Radial Velocities". Bulletin of the American Astronomical Society. 38: 185.{{cite journal}}: CS1 maint: multiple names: authors list (link) Announced American Astronomical Society Meeting 210, #78.02
  18. ^ 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  19. ^ Ford, E.; 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. {{cite journal}}: Explicit use of et al. in: |author= (help)
  20. ^ Rory Barnes; Richard Greenberg (2008). "Extrasolar Planet Interactions". arXiv:0801.3226v1 [astro-ph].
  21. ^ a b 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. {{cite journal}}: Explicit use of et al. in: |author= (help)
  22. ^ Trilling, D.; et al. (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. {{cite journal}}: Explicit use of et al. in: |author= (help)
  23. ^ Wright; Upadhyay, S.; Marcy, G. W.; Fischer, D. A.; Ford, Eric B.; Johnson, John Asher; et al. (2009). "Ten New and Updated Multi-planet Systems, and a Survey of Exoplanetary Systems" (abstract). The Astrophysical Journal. 693 (2): 1084–1099. Bibcode:2009ApJ...693.1084W. doi:10.1088/0004-637X/693/2/1084. {{cite journal}}: Explicit use of et al. in: |author= (help)(web Preprint)
  24. ^ a b c McArthur; et al. (2010). "New Observational Constraints on the υ Andromedae System with Data from the Hubble Space Telescope and Hobby Eberly Telescope" (PDF). {{cite journal}}: Cite journal requires |journal= (help); Explicit use of et al. in: |author= (help)
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