7 Vulpeculae
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Vulpecula |
| Right ascension | 19h 29m 20.8974s[1] |
| Declination | 20° 16′ 47.0583″[1] |
| Apparent magnitude (V) | 6.337[2] |
| Characteristics | |
| Spectral type | B4–5 III–IVe[3] |
| U−B color index | −0.585[2] |
| B−V color index | −0.157[2] |
| Astrometry | |
| Radial velocity (Rv) | −38.0±4.3[4] km/s |
| Proper motion (μ) | RA: 2.555±0.069[1] mas/yr Dec.: −15.383±0.071[1] mas/yr |
| Parallax (π) | 3.4729 ± 0.0479 mas[1] |
| Distance | 940 ± 10 ly (288 ± 4 pc) |
| Absolute magnitude (MV) | −1.66+0.44 −0.51[3] |
| Orbit[3] | |
| Period (P) | 69.30±0.07 d |
| Eccentricity (e) | 0.161±0.035 |
| Periastron epoch (T) | 2,454,248.1±2.7 HJD |
| Argument of periastron (ω) (secondary) | 247±16° |
| Semi-amplitude (K1) (primary) | 8.9±0.4 km/s |
| Details[3] | |
| 7 Vul A | |
| Mass | 5.5±0.5 M☉ |
| Radius | 5.2 R☉ |
| Surface gravity (log g) | 3.75±0.02 cgs |
| Temperature | 15,600±200 K |
| Rotational velocity (v sin i) | 300±30 km/s |
| Age | 50–80 Myr |
| 7 Vul B | |
| Mass | 0.50 – 0.77[3] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
7 Vulpeculae is a binary star system approximately 940[1] light years away in the northern constellation of Vulpecula.[5] It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.34.[2] The system is moving closer to the Earth with a heliocentric radial velocity of −38 km/s.[4]
This is a single-lined spectroscopic binary star system with an orbital period of 69.3 days and an eccentricity of 0.16.[3] The visible component is a Be star with a stellar classification of B4–5 III–IVe that appears to be nearing the end of its main sequence lifetime. It shows a rapid rotation rate with a projected rotational velocity of 300 km/s, which is just below the estimated critical velocity of 367 km/s.[3]
There is a small variability in the magnitude of this star that occurs over 0.559 days this is likely the rotation period of the primary star.[2]
The nature of the companion is unknown, but based upon its mass it may be a K- or M-type star. However, it could be a white dwarf that has previously undergone a mass transfer event with the now visible component. Because of the lack of X-ray emission from the system, a third possibility is that the companion is a naked He star that has been stripped of its hydrogen envelope.[3]
References
- ^ a b c d e f 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.
- ^ a b c d e Harmanec, P.; et al. (2020). "A new study of the spectroscopic binary 7 Vul with a Be star primary". Astronomy and Astrophysics. 639. Table A.1. arXiv:2005.11089. Bibcode:2020A&A...639A..32H. doi:10.1051/0004-6361/202037964.
- ^ a b c d e f g h Vennes, S.; et al. (2011). "On the nature of the Be star HR 7409 (7 Vul)". Monthly Notices of the Royal Astronomical Society. 413 (4): 2760–2766. arXiv:1101.2622. Bibcode:2011MNRAS.413.2760V. doi:10.1111/j.1365-2966.2011.18350.x.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b 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.
- ^ a b "7 Vul". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 28 August 2012.
External links
- 7 Vulpeculae on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
