Sigma Puppis

Sigma Puppis
	Location of σ Puppis (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Puppis
Right ascension	07h 29m 13.83049s
Declination	–43° 18′ 05.1597″
Apparent magnitude (V)	3.25
Characteristics
Spectral type	K5 III
U−B color index	+1.77
B−V color index	+1.52
Astrometry
Radial velocity (Rv)	+87.7 km/s
Proper motion (μ)	RA: –59.55 mas/yr ; Dec.: +188.31 mas/yr
Parallax (π)	16.84 ± 0.15 mas
Distance	194 ± 2 ly ; (59.4 ± 0.5 pc)
Absolute magnitude (MV)	−0.50
Orbit
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
Radius	107 R☉
Luminosity	392 L☉
Rotational velocity (v sin i)	3.0 km/s
Other designations
	σ Puppis, σ Pup, Sigma Pup, CPD−43 1499, FK5 1194, GC 10040, HD 59717, HIP 36377, HR 2878, SAO 218755, WDS J07292-4318A
Database references
SIMBAD	data

Sigma Puppis (Sigma Pup, σ Puppis, σ Pup) is a binary star system in the southern constellation of 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 194 light-years (59 parsecs) from Earth.^[1]

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 magnitudes, 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 measured angular diameter of the primary star is 16.71 ± 2.84 mas.^[13] At the estimated distance of this system, this yields a physical size of about 107 times the radius of the Sun.^[7] The primary component 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 Astronomical Units.^[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]

References

^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
^ ^a ^b ^c ^d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J
^ ^a ^b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, Ann Arbor: Dept. of Astronomy, University of Michigan: distributed by University Microfilms International, Bibcode:1978mcts.book.....H
^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E
^ ^a ^b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
^ ^a ^b Batten, A. H.; Fletcher, J. M.; Mann, P. J. (1978), "Seventh catalogue of the orbital elements of spectroscopic binary systems", Publications of the Dominion Astrophysical Observatory Victoria, 15: 121–295, 150–151, Bibcode:1978PDAO...15..121B
^ ^a ^b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R_*) is given by:
${\begin{aligned}2\cdot R_{*}&={\frac {(10^{{-3}}\cdot 59.4\cdot 16.71)\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{{\bigodot }}}}\\&\approx 213.5\cdot R_{{\bigodot }}\end{aligned}}$
^ Costa, J. M.; et al. (February 2002), "The tidal effects on the lithium abundance of binary systems with giant component", Astronomy and Astrophysics, 382: 1016–1020, arXiv:astro-ph/0111539, Bibcode:2002A&A...382.1016C, doi:10.1051/0004-6361:20011676
^ ^a ^b "sig Pup -- Spectroscopic binary", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2010-01-05
^ ^a ^b Plotner, Tammy; Mann, Terry (2007), The Night Sky Companion: A Yearly Guide to Sky-Watching, Patrick Moore's Practical Astronomy Series, Springer, p. 156, ISBN 0-387-71608-4, retrieved 2012-01-11
^ ^a ^b Otero, Sebastián A. (October 2007), "New Elements for 54 Eclipsing Binaries", Open European Journal on Variable Stars, 72 (1): 1–19, Bibcode:2007OEJV...72....1O
^ ^a ^b Samus, N. N.; Durlevich, O. V. (February 12, 2009), GCVS Variability Types and Distribution Statistics of Designated Variable Stars According to their Types of Variability, Sternberg Astronomical Institute, Moscow University, retrieved 2012-04-18
^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039
^ Burnham, Robert (1978), Burnham's celestial handbook: an observer's guide to the universe beyond the solar system, Dover books explaining science, 3 (2nd ed.), Courier Dover Publications, p. 150, ISBN 0-486-23673-0, retrieved 2012-01-11
^ Eggen, O. J. (June 1971), "The ζ Herculis, σ Puppis, ∈ Indi, and η Cephei Groups of Old Disk Population Stars", Publications of the Astronomical Society of the Pacific, 83 (493): 251, Bibcode:1971PASP...83..251E, doi:10.1086/129119
^ Taylor, B. J. (October 2000), "A statistical analysis of the metallicities of nine old superclusters and moving groups", Astronomy and Astrophysics, 362: 563–579, Bibcode:2000A&A...362..563T

[aaa474_2_653-1] ^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357

[clpl4_99-2] Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J

[houk1978-3] Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, Ann Arbor: Dept. of Astronomy, University of Michigan: distributed by University Microfilms International, Bibcode:1978mcts.book.....H

[rgcrv-4] Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E

[Anderson2012-5] Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.

[pdaov15_121-6] Batten, A. H.; Fletcher, J. M.; Mann, P. J. (1978), "Seventh catalogue of the orbital elements of spectroscopic binary systems", Publications of the Dominion Astrophysical Observatory Victoria, 15: 121–295, 150–151, Bibcode:1978PDAO...15..121B

[lang2006-7] Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R_*) is given by:
${\begin{aligned}2\cdot R_{*}&={\frac {(10^{{-3}}\cdot 59.4\cdot 16.71)\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{{\bigodot }}}}\\&\approx 213.5\cdot R_{{\bigodot }}\end{aligned}}$

[aaa382_1016-8] Costa, J. M.; et al. (February 2002), "The tidal effects on the lithium abundance of binary systems with giant component", Astronomy and Astrophysics, 382: 1016–1020, arXiv:astro-ph/0111539, Bibcode:2002A&A...382.1016C, doi:10.1051/0004-6361:20011676

[SIMBAD-9] "sig Pup -- Spectroscopic binary", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2010-01-05

[plotner_mann2007-10] Plotner, Tammy; Mann, Terry (2007), The Night Sky Companion: A Yearly Guide to Sky-Watching, Patrick Moore's Practical Astronomy Series, Springer, p. 156, ISBN 0-387-71608-4, retrieved 2012-01-11

[oejvs72_1_1-11] Otero, Sebastián A. (October 2007), "New Elements for 54 Eclipsing Binaries", Open European Journal on Variable Stars, 72 (1): 1–19, Bibcode:2007OEJV...72....1O

[gcvs-12] Samus, N. N.; Durlevich, O. V. (February 12, 2009), GCVS Variability Types and Distribution Statistics of Designated Variable Stars According to their Types of Variability, Sternberg Astronomical Institute, Moscow University, retrieved 2012-04-18

[aaa431_773-13] Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039

[burnham1978-14] Burnham, Robert (1978), Burnham's celestial handbook: an observer's guide to the universe beyond the solar system, Dover books explaining science, 3 (2nd ed.), Courier Dover Publications, p. 150, ISBN 0-486-23673-0, retrieved 2012-01-11

[pasp83_493_251-15] Eggen, O. J. (June 1971), "The ζ Herculis, σ Puppis, ∈ Indi, and η Cephei Groups of Old Disk Population Stars", Publications of the Astronomical Society of the Pacific, 83 (493): 251, Bibcode:1971PASP...83..251E, doi:10.1086/129119

[aaa362_563-16] Taylor, B. J. (October 2000), "A statistical analysis of the metallicities of nine old superclusters and moving groups", Astronomy and Astrophysics, 362: 563–579, Bibcode:2000A&A...362..563T

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Observation data Epoch J2000 Equinox J2000
Location of σ Puppis (circled)
Constellation	Puppis
Right ascension	07^h 29^m 13.83049^s^[1]
Declination	–43° 18′ 05.1597″^[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 (R_v)	+87.7^[4] km/s
Proper motion (μ)	RA: –59.55^[1] mas/yr Dec.: +188.31^[1] mas/yr
Parallax (π)	16.84 ± 0.15^[1] mas
Distance	194 ± 2 ly (59.4 ± 0.5 pc)
Absolute magnitude (M_V)	−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
Radius	107^[7] `R`_☉
Luminosity	392^[5] `L`_☉
Rotational velocity (v sin i)	3.0^[8] km/s

Other designations
σ Puppis, 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
SIMBAD	data