Astronomy:45 Herculis

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Short description: Star in the constellation Hercules
45 Herculis
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An ultraviolet band light curve for V776 Herculis, adapted from Burke and Barr (1981)[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Hercules
Right ascension  16h 47m 46.41942s[2]
Declination +05° 14′ 48.2789″[2]
Apparent magnitude (V) 5.22[3]
Characteristics
Spectral type A1 Vp Si[4] or B9p Cr[5]
U−B color index +0.005[6]
B−V color index −0.025[6]
Variable type α2 CVn[7]
Astrometry
Radial velocity (Rv)−13.13±0.09[8] km/s
Proper motion (μ) RA: −18.802[2] mas/yr
Dec.: −38.735[2] mas/yr
Parallax (π)8.1955 ± 0.2169[2] mas
Distance400 ± 10 ly
(122 ± 3 pc)
Absolute magnitude (MV)−0.18[9]
Orbit[8]
Period (P)99.51 ± 0.10 d
Eccentricity (e)0.445 ± 0.020
Argument of periapsis (ω)
(primary)		167.1 ± 4.2°
Semi-amplitude (K1)
(primary)		4.75 ± 0.12 km/s
Details
Mass2.85±0.11[10] M☉
Radius4.3[11] R☉
Luminosity129.7[8] L☉
Surface gravity (log g)3.55[12] cgs
Temperature9,400[8] K
Metallicity [Fe/H]0.10[12] dex
Rotation4.116476 ± 0.000022
Rotational velocity (v sin i)35.5[13] km/s
Age351–469[8] Myr
Other designations
l Her, 45 Her, V776 Herculis, BD+05°3272, HD 151525, HIP 82216, HR 6234, SAO 121865, WDS 16478+0515[14]
Database references
SIMBADdata

45 Herculis is a binary variable star in the northern constellation Hercules. It has the Bayer designation l Herculis and the variable star designation V776 Herculis. The Flamsteed designation for this star comes from the publication Historia Coelestis Britannica by John Flamsteed. It is the 45th star in Flamsteed list of stars in the constellation Hercules, and is visible to the naked eye with a baseline apparent visual magnitude of 5.22.[3] Parallax measurements show this star to be about 400 light-years away from the Solar System.[2] It is moving closer to the Earth with a heliocentric radial velocity of −16 km/s.[15]

Cowley et at. (1969) assigned this object a classification of B9p Cr,[5] while Abt and Morrell (1995) found a class of A1 Vp Si.[4] Both indicate this is a late B- or early A-type chemically peculiar, or Ap star, with abundance anomalies in chromium or silicon. It is classified as a magnetic Ap star, although its magnetic field is unusually weak for a star of this class.[8] It is an Alpha2 Canum Venaticorum variable that ranges in visual magnitude from 5.21 down to 5.27.[7] The star has 2.9[10] times the mass of the Sun and 4.9[11] times the Sun's radius. It is radiating 120[9] times the Sun's luminosity from its photosphere at an effective temperature of 9,333 K.[12]

Although 45 Herculis was long thought to be a solitary star,[16] a 2023 study confirmed that 45 Herculis is a single-lined spectroscopic binary. The pair of stars orbit each other every 99.51 days on a moderately eccentric orbit. The secondary star is likely a low-mass star.[8]

References

  1. ↑ Burke, E. W. Jr.; Barr, T. H. (June 1981). "Photometric UBV period study of eight AP stars". Publications of the Astronomy Society of the Pacific 93: 344–350. doi:10.1086/130836. Bibcode: 1981PASP...93..344B. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  3. ↑ 3.0 3.1 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237. Bibcode: 2002yCat.2237....0D. 
  4. ↑ 4.0 4.1 Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement 99: 135. doi:10.1086/192182. Bibcode: 1995ApJS...99..135A. 
  5. ↑ 5.0 5.1 Cowley, A. et al. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications". Astronomical Journal 74: 375–406. doi:10.1086/110819. Bibcode: 1969AJ.....74..375C. 
  6. ↑ 6.0 6.1 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode: 1986EgUBV........0M. 
  7. ↑ 7.0 7.1 Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 Kochukhov, O.; Gürsoytrak Mutlay, H.; Amarsi, A. M.; Petit, P.; Mutlay, I.; Gürol, B. (2023). "Surface structure of 45 Hercules: An otherwise unremarkable Ap star with a surprisingly weak magnetic field". Monthly Notices of the Royal Astronomical Society 521 (3): 3480–3499. doi:10.1093/mnras/stad720. Bibcode: 2023MNRAS.521.3480K. 
  9. ↑ 9.0 9.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. 
  10. ↑ 10.0 10.1 Netopil, Martin; Paunzen, Ernst; Huemmerich, Stefan; Bernhard, Klaus (July 2017). "An Investigation of the Rotational Properties of Magnetic Chemically Peculiar Stars". Monthly Notices of the Royal Astronomical Society 468 (3): 2745–2756. doi:10.1093/mnras/stx674. Bibcode: 2017MNRAS.468.2745N. 
  11. ↑ 11.0 11.1 Shulyak, D. et al. (2014). "Interferometry of chemically peculiar stars: Theoretical predictions versus modern observing facilities". Monthly Notices of the Royal Astronomical Society 443 (2): 1629. doi:10.1093/mnras/stu1259. Bibcode: 2014MNRAS.443.1629S. 
  12. ↑ 12.0 12.1 12.2 Wolff, Sidney Carne (October 1967). "A Spectroscopic and Photometric Study of the AP Stars". Astrophysical Journal Supplement 15: 21. doi:10.1086/190162. Bibcode: 1967ApJS...15...21W. 
  13. ↑ Royer, F. et al. (October 2002). "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i". Astronomy and Astrophysics 393: 897–911. doi:10.1051/0004-6361:20020943. Bibcode: 2002A&A...393..897R. 
  14. ↑ "45 Her". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=45+Her. 
  15. ↑ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode: 1953GCRV..C......0W. 
  16. ↑ 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. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode: 2008MNRAS.389..869E. 



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