Nu Pictoris

ν Pictoris, Latinized as Nu Pictoris, is a binary star system in the southern Pictor constellation. It is visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.60.[2] The system is located around 157 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +7 km/s.[2]

ν Pictoris
Location of ν Pictoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pictor
Right ascension 06h 22m 55.82671s[1]
Declination −56° 22′ 11.8909″[1]
Apparent magnitude (V) 5.60[2]
Characteristics
Spectral type A1mA3-A9[3]
U−B color index 0.12[4]
B−V color index 0.26[4]
Astrometry
Radial velocity (Rv)+6.7±2.9[2] km/s
Proper motion (μ) RA: −39.96[1] mas/yr
Dec.: −20.13[1] mas/yr
Parallax (π)20.72 ± 0.56 mas[1]
Distance157 ± 4 ly
(48 ± 1 pc)
Absolute magnitude (MV)+2.18[2]
Orbit[5]
Period (P)452+13
−16 d
Semi-major axis (a)5.9+1.6
−0.9 mas
Eccentricity (e)0.20+0.35
−0.19
Inclination (i)116+12
−10°
Longitude of the node (Ω)53+166
−16°
Periastron epoch (T)2448660
Argument of periastron (ω)
(secondary)		109±53°
Details
Radius2.19+0.12
−0.10[6] R☉
Luminosity15.4±0.4[6] L☉
Temperature7,733+170
−203[6] K
Other designations
ν Pic, CPD−56°1072, GC 8274, HD 45229, HIP 30342, HR 2320, SAO 234473, TYC 8542-1469-1[7]
Database references
SIMBADdata

Hipparcos satellite astrometry showed that ν Pictoris moved in a way that was not consistent with the proper motion and annual parallax of a single star. The unusual measurements were not readily identifiable as being due to orbital motion, and it was referred to as having a stochastic solution to its astrometry. Later analysis derived an orbit, although nothing is known about the companion except its approximate mass and motion about the visible star.[5]

The pair orbit each other with a period of 452 days and an eccentricity of 0.2.[5] The primary, component A, is a metal-lined Am star with a stellar classification of A1mA3-A9.[3] It has 2.2 times the radius of the Sun and is radiating 15 times the Sun's luminosity from its photosphere at an effective temperature of 7,733 K.[6] The secondary, component B, has around one fourth the mass of the primary.[8][5] The system is a source for X-ray emission, which is most likely coming from the companion.[9]

References
  1. 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. Vizier catalog entry
  2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  3. Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 1. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode:1975mcts.book.....H.
  4. Feinstein, A. (1974). "Photoelectric UBVRI observations of AM stars". Astronomical Journal. 79: 1290. Bibcode:1974AJ.....79.1290F. doi:10.1086/111675.
  5. Goldin, A. (2007). "Astrometric Orbits for Hipparcos Stochastic Binaries". The Astrophysical Journal Supplement Series. 173 (1): 137–142. arXiv:0706.0361. Bibcode:2007ApJS..173..137G. doi:10.1086/520513. S2CID 119586069.
  6. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  7. "nu. Pic". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 28 December 2016.
  8. Goldin, A.; Makarov, V. V. (September 2006). "Unconstrained Astrometric Orbits for Hipparcos Stars with Stochastic Solutions". The Astrophysical Journal Supplement Series. 166 (1): 341–350. arXiv:astro-ph/0606293. Bibcode:2006ApJS..166..341G. doi:10.1086/505939. S2CID 15673734.
  9. Schröder, C.; Schmitt, J. H. M. M. (November 2007). "X-ray emission from A-type stars". Astronomy and Astrophysics. 475 (2): 677–684. Bibcode:2007A&A...475..677S. doi:10.1051/0004-6361:20077429.
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