Sigma Puppis

Sigma Puppis
Location of σ Puppis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Puppis
Right ascension 07h 29m 13.83263s[1]
Declination −43° 18′ 05.1674″[1]
Apparent magnitude (V) 3.25[2]
Characteristics
Spectral type K5 III[3]
U−B color index +1.77[2]
B−V color index +1.52[2]
Astrometry
Radial velocity (Rv)+87.3[4] km/s
Proper motion (μ) RA: +199.39 mas/yr[1]
Dec.: −61.828 mas/yr[1]
Parallax (π)17.0234 ± 0.5614 mas[1]
Distance192 ± 6 ly
(59 ± 2 pc)
Absolute magnitude (MV)−0.50[5]
Orbit[6]
Period (P)257.8 days
Eccentricity (e)0.17
Periastron epoch (T)20418.6
Argument of periastron (ω)
(secondary)		349.3°
Semi-amplitude (K1)
(primary)		18.6 km/s
Details
σ Pup A
Mass1.65[7] M☉
Radius43.7[4] R☉
Luminosity344[7] L☉
Surface gravity (log g)1.51[7] cgs
Temperature4,077±4[7] K
Rotational velocity (v sin i)3.0[8] km/s
Other designations
σ Pup, Sigma Pup, CPD−43  1499, FK5 1194, GC 10040, HD 59717, HIP 36377, HR 2878, SAO 218755, WDS J07292-4318A[9]
Database references
SIMBADdata

Sigma Puppis, Latinized from σ Puppis, is a binary star system in the southern constellation Puppis. It has an apparent visual magnitude of 3.25,[2] which is bright enough to be visible to the naked eye at night from the Southern Hemisphere. Through a telescope, it appears as a bright, orange-hued star with a nearby white companion.[10] Parallax measurements indicate this star is located at a distance of about 192 light-years (59 parsecs) from Earth.[1]

A light curve for Sigma Puppis, adapted from Otero (2007)[11]

This is a spectroscopic binary system,[9] consisting of an orbiting pair of stars that have not been individually resolved with a telescope. Their orbital period is 257.8 days and the eccentricity is 0.17.[6] The pair form an eclipsing binary of the Beta Lyrae type and a period of 130.5 days, or one half of their orbital period. The eclipse of the primary component causes a decline of 0.04 of a magnitude, while the secondary eclipse reduces the magnitude by 0.03.[11][12]

The combined stellar classification is K5 III,[3] which matches the spectrum of a giant star. The primary is 44 times larger than the Sun[4] and 340 times more luminous. Its surface has an effective temperature of 4,077 K,[7] giving it the orange hue of a K-type star.[13] It shows the behavior of a slow irregular variable.[11][12]

In addition to its binary components, Sigma Puppis has a more distant companion that has a matching proper motion, suggesting that it may be gravitationally bound to the binary. This magnitude 8.5[10] star is at an angular separation of 22.4 arcseconds with a position angle of 74° from Sigma Puppis, which is equivalent to a projected separation of 1,200 AU.[14] In 1970, American astronomer Olin J. Eggen suggested that Sigma Puppis belonged to a moving group of stars that share a similar motion through space, and thereby a common origin. It served as the eponym for this, the σ Puppis group.[15] The existence of this group was later brought into question.[16]

  1. ^ a b c d e 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 c d Cite error: The named reference clpl4_99 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference wood was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference pdaov15_121 was invoked but never defined (see the help page).
  7. ^ a b c d e Cite error: The named reference Ayres2023 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference aaa382_1016 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference plotner_mann2007 was invoked but never defined (see the help page).
  11. ^ a b c Cite error: The named reference oejvs72_1_1 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference atnf was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference burnham1978 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference pasp83_493_251 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference aaa362_563 was invoked but never defined (see the help page).