Wikipedia

HD 28780

HD 28780, also known as HR 1440, is a solitary white-hued star[14] located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.91,[2] making it faintly viisble to the naked eye under ideal conditions. Gaia DR3 parallax measurements imply a distance of 488 light-years,[1] and it is currently drifting closer with a heliocentric radial velocity of −22.6 km/s.[7] At its current distance, HD 28780's brightness is diminished by 0.33 magnitudes due to interstellar extinction[15] and it has an absolute magnitude of +0.26.[8]

HD 28780
Location of HD 28780 on the map (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Camelopardalis
Right ascension 04h 36m 24.19802s[1]
Declination +64° 15′ 41.7609″[1]
Apparent magnitude (V) 5.91±0.01[2]
Characteristics
Evolutionary stage main sequence star[3]
Spectral type A1 V[4] or A1 III[5]
U−B color index −0.02[6]
B−V color index −0.03[6]
Astrometry
Radial velocity (Rv)−22.6±1.8[7] km/s
Proper motion (μ) RA: −25.398 mas/yr[1]
Dec.: −8.119 mas/yr[1]
Parallax (π)6.6785 ± 0.0412 mas[1]
Distance488 ± 3 ly
(149.7 ± 0.9 pc)
Absolute magnitude (MV)+0.26[8]
Details
Mass2.48±0.08[9] M☉
Radius3.79+0.12
−0.13[10] R☉
Luminosity101±2[1] L☉
Surface gravity (log g)3.67+0.06
−0.08[10] cgs
Temperature9,616+134
−132[3] K
Metallicity [Fe/H]−0.21[11] dex
Rotational velocity (v sin i)41.3±2.0[12] km/s
Age300+21
−19[9] Myr
Other designations
AG+64°277, BD+63°515, FK5 2336, GC 5574, HD 28780, HIP 21452, HR 1440, SAO 13196[13]
Database references
SIMBADdata

HD 28780 has a stellar classification of A1 V,[4] indicating that it is an ordinary A-type main-sequence star that is generating energy via hydrogen fusion at its core. However, Abt & Morell (1995) gave a classification of A1 III,[5] indicating that it is an evolved A-type giant star that has exhausted hydrogen fusion at its core. At the age of 300 million years,[9] HD 28780 has completed 80.2% of its main sequence lifetime.[3] It has 2.48 times the mass of the Sun[9] and a slightly enlarged radius 3.79 times larger than the Sun's.[10] The star radiates 101 times the luminosity of the Sun[1] from its photosphere at an effective temperature of 9,616 K.[3] HD 28780 is metal deficient with an iron abundance 61.7% that of the Sun's ([Fe/H] = −0.21)[11] and unlike most hot stars, it spins modestly with a projected rotational velocity of 41.3 km/s.[12]

References

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  1. ^ a b c d e f g 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.
  2. ^ a b Oja, T. (August 1991). "UBV photometry of stars whose positions are accurately known. VI". Astronomy and Astrophysics Supplement Series. 89: 415. Bibcode:1991A&AS...89..415O. ISSN 0365-0138.
  3. ^ a b c d Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars IV: Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. eISSN 1432-0746. ISSN 0004-6361. S2CID 55586789.
  4. ^ a b Cowley, A.; Cowley, C.; Jaschek, M.; Jaschek, C. (April 1969). "A study of the bright stars. I. A catalogue of spectral classifications". The Astronomical Journal. 74: 375. Bibcode:1969AJ.....74..375C. doi:10.1086/110819. ISSN 0004-6256. S2CID 121555804.
  5. ^ a b Abt, Helmut A.; Morrell, Nidia I. (July 1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182. ISSN 0067-0049. S2CID 120495962.
  6. ^ a b Oja, T. (April 1983). "UVB photometry of FK4 and FK4 Supplement stars". Astronomy and Astrophysics Supplement Series. 52: 131–134. Bibcode:1983A&AS...52..131O. ISSN 0365-0138.
  7. ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
  8. ^ a b Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
  9. ^ a b c d Grosbol, P. J. (June 1978). "Space velocities and ages of nearby early-type stars". Astronomy and Astrophysics Supplement Series. 32: 409–421. Bibcode:1978A&AS...32..409G. ISSN 0365-0138.
  10. ^ a b c Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881. hdl:1721.1/124721. S2CID 166227927.
  11. ^ a b Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. eISSN 1432-0746. ISSN 0004-6361. S2CID 131780028.
  12. ^ a b Ramella, M.; Boehm, C.; Gerbaldi, M.; Faraggiana, R. (January 1989). ""Normal" main sequence A0 stars of low rotational velocity". Astronomy and Astrophysics. 209: 233–243. Bibcode:1989A&A...209..233R. ISSN 0004-6361.
  13. ^ "HD 28780". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved July 20, 2023.
  14. ^ Eggleton, P. P.; Tokovinin, A. A. (11 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. eISSN 1365-2966. ISSN 0035-8711. S2CID 14878976.
  15. ^ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society. 472 (4): 3805–3820. arXiv:1709.01160. Bibcode:2017MNRAS.472.3805G. doi:10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711. S2CID 118879856.
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