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">Iota Aquarii</span> B-type main sequence star in the constellation Aquarius

Iota Aquarii, Latinised from ι Aquarii, is the Bayer designation for a binary star system in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent magnitude of +4.279. Based upon parallax measurements made during the Hipparcos mission, the distance to this star is around 175 light-years. The system is drifting closer to the Sun with a radial velocity of −10 km/s.

30 Aquarii is a single star located about 301 light years away from the Sun in the zodiac constellation of Aquarius. 30 Aquarii is its Flamsteed designation. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.56. The star is moving further from the Earth with a heliocentric radial velocity of 40 km/s.

Tau<sup>4</sup> Eridani Binary star system in the constellation Eridanus

Tau4 Eridani is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.65. The distance to this star can be estimated using the parallax method, which yields a value of roughly 300 light years.

14 Eridani is a star in the equatorial Eridanus constellation. It has an apparent visual magnitude of 6.143 and is moving closer to the Sun with a radial velocity of around −5 km/s. The measured annual parallax shift is 29.26 mas, which provides an estimated distance of about 121 light years. Proper motion studies indicate that this is an astrometric binary.

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.

Iota Eridani is a solitary star in the constellation Eridanus. It is visible to the naked eye with an apparent magnitude of 4.11. With an annual parallax shift of 0.02165 arcseconds, it lies at an estimated distance of about 151 light years.

Pi Eridani, Latinized from π Eridani, is a star in the constellation Eridanus. It has an apparent visual magnitude of 4.40, which is bright enough to be seen on a dark, clear night. Based upon parallax measurements, it is located roughly 480 light years from the Sun.

17 Eridani is a single star in the equatorial constellation of Eridanus. It has the Bayer designation v Eridani, while 17 Eridani is the Flamsteed designation. This object is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.74. It is moving further from the Earth with a heliocentric radial velocity of around +15 km/s.

Psi Eridani, Latinized from ψ Eridani, is a star in the constellation Eridanus. With an apparent visual magnitude is 4.81, it can be seen with the naked eye on a clear, dark night. Based upon an annual parallax shift of 4.41 milliarcseconds, it is located roughly 740 light-years away from the Sun.

15 Eridani is a binary star system in the equatorial constellation of Eridanus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.875. Based upon parallax measurements, the system is located around 260 light years away from the Sun. It is moving further from the Earth with a heliocentric radial velocity of 24 km/s.

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.

45 Eridani is a single star located around 700 light years away from the Sun in the equatorial constellation of Eridanus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.91. This body is moving away from the Earth with a heliocentric radial velocity of +15 km/s.

26 Hydrae is a binary star system located 334 light years away from the Sun in the equatorial constellation of Hydra. It is visible to the naked eye as a faint, yellow-hued point of light with a combined apparent visual magnitude of 4.77, just a few degrees away from Alphard. The system is moving closer to the Earth with a leisurely radial velocity of -1 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.

11 Serpentis is a single star in the constellation of Serpens, located 271 light years away from the Sun. It has the Bayer designation A1 Serpentis, 11 Serpentis is the Flamsteed designation. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.497. It is moving closer to the Earth with a heliocentric radial velocity of −16 km/s.

<span class="mw-page-title-main">HD 28375</span> Star in the constellation Taurus

HD 28375 is a single star in the equatorial constellation of Taurus, near the southern constellation border with Eridanus. It was previously known by the Flamsteed designation 44 Eridani, although the name has fallen out of use because constellations were redrawn, placing the star out of Eridanus and into Taurus. The star is blue-white in hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.53. The distance to this star is approximately 480 light-years based on parallax. It is drifting further away with a radial velocity of 18 km/s, after having come to within an estimated 249 light-years some 3.7 million years ago.

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

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  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.