Rho Orionis

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ρ Orionis
Orion constellation map.svg
Red circle.svg
Location of ρ Orionis (circled)
Observation data
Epoch J2000.0        Equinox J2000.0
Constellation Orion
Right ascension 05h 13m 17.48015s [1]
Declination +02° 51′ 40.5479″ [1]
Apparent magnitude  (V)+4.44 [2]
Characteristics
Spectral type K0 III [3]
U−B color index +1.13 [2]
B−V color index +1.19 [2]
Astrometry
Radial velocity (Rv)+40.5 [4]  km/s
Proper motion (μ)RA: +0.83 [1]   mas/yr
Dec.: +3.91 [1]   mas/yr
Parallax (π)9.32 ± 0.94 [1]   mas
Distance approx. 350  ly
(approx. 110  pc)
Absolute magnitude  (MV)−0.65 [5]
Details [6]
Mass 2.67  M☉
Radius 25 [7]   R☉
Luminosity 251  L☉
Surface gravity (log g)2.4 [8]   cgs
Temperature 4,533  K
Metallicity [Fe/H]0.06 [8]   dex
Age 650  Myr
Orbit [9]
Period (P)1031.4 days
Semi-major axis (a)6.9 mas [note 1]
Eccentricity (e)0.1
Inclination (i)122.8°
Longitude of the node (Ω)242.6°
Periastron epoch (T)2426182.46
Argument of periastron (ω)
(secondary)		17.9°
Semi-amplitude (K1)
(primary)		8.70 km/s
Other designations
ρ Ori, 17 Orionis, BD+02° 888, HD  33856, HIP  24331, HR  1698, SAO  112528
Database references
SIMBAD data

Rho Orionis, Latinized from ρ Orionis, is the Bayer designation for an orange-hued binary star system in the equatorial constellation of Orion. It is visible to the naked eye with an apparent visual magnitude of +4.44. [2] The star shows an annual parallax shift of 9.32  mas due to the orbital motion of the Earth, which provides a distance estimate of roughly 350  light years from the Sun. It is moving away from the Sun with a radial velocity of +40.5 km/s. [4] About 2.6 million years ago, Rho Orionis made its perihelion passage at a distance of around 10 ly (3.1 pc). [10]

This is a single-lined spectroscopic binary system with an orbital period of 2.8 years and an eccentricity of 0.1. [9] The visible component is an evolved giant star of type K with a stellar classification of K0 III. [3] Its measured angular diameter is 2.19±0.02  mas , [11] which, at its estimated distance yields a physical size of about 25 times the radius of the Sun. [7] It has 2.67 times the mass of the Sun and is about 650 million years old. The star is radiating 251 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,533 K. [6]

Notes

  1. ↑ This is the photocentric semi-major axis, from the motion shown by the observed "star" relative to distant objects, and in practice relative to the barycentre. This is always smaller than the orbital semi-major axis, dramatically smaller when the primary star is much more massive than the secondary or when it is not much brighter.

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Zeta Volantis

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10 Andromedae, abbreviated 10 And, is an astrometric binary star system in the northern constellation of Andromeda. 10 Andromedae is the Flamsteed designation. It has an apparent visual magnitude of approximately 5.81, which means it is faintly visible to the naked eye. Based upon an annual parallax shift of 6.6 mas, it is located 492 light years away. The system is moving toward the Earth with a heliocentric radial velocity of −1.1 km/s.

7 Arietis is a binary star system in the northern constellation of Aries. 7 Arietis is the Flamsteed designation. The pair have a combined apparent visual magnitude of 5.76, making it faintly visible to the naked eye from dark suburban skies. Based upon an annual parallax shift of 5.85 mas, it is approximately 560 light-years distant from the Earth, give or take a 40 light-year margin of error.

66 Aquilae, abbreviated 66 Aql, is a fifth-magnitude star in the constellation of Aquila. 66 Aquilae is its Flamsteed designation. It is visible to the naked eye, having an apparent visual magnitude of 5.44. The star shows an annual parallax shift of 4.4 mas, which provides a distance estimate of around 730 light years. It is moving closer to the Earth with a heliocentric radial velocity of −30 km/s. The motion of the star over time suggests some displacement, which may indicate it is a close binary system.

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Phi1 Cancri, Latinized from φ1 Cancri, is a solitary, orange-hued star in the constellation Cancer. It is faintly visible to the naked eye with an apparent visual magnitude of +5.57. Based upon an annual parallax shift of 8.74 mas, it is approximately 370 light years from the Sun.

6 Canis Minoris is a star in the equatorial constellation of Canis Minor, located around 570 light years away from the Sun. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of +4.55. This object is moving closer to the Earth with a heliocentric radial velocity of −16.3 km/s. Kinematically, it is a member of an outlying group belonging to the Ursa Major flow of the Sirius supercluster.

Upsilon<sup>1</sup> Cassiopeiae Star in the constellation Cassiopeia

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Tau Puppis

Tau Puppis is a star in the southern constellation of Puppis. It has an apparent visual magnitude of +2.95 and is located at a distance of about 182 light-years from Earth. This is a spectroscopic binary star system, with the presence of the secondary component being revealed by the shifts of absorption lines in the spectrum resulting from the Doppler effect. The two components orbit each other with a period of 1,066.0 days (2.9 years) and a low eccentricity of 0.090.

Nu Orionis

Nu Orionis is a binary star system in the northeastern part of the constellation Orion. It should not be confused with the variable star NU Orionis. Nu Orionis has an apparent visual magnitude of 4.42, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 0.00632 arcseconds, the distance to this system is roughly 520 light years.

Upsilon Draconis is a binary star system in the northern circumpolar constellation of Draco. It is faintly visible to the naked eye with an apparent visual magnitude of 4.83. Based upon an annual parallax shift of 9.48 mas as measured from Earth, it is located around 340 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.02 due to interstellar dust.

φ Eridani is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.55. The distance to this star, as determined using the parallax method, is around 154 light years.

Omega Eridani is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude is 4.37. The distance to this star, as determined by the parallax method, is around 235 light years.

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RR Ursae Minoris, or RR UMi, is a binary star system in the northern circumpolar constellation of Ursa Minor. It can be viewed with the naked eye, typically having an apparent visual magnitude of around 4.710. Based upon an annual parallax shift of 10.0 mas as seen from Earth's orbit, it is located 330 light years away. The system is moving further from the Sun with a heliocentric radial velocity of +6 km/s.

Phi3 Ceti is a solitary, orange-hued star in the equatorial constellation of Cetus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.31. Based upon an annual parallax shift of 5.92 mas as seen from Earth, it is located roughly 550 light years from the Sun, give or take 30 light years.

Delta Mensae is a binary star system in the southern constellation of Mensa. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.69. Based upon an annual parallax shift of 7.70 mas as seen from the Earth, it is 420 light years from the Sun.

3 Piscis Austrini, also known as HD 201901, is a suspected astrometric binary star system that, despite its Flamsteed designation, is actually located in the constellation Microscopium. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.41. The system is moving closer to the Earth with a heliocentric radial velocity of −46 km/s. It is following a highly elliptical orbit around the Galactic Center, moving between a pericenter of 2.6 kpc out to an apocenter of 7.6 kpc, with an orbital eccentricity of 0.49.

π Geminorum is a star located in the constellation Gemini, to the north of Castor. With an apparent visual magnitude of 5.14, it is faintly visible to the naked eye on a dark night. Based upon an annual parallax|shift of 4.93 mas, Pi Geminorum is located roughly 660 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an interstellar absorption factor of 0.033 due to interstellar dust.

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.
  2. 1 2 3 4 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. 1 2 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 05: 0. Bibcode:1999MSS...C05....0H.
  4. 1 2 Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics. 430: 165. arXiv: astro-ph/0409579 . Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272.
  5. ↑ Smith, Graeme H.; Shetrone, Matthew D. (2000). "CaII K Emission-Line Asymmetry among Red Giants Detected by the ROSAT Satellite". The Publications of the Astronomical Society of the Pacific. 112 (776): 1320. Bibcode:2000PASP..112.1320S. doi: 10.1086/316634 .
  6. 1 2 Luck, R. Earle (2015). "Abundances in the Local Region. I. G and K Giants". The Astronomical Journal. 150 (3): 88. arXiv: 1507.01466 . Bibcode:2015AJ....150...88L. doi:10.1088/0004-6256/150/3/88.
  7. 1 2 Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN   3-540-29692-1 . The radius (R*) is given by:
  8. 1 2 Soubiran, C.; Le Campion, J.-F.; Cayrel de Strobel, G.; Caillo, A. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv: 1004.1069 , Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247.
  9. 1 2 Ren, S. (2013), "Hipparcos Photocentric Orbits of 72 Single-lined Spectroscopic Binaries", The Astronomical Journal, 145 (3): 81, Bibcode:2013AJ....145...81R, doi:10.1088/0004-6256/145/3/81
  10. ↑ Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics, 575: 13, arXiv: 1412.3648 , Bibcode:2015A&A...575A..35B, doi:10.1051/0004-6361/201425221, A35.
  11. ↑ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431: 773–777, Bibcode:2005A&A...431..773R, doi: 10.1051/0004-6361:20042039
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