Pi2 Columbae is a multiple star system in the southern constellation of Columba, near the southern constellation border with Pictor. Its name is a Bayer designation that is Latinized from π2 Columbae, and abbreviated Pi2 Col or π2 Col. This system is white-hued and dimly visible to the naked eye as a point of light with a combined apparent visual magnitude of 5.50.[2] Based upon an annual parallax shift of 12.76 mas as seen from Earth,[1] this system is located about 256 ly (78 pc) from the Sun. They are receding with a heliocentric radial velocity of +31 km/s.[4]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Columba |
| Right ascension | 06h 07m 52.860s[1] |
| Declination | −42° 09′ 14.55″[1] |
| Apparent magnitude (V) | 5.50[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | A0 V + A[3] |
| B−V color index | +0.00[2] |
| Astrometry | |
| Radial velocity (Rv) | +31.0±3.7[4] km/s |
| Proper motion (μ) | RA: −10.221 mas/yr[1] Dec.: −16.956 mas/yr[1] |
| Parallax (π) | 12.7569±0.0522 mas[1] |
| Distance | 256 ± 1 ly (78.4 ± 0.3 pc) |
| Absolute magnitude (MV) | +1.17[5] |
| Details | |
| Mass | 2.34±0.04[1] M☉ |
| Radius | 2.23±0.05[1] R☉ |
| Luminosity | 38.7±0.6[1] L☉ |
| Surface gravity (log g) | 4.064±0.005[1] cgs |
| Temperature | 9,646±46[1] K |
| Rotational velocity (v sin i) | 274[6] km/s |
| Age | 370±79[1] Myr |
| Other designations | |
| π2 Col, CD−42°2351, GC 7816, HD 42303, HIP 29064, HR 2181, SAO 217730, WDS J06079-4209AB[7] | |
| Database references | |
| SIMBAD | data |
The primary star is an A-type main-sequence star of spectral class A0 V,[3] an estimated 370 million years old[1] and spinning rapidly with a projected rotational velocity of 274 km/s.[6] It has 2.34 times the mass of the Sun and 2.23 times the Sun's radius.[1] The star is radiating 38.7 times the luminosity of the Sun from its photosphere at an effective temperature of 9,646 K.[1]
The system is a source of X-ray emission with a luminosity of 184.3×1020 W, which is considered unusual since A-type stars are not expected to display magnetic activity.[3] An A-class companion has been reported at an angular separation of 0.1 arc seconds.[8] The existence of this star has been disputed by other authors.[9]
There are additional possible companions: a 15th-magnitude star 6.6″ away; and a 20th-magnitude star 103″ away. These have a common proper motion although they are too far from the primary for any possible orbital motion to be detected. They are estimated to have masses of 0.48 M☉ and 0.12 M☉ respectively.[9]
References
edit- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Vallenari, A.; et al. (Gaia collaboration) (2023), "Gaia Data Release 3. Summary of the content and survey properties", Astronomy and Astrophysics, 674: A1, arXiv:2208.00211, Bibcode:2023A&A...674A...1G, doi:10.1051/0004-6361/202243940, S2CID 244398875 Gaia DR3 record for this source at VizieR.
- 1 2 3 Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C.
- 1 2 3 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.
- 1 2 de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
- ↑ Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035, S2CID 119108982.
- 1 2 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ↑ "pi02 Col". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-28.
- ↑ 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.
- 1 2 Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5.