51 Eridani

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51 Eridani
51 Eridani b orbit animated (2014-2018).gif
51 Eridani and its planet 51 Eridani b
Observation data
Epoch J2000       Equinox J2000
Constellation Eridanus
Right ascension 04h 37m 36.13234s [1]
Declination −02° 28′ 24.7749″ [1]
Apparent magnitude  (V)5.22 [2]
Characteristics
Spectral type F0 V [2]
Variable type γ Dor [3]
Astrometry
Radial velocity (Rv)12.60±0.3 [4]  km/s
Proper motion (μ)RA: 44.22 ± 0.34 [1]   mas/yr
Dec.: –64.39 ± 0.27 [1]   mas/yr
Parallax (π)33.98 ± 0.34  mas [1]
Distance 96.0 ± 1.0  ly
(29.4 ± 0.3  pc)
Absolute magnitude  (MV)2.87 [5]
Details [6]
51 Eri A
Mass 1.75±0.05 [2]   M☉
Radius 1.45±0.02  R☉
Luminosity 6.7 [7]   L☉
Surface gravity (log g)3.95±0.04  cgs
Temperature 7,331±30  K
Metallicity [Fe/H]−0.12±0.06  dex
Rotational velocity (v sin i)77.9 [8]  km/s
Other designations
c Eridani, 51 Eridani, BD−02° 963, HD  29391, HIP  21547, HR  1474, SAO  131358, 2MASS J04373613-0228248
Database references
SIMBAD data

51 Eridani is a star in the constellation Eridanus. It has an apparent magnitude of 5.22, [2] meaning it is just visible to the unaided eye in suburban and rural skies. [9] The primary star's absolute magnitude is 2.87. [5] There is also a binary star named GJ 3305 which shares the same proper motion through space with it, [10] making it overall a triple star system.

Contents

General information

Johann Bayer gave the star its Bayer designation of c Eridani, [11] using lowercase letters once he had exhausted all the letters of the Greek alphabet, in his 1603 star chart Uranometria . [12] It was catalogued as 51 Eridani by John Flamsteed in 1725. [13]

Located around 97 light-years distant, it shines with a luminosity approximately 5.38 times that of the Sun and has a surface temperature of 7,199  K . [14] A cold debris disk has been detected with a likely inner border of 82 astronomical units (AU). [15] A yellow-white main-sequence star of spectral type F0V, 51 Eridani is a member of the Beta Pictoris moving group and hence thought to be around 23 million years old. [5] Somewhat more luminous than it should be for its surface temperature, 51 Eridani has also been classified as spectral type F0IV—a type corresponding to ageing stars that have used up their core hydrogen fuel and become subgiants; however, in this case it is a phenomenon of very young stars 5 to 30 million years old that have yet to settle on the main sequence. [16]

Photometric measurements with the TESS space telescope show that this is a Gamma Doradus-like pulsating star. Nine pulsation frequencies have been detected. [3]

GJ 3305

51 Eridani has a companion, known as GJ 3305. The system has a common proper motion with 51 Eridani, and hence it is gravitationally bound, although it is separated by 66″ corresponding to 2,000 AU. It is a binary star system with two M-type red dwarfs. The primary has a mass of 0.67 ± 0.05 M☉ while the secondary has a mass of 0.44 ± 0.05 M☉. The two red dwarfs themselves are separated by a semimajor axis of 9.78 ± 0.14 AU and have an eccentricity of 0.19 ± 0.02. [10]

The star is significant as the host sun to one of the first planets to have been directly imaged in wide-orbit, and the first detected by the Gemini Planet Imager. [17]

Planetary system

51 Eridani b is a young Jupiter-like planet and was photographed, in near-infrared light, on 21 December 2014. [18] The study, led by Bruce Macintosh, a professor of physics at Stanford University and confirmed by Christian Marois found that methane and water were abundant in the atmosphere of the planet and its diameter was only slightly larger than Jupiter's. [17] It is the smallest exoplanet directly imaged to date. [19] The planetary orbit was found to be significantly eccentric by 2019. [20]

Gaia astrometry also suggests an additional planet on orbit smaller than 51 Eridani b. [20]

The planetary system [20]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(years)		 Eccentricity Inclination Radius
51 Eridani b 2.6±0.3  MJ 11.1+4.2
−1.3		28.1+17.2
−4.9		0.53+0.09
−0.13		136+10
−11 ° 		1.11+0.16
−0.13  RJ

Related Research Articles

<span class="mw-page-title-main">Epsilon Eridani</span> Star in the constellation Eridanus

Epsilon Eridani, proper name Ran, is a star in the southern constellation of Eridanus. At a declination of −9.46°, it is visible from most of Earth's surface. Located at a distance 10.5 light-years from the Sun, it has an apparent magnitude of 3.73, making it the third-closest individual star visible to the naked eye.

<span class="mw-page-title-main">Beta Pictoris</span> Second brightest star in the southern constellation of Pictor

Beta Pictoris is the second brightest star in the constellation Pictor. It is located 63.4 light-years (19.4 pc) from the Solar System, and is 1.75 times as massive and 8.7 times as luminous as the Sun. The Beta Pictoris system is very young, only 20 to 26 million years old, although it is already in the main sequence stage of its evolution. Beta Pictoris is the title member of the Beta Pictoris moving group, an association of young stars which share the same motion through space and have the same age.

Eta Telescopii is a white-hued star in the southern constellation of Telescopium. This is an A-type main sequence star with an apparent visual magnitude of +5.03. It is approximately 158 light years from Earth and is a member of the Beta Pictoris Moving Group of stars that share a common motion through space. It is moving through the Galaxy at a speed of 23.7 km/s relative to the Sun.

<span class="mw-page-title-main">Methods of detecting exoplanets</span>

Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty of detecting such a faint light source, the light from the parent star causes a glare that washes it out. For those reasons, very few of the exoplanets reported as of April 2014 have been observed directly, with even fewer being resolved from their host star.

<span class="mw-page-title-main">Debris disk</span> Disk of dust and debris in orbit around a star

A debris disk, or debris disc, is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks are found around stars with mature planetary systems, including at least one debris disk in orbit around an evolved neutron star. Debris disks can also be produced and maintained as the remnants of collisions between planetesimals, otherwise known as asteroids and comets.

Gliese 849, or GJ 849, is a small, solitary star in the equatorial constellation of Aquarius. It has a reddish hue and is invisible to the naked eye with an apparent visual magnitude of 10.41. The distance to this star is 28.8 light-years based on parallax, but it is drifting closer to the Sun with a radial velocity of −15.3 km/s. It has a pair of confirmed gas giant companions.

<span class="mw-page-title-main">Epsilon Eridani b</span> Gas giant orbiting Epsilon Eridani

Epsilon Eridani b, also known as AEgir [sic], is an exoplanet approximately 10.5 light-years away orbiting the star Epsilon Eridani, in the constellation of Eridanus. The planet was discovered in 2000, and as of 2023 remains the only confirmed planet in its planetary system. It orbits at around 3.5 AU with a period of around 7.6 years, and has a mass around 0.6 times that of Jupiter. As of 2023, both the Extrasolar Planets Encyclopaedia and the NASA Exoplanet Archive list the planet as 'confirmed'.

Gliese 86 is a K-type main-sequence star approximately 35 light-years away in the constellation of Eridanus. It has been confirmed that a white dwarf orbits the primary star. In 1998 the European Southern Observatory announced that an extrasolar planet was orbiting the star.

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<span class="mw-page-title-main">Beta Pictoris b</span> Super Jupiter orbiting Beta Pictoris

Beta Pictoris b (abbreviated as β Pic b) is an exoplanet orbiting the young debris disk A-type main sequence star Beta Pictoris located approximately 63 light-years (19.4 parsecs, or 6×1014 km) away from Earth in the constellation of Pictor. It has a mass around 13 Jupiter masses and a radius around 46% larger than Jupiter's. It orbits at 9 AU from Beta Pictoris, which is about 3.5 times farther than the orbit of Beta Pictoris c. It orbits close to the plane of the debris disk orbiting the star, with a low eccentricity and a period of 20–21 years.

<span class="mw-page-title-main">PZ Telescopii</span> Star in the constellation Telescopium

PZ Telescopii, also known as HD 174429 or simply PZ Tel, is a young star in the constellation Telescopium. Based on parallax measurements, it is located at a distance of 154 light-years from the Sun. The star is drifting closer with a radial velocity of −4 km/s. It is too faint to be visible to the naked eye and is classified as a BY Draconis variable that ranges in apparent visual magnitude from 8.33 down to 8.63 over a period of 22.581 hours. It is one of the closest and hence brightest pre-main-sequence stars to Earth.

Beta Pictoris c is the second exoplanet discovered orbiting the young star Beta Pictoris, located approximately 63 light-years away from Earth in the constellation of Pictor. Its mass is around nine times that of Jupiter, and it orbits at around 2.7 astronomical units (AU) from Beta Pictoris, about 3.5 times closer to its parent star than Beta Pictoris b. It has an orbital period of 1,200 days. The orbit of Beta Pictoris c is moderately eccentric, with an eccentricity of 0.24.

References

  1. 1 2 3 4 5 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, S2CID   18759600.
  2. 1 2 3 4 Simon, M.; Schaefer, G. H. (2011). "MEASURED DIAMETERS OF TWO F STARS IN THE β PIC MOVING GROUP". The Astrophysical Journal. 743 (2): 158. arXiv: 1109.3483 . Bibcode:2011ApJ...743..158S. doi:10.1088/0004-637X/743/2/158. S2CID   16107676.
  3. 1 2 Sepulveda, Aldo G.; et al. (October 2022), "The Directly Imaged Exoplanet Host Star 51 Eridani is a Gamma Doradus Pulsator", The Astrophysical Journal, 938 (1): 49, arXiv: 2205.01103 , Bibcode:2022ApJ...938...49S, doi: 10.3847/1538-4357/ac9229 , S2CID   248505903, 49.
  4. ↑ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv: 1606.08053 . Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID   119231169.
  5. 1 2 3 Mamajek, Eric E.; Bell, Cameron P. M. (2014). "On the age of the β Pictoris moving group". Monthly Notices of the Royal Astronomical Society. 445 (3): 2169–80. arXiv: 1409.2737 . Bibcode:2014MNRAS.445.2169M. doi:10.1093/mnras/stu1894.
  6. ↑ Rajan, Abhijith; et al. (May 2017), "Characterizing 51 Eri b from 1 to 5μm: a partly-cloudy exoplanet", The Astronomical Journal, 154 (1): 10, arXiv: 1705.03887 , Bibcode:2017AJ....154...10R, doi: 10.3847/1538-3881/aa74db , S2CID   119189199.
  7. ↑ McCarthy, Kyle; White, Russel J. (June 2012), "The Sizes of the Nearest Young Stars", The Astronomical Journal, 143 (6): 14, arXiv: 1201.6600 , Bibcode:2012AJ....143..134M, doi:10.1088/0004-6256/143/6/134, S2CID   118538522, 134.
  8. ↑ Paunzen, E.; et al. (July 2014), "Investigating the possible connection between λ Bootis stars and intermediate Population II type stars", Astronomy & Astrophysics, 567: 8, arXiv: 1406.3936 , Bibcode:2014A&A...567A..67P, doi:10.1051/0004-6361/201423817, S2CID   56332289, A67.
  9. ↑ Bortle, John E. (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope . Sky Publishing Corporation. Retrieved 14 October 2021.
  10. 1 2 Montet, Benjamin T.; Bowler, Brendan P.; Shkolnik, Evgenya L.; Deck, Katherine M.; Wang, Ji; Horch, Elliott P.; Liu, Michael C.; Hillenbrand, Lynne A.; Kraus, Adam L.; Charbonneau, David (2015). "Dynamical Masses of Young M Dwarfs: Masses and Orbital Parameters of Gj 3305 Ab, the Wide Binary Companion to the Imaged Exoplanet Host 51 Eri". The Astrophysical Journal. 813 (1): L11. arXiv: 1508.05945 . Bibcode:2015ApJ...813L..11M. doi:10.1088/2041-8205/813/1/L11. S2CID   33496969.
  11. ↑ Wagman 2003, p. 144.
  12. ↑ Wagman 2003, pp. 6–7.
  13. ↑ Wagman 2003, p. 403.
  14. ↑ McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (2012). "Fundamental Parameters and Infrared Excesses of Hipparcos Stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–57. arXiv: 1208.2037 . Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. S2CID   118665352.
  15. ↑ Riviere-Marichalar, P.; Barrado, D.; Montesinos, B.; Duchêne, G.; Bouy, H.; Pinte, C.; et al. (2014). "Gas and dust in the beta Pictoris moving group as seen by the Herschel Space Observatory". Astronomy & Astrophysics. 565: 11. arXiv: 1404.1815 . Bibcode:2014A&A...565A..68R. doi:10.1051/0004-6361/201322901. S2CID   56161891. A68.
  16. ↑ Pecaut, Mark J.; Mamajek, Eric E. (2013). "Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-main-sequence Stars". The Astrophysical Journal Supplement. 208 (1): 22. arXiv: 1307.2657 . Bibcode:2013ApJS..208....9P. doi:10.1088/0067-0049/208/1/9. S2CID   119308564.
  17. 1 2 "Hot Jupiter-esque Discovery Hints at Planet Formation". W. M. Keck Observatory. Kamuela, Hawaii. 13 August 2015. Archived from the original on 2015-12-26. Retrieved 14 August 2015.
  18. ↑ Feltman, Rachel (August 13, 2015). "Newly discovered, Jupiter-like planet may sit in a solar system much like our own". Speaking of Science. The Washington Post . Retrieved 14 August 2015.
  19. ↑ Gary, Stuart (14 August 2015). "Small alien world most Jupiter-like planet ever seen". ABC Science. ABC. Retrieved 14 October 2021.
  20. 1 2 3 Rosa, Robert J. De; et al. (2019), "An Updated Visual Orbit of the Directly Imaged Exoplanet 51 Eridani b and Prospects for a Dynamical Mass Measurement with Gaia", The Astronomical Journal, 159: 1, arXiv: 1910.10169 , doi: 10.3847/1538-3881/ab4da4 , S2CID   204838112
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