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 163 light years from the Sun based on parallax,[6] and is drifting further away with a radial velocity of +7 km/s.[2]
Characteristics
Binarity
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 was known about the companion except its approximate mass and motion about the visible star.[7]
The companion was directly detected in 2026 using interferometric data taken in 2024 by the GRAVITY instrument aboard the Very Large Telescope, revealing it to be a K-type main-sequence star. The projected separation of 0.17 au is much smaller than the orbital semi-major axis, which could suggest that the projected separation is much smaller than the actual separation, a possibility further supported by the nearly edge-on orientation of the orbit. A more exotic hypothesis is that Nu Pictoris is a triple system, on which the companion responsible for the astrometric anomalies is, in fact, a third undetected star, either a white dwarf or red dwarf.[4]
The pair orbit each other with a period of 452 days,[7] a semi-major axis of 1.56 au,[4] and an eccentricity of 0.2.[7]
Physical characteristics
The primary, component A, is a metal-lined Am star with a stellar classification of A1mA3-A9.[3] It has 1.7 times the Sun's mass,[4] 1.85 times the radius of the Sun[4] and is radiating 15 times the Sun's luminosity from its photosphere[8] at an effective temperature of 7,700 K.[4] The secondary, component B, has 0.8 times the Sun's mass, 0.72 times the Sun's radius, and a temperature of 4,800 K.[4] The system is a source for X-ray emission and exhibits stellar flares, both of which are coming from the companion.[4]
References
- 1 2 3 4 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
- 1 2 3 4 5 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.
- 1 2 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.
- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Waisberg, Idel; Klein, Ygal; Katz, Boaz (2026-08-18). "Hidden Companions to Intermediate-mass Stars. XXXIX. Discovery of a 0.8 M☉ Companion to the Flaring Am Star Nu Pictoris". Research Notes of the AAS. 10 (8): 240. doi:10.3847/2515-5172/ae9a71. ISSN 2515-5172.
- 1 2 Feinstein, A. (1974). "Photoelectric UBVRI observations of AM stars". Astronomical Journal. 79: 1290. Bibcode:1974AJ.....79.1290F. doi:10.1086/111675.
- 1 2 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.
- 1 2 3 4 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.
- 1 2 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.
- ↑ Stassun, Keivan G.; et al. (2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467.
- ↑ Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031.
- 1 2 Balona, L. A. (2019). "Evidence for spots on hot stars suggests major revision of stellar physics". Monthly Notices of the Royal Astronomical Society. 490 (2): 2112. arXiv:1910.01584. Bibcode:2019MNRAS.490.2112B. doi:10.1093/mnras/stz2808.
- ↑ "nu. Pic". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 28 December 2016.
