38 Virginis

38 Virginis

Observation data Epoch J2000.0       Equinox J2000.0
Constellation	Virgo [1]
Right ascension	12h 53m 11.15678s [2]
Declination	−03° 33′ 11.1513″ [2]
Apparent magnitude  (V)	6.135±0.037 [3]
Characteristics
Evolutionary stage	main sequence [2]
Spectral type	F6V [4]
B−V color index	0.49 [4]
Astrometry
Radial velocity (Rv)	−7.30±0.32 [5] km/s
Proper motion (μ)	RA: −262.971 mas/yr [2] Dec.: −3.649 mas/yr [2]
Parallax (π)	29.9081±0.0377  mas [2]
Distance	109.1 ± 0.1  ly (33.44 ± 0.04  pc)
Details
Mass	1.18±0.12 [4]   M☉
Radius	1.45±0.07 [4]   R☉
Luminosity	3.48 [note 1]   L☉
Temperature	6557±96 [4]   K
Metallicity [Fe/H]	+0.07 [4]   dex
Age	1.9+0.6 −0.7 [4]   Gyr
Other designations
BD−02 3593, HD 111998, HIP 62875, HR 4891, WDS J12532-0333AB [6]
Database references
SIMBAD	data

38 Virginis is an F-type main sequence star in the constellation of Virgo. With an apparent magnitude of 6.135, ^[3] it is very close to the average threshold for naked eye visibility, and can only be viewed from sufficiently dark skies, far from light pollution. ^[7] It is around 109.1 light years distant from the Earth. ^[2]

Nomenclature

The name 38 Virginis derives from the star being the 38th star in order of right ascension catalogued in the constellation Virgo by Flamsteed in his star catalogue. The designation b of 38 Virginis b derives from the order of discovery and is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet. ^[8] In the case of 38 Virginis, only one was discovered, which was designated b. ^[4]

Characteristics

38 Virginis is an F-type main sequence star that is approximately 118% the mass of and 145% the radius of the Sun. It has a temperature of 6557 K and is about 1.9 billion years old. In comparison, the Sun is about 4.6 billion years old ^[9] and has a temperature of 5778 K. ^[10]

The star is metal-rich, with a metallicity ([Fe/H]) of 0.07 dex, or 117% the solar amount. Its luminosity (L_☉) is 3.48 times that of the Sun.

A companion star is cataloged in the CCDM at a separation of half an arcsecond. ^[11]

Planetary system

The 38 Virginis planetary system ^[4]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	4.51±0.5  MJ	1.82±0.07	825.9±6.2	0.03±0.04	—	—

The star is known to host one exoplanet, 38 Virginis b, discovered in 2016. It has a mass of around 4.5 times that of the planet Jupiter, an orbital period of 825.9 days (2.261 years) and a relatively low eccentricity out of any long-period giant exoplanet discovered, with an eccentricity of 0.03. ^[4]

The planet lies within the host star's habitable zone. As of 2024 ^[update] , it is the only known planet around a F-type star that is always orbiting inside the habitable zone, as opposed to an orbit that never or just occasionally crosses the HZ. ^[12]

Notes

1. From ${\displaystyle {\begin{smallmatrix}L=4\pi R^{2}\sigma T_{\rm {eff}}^{4}\end{smallmatrix}}}$, where ${\displaystyle {\begin{smallmatrix}L\end{smallmatrix}}}$ is the luminosity, ${\displaystyle {\begin{smallmatrix}R\end{smallmatrix}}}$ is the radius, ${\displaystyle {\begin{smallmatrix}T_{\rm {eff}}\end{smallmatrix}}}$ is the effective surface temperature and ${\displaystyle {\begin{smallmatrix}\sigma \end{smallmatrix}}}$ is the Stefan–Boltzmann constant.

References

1. 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. XHIP record for this object at VizieR.
2. 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.
3. Paunzen, E. (2015-08-01). "A new catalogue of Strömgren-Crawford uvbyβ photometry". Astronomy and Astrophysics. 580: A23. arXiv: 1506.04568 . Bibcode:2015A&A...580A..23P. doi:10.1051/0004-6361/201526413. ISSN   0004-6361.
4. Borgniet, S.; et al. (2017). "Extrasolar planets and brown dwarfs around AF-type stars. IX. The HARPS southern sample". Astronomy and Astrophysics. 599. A57. arXiv: 1608.08257 . Bibcode:2017A&A...599A..57B. doi:10.1051/0004-6361/201628805. S2CID   118723455.
5. 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.
6. "38 Virginis". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2018-10-19.
7. "Limiting Magnitude | COSMOS". astronomy.swin.edu.au. Retrieved 2025-06-01.
8. Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv: 1012.0707 [astro-ph.SR].
9. Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today . Retrieved 19 February 2011.
10. Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
11. J. Dommanget; et al. (February 2002), Catalog of Components of Double & Multiple Stars, Observations et Travaux, Societe Astronomique de France
12. Patel, Shaan D.; Cuntz, Manfred; Weinberg, Nevin N. (September 2024). "Statistics and Habitability of F-type Star–Planet Systems". The Astrophysical Journal Supplement Series. 274 (1): 20. arXiv: 2407.15826 . Bibcode:2024ApJS..274...20P. doi: 10.3847/1538-4365/ad65eb . ISSN   0067-0049.