Astronomy:HD 154556

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Short description: Star in the constellation of Apus
HD 154556
Apus constellation map.svg
Red circle.svg
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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