HD 123657

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HD 123657
(BY Boötis)
Boötes constellation map.svg
Red circle.svg
Location of BY Boö (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension 14h 07m 55.756s[1]
Declination 43° 51′ 16.03″[1]
Apparent magnitude (V) 5.28[2] (4.98-5.33[3])
Spectral type M4.5III[4]
U−B color index 1.66[2]
B−V color index 1.58[2]
R−I color index 1.66[2]
Variable type LB[4]
Radial velocity (Rv) -36.24[5] km/s
Proper motion (μ) RA: 11.63[1] mas/yr
Dec.: -30.08[1] mas/yr
Parallax (π) 6.36 ± 0.26[1] mas
Distance 510 ± 20 ly
(157 ± 6 pc)
Absolute magnitude (MV) −0.90[6]
Radius 70[7] R
Luminosity 1,380[8] L
Temperature 3,500[8] K
Metallicity [Fe/H] −0.03[9] dex
Other designations
BY Boötis, JP11 2471, AG+44° 1162, GSC 03040-00969, 2MASS J14075576+4351160, TYC 3040-969-1, BD+44° 2325, HD 123657, N30 3210, UBV M 19995, CSV 7099, HIC 69038, PLX 3214, UBV 12478, DO 34564, HIP 69038, PMC 90-93 957, FK5 1368, HR 5299, PPM Star Catalogue 53940, GC 19084, IRAS 14059+4405, RAFGL 1680, AAVSO 1403+44, GCRV 8285, IRC +40253, SAO 44901.
Database references

HD 123657, or BY Boötis, is a variable star of magnitude 4.98–5.33V. This makes it a dim naked eye star. The star is located near the end of the handle of the Big Dipper, but just within the boundaries of the constellation Boötes.

It is a slow irregular red giant variable star with a range of less than half a magnitude. It is over a thousand times as luminous as the sun, only 3,500 K but with a large expanded atmosphere.


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  2. ^ a b c d 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: 0. Bibcode:2002yCat.2237....0D. 
  3. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S. 
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  6. ^ Park, Sunkyung; Kang, Wonseok; Lee, Jeong-Eun; Lee, Sang-Gak (2013). "Wilson-Bappu Effect: Extended to Surface Gravity". The Astronomical Journal. 146 (4): 73. arXiv:1307.0592Freely accessible. Bibcode:2013AJ....146...73P. doi:10.1088/0004-6256/146/4/73. 
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  8. ^ a b Blum, R. D.; Ramírez, Solange V.; Sellgren, K.; Olsen, K. (2003). "Really Cool Stars and the Star Formation History at the Galactic Center". The Astrophysical Journal. 597: 323. arXiv:astro-ph/0307291Freely accessible. Bibcode:2003ApJ...597..323B. doi:10.1086/378380. 
  9. ^ Marrese, P. M.; Boschi, F.; Munari, U. (2003). "High resolution spectroscopy over lambda lambda 8500-8750 Å for GAIA. IV. Extending the cool MK stars sample". Astronomy and Astrophysics. 406 (3): 995. Bibcode:2003A&A...406..995M. doi:10.1051/0004-6361:20030647.