HD 197911 (HIP 102274) is a bluish-white hued star in the deep northern constellation of Cepheus, close to the border with Draco and Cygnus. With an apparent magnitude of 7.669, it is too faint to be seen by the naked eye under most conditions, but readily visible using binoculars.[4] The star is located some 3,020 light-years (930 parsecs) distant according to Gaia EDR3 parallax measurements, but is moving closer to the Solar System at a heliocentric radial velocity of −3.8±3.5 km/s.
  | |
| Observation data Epoch J2000[1] Equinox J2000[1] | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 20h 43m 21.60554s |
| Declination | +63° 12′ 32.8418″ |
| Apparent magnitude (V) | 7.669[2] |
| Characteristics | |
| Spectral type | B5[2] |
| B−V color index | −0.01[1] |
| J−H color index | −0.109[1] |
| J−K color index | −0.107[1] |
| Astrometry | |
| Radial velocity (Rv) | −3.80±3.5 km/s |
| Proper motion (μ) | RA: −13.478[3] mas/yr Dec.: -3.025[3] mas/yr |
| Parallax (π) | 1.0802 ± 0.0214 mas[3] |
| Distance | 3,020 ± 60 ly (930 ± 20 pc) |
| Details[2] | |
| Mass | 6.320±0.316 M☉ |
| Radius | 9.218±0.461 R☉ |
| Other designations | |
| Database references | |
| SIMBAD | HD 197911 |
The star appears close to the reflection nebula and H II region[5] Sh2-130, alongside the A0-type star HD 197809 and G5-type star SAO 18999,[6] though the latter two stars are located much closer to Earth at 469 ly (144 pc)[7] and 198 ly (61 pc),[8] respectively. The nebula itself is situated at a distance of 600 pc (2,000 ly).[6]
Properties and origin
editHD 197911 is a massive B-type star with the spectral type B5, a mass 6.3 times that of the Sun and 9.2 times the radius. It is a runaway star traversing space at a peculiar velocity of 56.69 km/s. The star is thought to have once been part of a binary system, from which it was ejected as its companion ended its life in a supernova.[9]
Initially, the star was thought to have originated in an OB association called the Cepheus OB2 association, which it left 2–3 million years ago, when the association was 3–4 million years old. This aligned with the age of the Cepheus bubble, an annular structure of infrared emission, providing compelling evidence for the binary-supernova scenario, that is, that it was blasted out of a binary system by a companion going supernova.[10]
However, with updated astrometric data, it is now considered more likely that it formed in either Alessi-Teutsch 5 or NGC 7160, two star clusters that are each 12.5 and 9.0 million years old. Both origins are consistent with the initially proposed scenario.[9]
References
edit- ^ a b c d e "HD 197911". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 5 November 2024.
- ^ a b c Kervella, Pierre; Arenou, Frédéric; Mignard, François; Thévenin, Frédéric (2019). "Stellar and substellar companions of nearby stars from Gaia DR2". Astronomy & Astrophysics. 623. EDP Sciences: A72. arXiv:1811.08902. doi:10.1051/0004-6361/201834371. ISSN 0004-6361. Record for this source at VizieR.
- ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ Zarenski, Ed (2004). "Limiting Magnitude in Binoculars" (PDF). Cloudy Nights. Archived (PDF) from the original on 21 July 2011. Retrieved 6 May 2011.
- ^ Sharpless, Stewart (1959). "A Catalogue of H II Regions". The Astrophysical Journal Supplement Series. 4. American Astronomical Society: 257. doi:10.1086/190049. ISSN 0067-0049.
- ^ a b "Sh 2-130". galaxymap.org. Retrieved 5 November 2024.
- ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ a b Bhat, A.; Irrgang, A.; Heber, U. (2022). "The origin of early-type runaway stars from open clusters". Astronomy & Astrophysics. 663. EDP Sciences: A39. arXiv:2204.01594. doi:10.1051/0004-6361/202142993. ISSN 0004-6361.
- ^ Hoogerwerf, R.; de Bruijne, J. H. J.; de Zeeuw, P. T. (2001). "On the origin of the O and B-type stars with high velocities". Astronomy & Astrophysics. 365 (2). EDP Sciences: 49–77. doi:10.1051/0004-6361:20000014. ISSN 0004-6361.