Rho2 Eridani

Last updated
ρ2 Eridani
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 03h 02m 42.28856s [1]
Declination −07° 41 07.7165 [1]
Apparent magnitude  (V)5.32 [2]
Characteristics
Spectral type K0 III [3]
U−B color index +0.73 [2]
B−V color index +0.94 [2]
Astrometry
Radial velocity (Rv)26.38±0.23 [4]  km/s
Proper motion (μ)RA: +49.30 [1]   mas/yr
Dec.: −5.42 [1]   mas/yr
Parallax (π)12.32 ± 1.23  mas [1]
Distance 260 ± 30  ly
(81 ± 8  pc)
Absolute magnitude  (MV)0.830 [5]
Details
Mass 2.53 [5]   M
Radius 9 [4]   R
Luminosity 45.7 [4]   L
Surface gravity (log g)2.6 [4]   cgs
Temperature 4,864 [4]   K
Metallicity [Fe/H]0.19 [5]   dex
Rotational velocity (v sin i)0.0 [4]  km/s
Other designations
ρ2 Eridani, ρ2 Eri, 9 Eridani, BD−08°568, HD  18953, HIP 14168, HR 917, SAO  130254. [6]
Database references
SIMBAD data

Rho2 Eridani is a star located in the constellation Eridanus. It forms an asterism with Rho1 and Rho3 Eridani, south of Cetus, in the upper north east portion of Eridanus. The star has an apparent visual magnitude of 5.32, [2] which indicates it is visible to the naked eye on a clear, dark night. Based upon parallax measurements made with the Hipparcos satellite, this star is roughly 260  light years away from the Sun.

This is an evolved K-type giant star with a stellar classification of K0 III. [3] It is a red clump giant on the horizontal branch of the Hertzsprung–Russell diagram, indicating that is it now generating energy through the thermonuclear fusion of helium at its core. [5] The star has 2.5 times the mass of the Sun and has expanded to 9 times the Sun's radius. As such, it is radiating nearly 46 times the solar luminosity from its outer atmosphere at an effective temperature of 4,864 K. [4]

There is a magnitude 9.7 companion star at an angular separation of 1.8. Most likely the pair form a binary star system. [7] At least one of the stars appears to be a source of X-ray emission. [8] The X-ray band flux is 3.65×10−15 W·m−2. [9]

Related Research Articles

<span class="mw-page-title-main">Gamma Eridani</span> Variable star in the constellation Eridanus

Gamma Eridani, formally named Zaurak, is a variable star in the constellation of Eridanus. It is visible to the naked eye with an apparent visual magnitude that varies around 2.9, and lies at a distance of about 203 light years from the Sun, as determined by the Hipparcos astrometry satellite.

<span class="mw-page-title-main">Nu Aurigae</span> Variable star in the constellation Auriga

Nu Aurigae, Latinised from ν Aurigae, is the Bayer designation for a star in the northern constellation of Auriga. It is visible to the naked eye with an apparent visual magnitude of 3.96 and is approximately 220 light-years distant from the Earth. This is an evolved giant star with a stellar classification of G9.5 III. It is a red clump star, which indicates that it is generating energy through the fusion of helium at its core. The outer envelope has expanded to 19 times the radius of the Sun and cooled to 4,571 K, giving it the characteristic yellow-hued glow of a G-type star. It shines with 135 times the luminosity of the Sun.

68 Aquarii is a single star located 270 light years away from the Sun in the zodiac constellation of Aquarius. 68 Aquarii is its Flamsteed designation, though it also bears the Bayer designation of g2 Aquarii. It is visible to the naked eye as a dim, yellow-hued star with an apparent visual magnitude of 5.24. The object is moving further from the Earth with a heliocentric radial velocity of +24.5 km/s.

31 Boötis is a single star in the northern constellation of Boötes, located 470 light years from the Sun. It is visible to the naked eye as a faint, yellow-hued star with an apparent visual magnitude of 4.86. The object is moving closer to the Earth with a heliocentric radial velocity of −16.5 km/s. It was known to be part of a constellation between Virgo and Boötes named Mons Maenalus, it was also the brightest star in the constellation.

<span class="mw-page-title-main">Omega Persei</span> Star in the constellation Perseus

Omega Persei (ω Persei) is a solitary, orange-hued star in the northern constellation of Perseus. The star is faintly visible to the naked eye with an apparent visual magnitude of +4.6. Based upon an annual parallax shift of 11.32 mas as seen from the Earth, the star is about 288 light years from the Sun.

HD 173780 is a single star in the northern constellation Lyra, near the southern constellation border with Hercules. It is an orange-hued star that is faintly visible to the naked eye with an apparent visual magnitude of +4.84. This object is located at a distance of approximately 237 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −17 km/s.

HD 15920 is a single star in the northern constellation of Cassiopeia. It has a yellow hue and is visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.17. This object is located at a distance of approximately 268 light years from the Sun based on parallax, but it is drifting closer with a radial velocity of −4 km/s.

<span class="mw-page-title-main">52 Cygni</span> Binary star system in the constellation Cygnus

52 Cygni is a giant star in the northern constellation of Cygnus with an apparent magnitude of 4.22. Based on its Hipparcos parallax, it is about 291 light-years (89 pc) away.

24 Vulpeculae is a single, yellow-hued star in the northern constellation of Vulpecula. It is faintly visible to the naked eye with an apparent visual magnitude of 5.30. The distance to this star can be estimated from its annual parallax shift of 7.9700±0.0674, which yields a separation of roughly 409 light years. It is moving further away with a heliocentric radial velocity of +15 km/s.

1 Serpentis is a red giant in the constellation Virgo with an apparent magnitude of 5.5. It is a red clump giant, a cool horizontal branch star that is fusing helium in its core. It has expanded to over 13 times the radius of the Sun and although it is cooler at 4,581 K it is 77 times more luminous. It is 322 light years away.

24 Cephei is a single, yellow-hued star in the northern circumpolar constellation of Cepheus. With an apparent visual magnitude of 4.79, it is faintly visible to the naked eye. The distance to this star, based upon an annual parallax shift of 8.3965 mas, is around 388 light years. It is moving closer with a heliocentric radial velocity of −17 km/s.

Xi Coronae Borealis is a binary star system in the northern constellation of Corona Borealis. It is visible to the naked eye with a combined apparent visual magnitude of 4.85. Based upon an annual parallax shift of 17.78 mas as seen from the Earth, it is located about 183 light years from the Sun.

39 Eridani is a wide binary star system in the equatorial constellation of Eridanus. It is visible to the naked eye as a faint, orange-hued star with a combined apparent visual magnitude of 4.87. As of 2015, the components had an angular separation of 6.4″ along a position angle of 143°. The system is moving further from the Sun with a heliocentric radial velocity of +7 km/s.

HD 81799 is a suspected astrometric binary star system in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.69. The distance to this system, as determined from an annual parallax shift of 19.9 mas, is 164 light years. It is moving further away from the Earth with a heliocentric radial velocity of 29 km/s. The system has a relatively high rate of proper motion, traversing the celestial sphere at the rate of 233±19 mas/yr along a position angle of 136°.

37 Tauri is a single, orange-hued star in the zodiac constellation of Taurus. It can be seen with the naked eye, having an apparent visual magnitude of 4.36. A magnitude 10.01 visual companion has an angular separation of 134.30″ on a position angle of 138.6°, as of 2003. Based on an annual parallax shift of 17.43±0.21 mas, 37 Tauri is about 187 light years away. It is moving further from the Sun with a heliocentric radial velocity of 9.5 km/s.

Eta Normae, Latinized from η Normae, is a single star in the southern constellation of Norma. It is visible to the naked eye as a faint, yellow-hued star with an apparent visual magnitude of 4.65. The distance to this star is about 219 light years, based on parallax. The Gamma Normids radiate from a position near this star.

<span class="mw-page-title-main">HD 12055</span> Candidate binary star system in the constellation Phoenix

HD 12055 is a candidate astrometric binary star system in the southern constellation of Phoenix, near the eastern constellation border with Eridanus. It is yellow in hue and is visible to the naked eye with an apparent visual magnitude of 4.82. The system is located at a distance of approximately 249 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +13 km/s.

69 Virginis is a single star in the zodiac constellation of Virgo, located about 259 light years away. It is visible to the naked eye as a faint orange-hued star with an apparent visual magnitude of 4.76, although it is a suspected variable that may range in magnitude from 4.75 down to 4.79. This object is moving closer to the Earth with a heliocentric radial velocity of −13 km/s. The light from this star is polarized due to intervening interstellar dust.

Rho1 Eridani , is a star located in the constellation Eridanus. It forms an asterism with the stars Rho2 and Rho3 Eridani, south of Cetus, in the upper north east portion of Eridanus. The star has an apparent visual magnitude of 5.75, which indicates it is faintly visible to the naked eye on a clear, dark night. Based upon parallax measurements made with the Hipparcos satellite, this star is roughly 320 light years away from the Sun. Judging from changes to its proper motion, there is a chance that this is an astrometric binary.

Rho3 Eridani, Latinized from ρ3 Eridani, is a star located in the constellation Eridanus. It forms an asterism with Rho1 and Rho2 Eridani, south of Cetus, in the upper north east portion of Eridanus. The star has an apparent visual magnitude of 5.26, which is bright enough to be seen with the naked eye on a dark, clear night. The distance to this star, as determined via the parallax method, is about 136 light years.

References

  1. 1 2 3 4 5 van Leeuwen, F. (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 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  3. 1 2 Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
  4. 1 2 3 4 5 6 7 Massarotti, Alessandro; et al. (January 2008), "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi: 10.1088/0004-6256/135/1/209 .
  5. 1 2 3 4 Zhao, G.; et al. (2001), "High-Resolution Spectroscopic Observations of Hipparcos Red Clump Giants: Metallicity and Mass Determinations", The Astrophysical Journal, 551 (1): L85, Bibcode:2001ApJ...551L..85Z, doi:10.1086/319832, S2CID   119700315.
  6. "rho02 Eri". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2016-10-12.
  7. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society , 389 (2): 869–879, arXiv: 0806.2878 , Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID   14878976.
  8. Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009), "XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources", The Astrophysical Journal Supplement, 184 (1): 138–151, arXiv: 0910.3229 , Bibcode:2009ApJS..184..138H, doi:10.1088/0067-0049/184/1/138, S2CID   119267456.
  9. Schwope, A.; et al. (2000), "The ROSAT Bright Survey: II. Catalogue of all high-galactic latitude RASS sources with PSPC countrate CR > 0.2 s−1", Astronomische Nachrichten, 321 (1): 1–52, arXiv: astro-ph/0003039 , Bibcode:2000AN....321....1S, doi:10.1002/(SICI)1521-3994(200003)321:1<1::AID-ASNA1>3.0.CO;2-C.