Astronomy:HD 154556

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Short description: Star in the constellation of Apus
HD 154556
location of HD 154556 in red
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Apus
Right ascension  17h 12m 19.93421s[1]
Declination −70° 43′ 15.8963″[1]
Apparent magnitude (V) 6.21±0.01[2]
Characteristics
Evolutionary stage subgiant
Spectral type K1 IV CN3[3]
U−B color index +1.04[4]
B−V color index +1.06[4]
Astrometry
Radial velocity (Rv)−24±0.4[5] km/s
Proper motion (μ) RA: +49.060[1] mas/yr
Dec.: −78.104[1] mas/yr
Parallax (π)14.3386 ± 0.0224[1] mas
Distance227.5 ± 0.4 ly
(69.7 ± 0.1 pc)
Absolute magnitude (MV)+2.10[6]
Details
Mass1.25[7] M☉
Radius6.35±0.32[8] R☉
Luminosity19.7±0.1[1] L☉
Surface gravity (log g)2.90±0.25[9] cgs
Temperature4,677[10] K
Metallicity [Fe/H]+0.04±0.09[9] dex
Rotational velocity (v sin i)<1[11] km/s
Age3.52+0.36−0.37[1] Gyr
Other designations
CD−70°1498, CPD−70°2361, GC 23140, HD 154556, HIP 84158, HR 6357, SAO 257472[12]
Database references
SIMBADdata

HD 154556, also known as HR 6357, is a solitary orange-hued star located in the southern circumpolar constellation Apus. It has an apparent magnitude of 6.21,[2] placing it near the limit for naked eye visibility. The star is located relatively close at a distance of 228 light years based on Gaia DR3 parallax measurements,[1] but it is drifter closer with a heliocentric radial velocity of −24 km/s.[5] At its current distance, HD 154556's brightness is diminished by 0.26 magnitudes due to interstellar dust.[13] It has an absolute magnitude of +2.10.[6]

HD 154556 has a stellar classification of K1 IV CN3,[3] indicating that it is an evolved K-type subgiant with a moderate abundance of cyano radicals in its spectrum, making it a CN star. It has 1.25 times the mass of the Sun[7] and is calculated to be 3.52 billion years old,[1] having expanded to 6.35 times the radius of the Sun.[8] It now radiates 19.7 times the luminosity of the Sun[1] from its enlarged photosphere at an effective temperature of 4,677 K.[10] It has a near solar metallicity[9] and spins slowly with a projected rotational velocity lower than 1 km/s.[11]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations −90° to −53°. Bibcode: 1975mcts.book.....H. 
  4. ↑ 4.0 4.1 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode: 1966CoLPL...4...99J. 
  5. ↑ 5.0 5.1 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. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode: 2006AstL...32..759G. 
  6. ↑ 6.0 6.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 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. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A. 
  8. ↑ 8.0 8.1 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants". Astronomy & Astrophysics 426 (1): 297–307. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode: 2004A&A...426..297K. 
  9. ↑ 9.0 9.1 9.2 Randich, S.; Gratton, R.; Pallavicini, R.; Pasquini, L.; Carretta, E. (August 1999). "Lithium in population I subgiants". Astronomy and Astrophysics 348: 487–500. ISSN 0004-6361. Bibcode: 1999A&A...348..487R. 
  10. ↑ 10.0 10.1 Allende Prieto, C.; Lambert, D. L. (December 1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics 352: 555–562. ISSN 0004-6361. Bibcode: 1999A&A...352..555A. 
  11. ↑ 11.0 11.1 De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars V: Southern stars". Astronomy & Astrophysics 561: A126. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode: 2014A&A...561A.126D. 
  12. ↑ "HD 154556". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+154556. 
  13. ↑ 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. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
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