38 Boötis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 49m 18.67062s[1] |
| Declination | +46° 06′ 58.3369″[1] |
| Apparent magnitude (V) | 5.76[2] |
| Characteristics | |
| Evolutionary stage | subgiant[3] |
| Spectral type | F6 IVs[4] |
| B−V color index | 0.482±0.002[2] |
| Astrometry | |
| Radial velocity (Rv) | −4.5±0.2[2] km/s |
| Proper motion (μ) | RA: –6.404[1] mas/yr Dec.: −78.073[1] mas/yr |
| Parallax (π) | 20.7166 ± 0.0638 mas[1] |
| Distance | 157.4 ± 0.5 ly (48.3 ± 0.1 pc) |
| Absolute magnitude (MV) | 2.31[2] |
| Details | |
| Mass | 1.60±0.04[5] M☉ |
| Radius | 2.51+0.04 −0.08[1] R☉ |
| Luminosity | 9.511±0.039[1] L☉ |
| Surface gravity (log g) | 3.92±0.02[5] cgs |
| Temperature | 6,591±63[5] K |
| Metallicity [Fe/H] | 0.11±0.05[5] dex |
| Rotational velocity (v sin i) | 9.8[6] km/s |
| Age | 1.74+0.19 −0.10[5] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
38 Boötis is a single[8] star in the northern constellation of Boötes,[1] located approximately 157 light years from the Sun.[1] It has the traditional name Merga[9] /ˈmɜːrɡə/ and the Bayer designation h Boötis; 38 Boötis is the star's Flamsteed designation. This object is visible to the naked eye as a dim, yellow-white hued star with an apparent visual magnitude of 5.76.[2] It is moving closer to the Earth with a heliocentric radial velocity of −4.5 km/s.[2]
This is a sharp-lined ('s') subgiant[3] star with a stellar classification of F6 IVs,[4] which indicates it has consumed the hydrogen at its core and is evolving off the main sequence. It is about 1.7[5] billion years old and is spinning with a relatively low projected rotational velocity of 10 km/s,[6] as indicated by the sharp lines. The star has 1.6[5] times the mass of the Sun and 2.5[1] times the Sun's radius. It is radiating 9.5[1] times the luminosity of the Sun from its photosphere at an effective temperature of 6,591 K.[5]
Nomenclature[edit]
It has the traditional name Merga, occasionally spelled Marrha[10][11] or in full El Mara el Musalsela,[11] from the Arabic المرأة المسلسلة al-mar'ah al-musalsalah "the chained woman". Another occasional name was Falx Italica,[11] from the Latin falx ītalica "billhook". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[12] to catalogue and standardize proper names for stars. The WGSN approved the name Merga for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.[9]
References[edit]
- ^ a b c d e f g h i j k 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 f 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.
- ^ a b do Nascimento, J. D. Jr.; et al. (July 2003), "On the link between rotation, chromospheric activity and Li abundance in subgiant stars", Astronomy and Astrophysics, 405 (2): 723–731, arXiv:astro-ph/0307196, Bibcode:2003A&A...405..723D, doi:10.1051/0004-6361:20030633, S2CID 1106754.
- ^ a b Gray, R. O.; et al. (2001), "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars", The Astronomical Journal, 121 (4): 2148, Bibcode:2001AJ....121.2148G, doi:10.1086/319956.
- ^ a b c d e f g h Aguilera-Gómez, Claudia; et al. (June 2018), "Lithium abundance patterns of late-F stars: an in-depth analysis of the lithium desert", Astronomy & Astrophysics, 614: 15, arXiv:1803.05922, Bibcode:2018A&A...614A..55A, doi:10.1051/0004-6361/201732209, S2CID 62799777, A55.
- ^ a b Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377[permanent dead link]
- ^ "38 Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 12, 2019.
- ^ 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.
- ^ a b Naming Stars, IAU.org, retrieved 16 December 2017.
- ^ Bakich, Michael E. (1995), The Cambridge Guide to the Constellations, Cambridge University Press, ISBN 9780521449212.
- ^ a b c Dolan, Christopher J, Merga, retrieved 2016-06-24.
- ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
