V Puppis

V Puppis

Location of V Puppis (circled)
Observation data Equinox J2000.0]] (ICRS)
Constellation	Puppis
Right ascension	07h 58m 14.43920s[1]
Declination	−49° 14′ 41.6803″[1]
Apparent magnitude (V)	4.41[2] (5.10 + 5.59)[3]
Characteristics
Spectral type	B1Vp + B3IV:[4]
U−B color index	−0.96[2]
B−V color index	−0.17[2]
Variable type	β Lyr[5]
Astrometry
Radial velocity (Rv)	+20.0±1.1[3] km/s
Proper motion (μ)	RA: −5.53±0.26[6] mas/yr Dec.: +8.27±0.25[6] mas/yr
Parallax (π)	2.40 ± 0.23[6] mas
Distance	1,400 ± 100 ly (420 ± 40 pc)
Absolute magnitude (MV)	−3.56[7]
Orbit[3]
Primary	V Pup A
Companion	V Pup B
Period (P)	1.4544859 d
Semi-major axis (a)	14.96±0.20 R☉
Eccentricity (e)	0
Inclination (i)	80.5±0.3°
Semi-amplitude (K1) (primary)	175.4±3.2 km/s
Semi-amplitude (K2) (secondary)	338.8±5.4 km/s
Orbit[6]
Primary	V Pup AB
Companion	V Pup C
Period (P)	14.0344±0.0026 yr
Semi-major axis (a)	17.88±0.15 au
Eccentricity (e)	0.4587±0.0046
Inclination (i)	87.9±3.3°
Longitude of the node (Ω)	4.6+5.7 −3.3°
Periastron epoch (T)	2,460,860.6±6.4 JD
Argument of periastron (ω) (secondary)	202.55±0.46°
Semi-amplitude (K1) (primary)	11.353+0.073 −0.071 km/s
Details[3]
V Pup A
Mass	14.0±0.5 M☉
Radius	5.48±0.18 R☉
Luminosity	12,600±2,100 L☉
Temperature	26,000±1,000 K
Rotational velocity (v sin i)	246±5 km/s
Age	5.0±0.8 Myr
V Pup B
Mass	7.3±0.3 M☉
Radius	4.59±0.15 R☉
Luminosity	6,500+1,300 −1,100 L☉
Temperature	24,000±1,000 K
Rotational velocity (v sin i)	209±6 km/s
Age	5.0±0.8 Myr
V Pup C
Mass	7.73±0.14[6] M☉
Other designations
CD−48°3349, CCDM J07582-4915A, GC 10802, GSC 08143−03239, HIP 38957, HR 3129, HD 65818, SAO 219226, WDS J07582-4915A
Database references
SIMBAD	data

V Puppis (V Pup) is a star system in the constellation Puppis. It has an apparent magnitude of 4.41, which is bright enough to be seen with the naked eye. Based on parallax measurements, it lies at a distance of 420 parsecs (1,400 light-years).

This is a massive eclipsing binary with an orbital period of only 1.4544859 days. The two stars are separated by 15 solar radii (0.070 astronomical unit|au; 10,000,000 km), being on a semi-detached configuration.^[3] The primary, V Puppis A, is of spectral type B1Vp,^[4] has 14 times the mass of the Sun and 5.5 times the Sun's radius. It radiates 12,600 times the solar luminosity from its photosphere at an effective temperature of 26,000 K.^[3] The secondary, V Puppis B, is of spectral type B3IV:,^[4] has 7.3 times the Sun's mass and 4.6 times the radius. It radiates 6,500 times the Sun's luminosity from its photosphere at an effective temperature of 24,000 K.^[3]

While the primary's properties are consistent with a main sequence evolution, the secondary appears overluminous compared to a main sequence star of same mass. It is thought that the secondary was formerly the most massive component but underwent mass transfer with the former secondary – most of the mass got ejected into space rather than being accreted to the former secondary.^[3]

This system makes part of the multiple star system WDS J07582-4915, which consists on the visual components:^[9]

• WDS J07582-4915 A, V Puppis
• B, a magnitude 11.5 star separated 6.2" from A;
• C, at magnitude 13.2 and separation 18.9";
• D, at magnitude 9.88 and separation 39";
• E, at magnitude 13 and separation from D of 10.4".

At least D appears to be a physical companion to V Puppis.^[3] It is 403 ± 2 parsecs (1,314.4 ± 6.5 light-years) away based on its Gaia DR3 parallax^[10] and is a 96% probability member of the OCSN 199 cluster.^[11] Component B is 406.9 ± 3.5 parsecs (1,327 ± 11 light-years) away^[12] and is a member of the OCSN 200 cluster with 96% probability.^[11] Component C is 324 ± 15 parsecs (1,057 ± 49 light-years) away and shares a common proper motion with V Puppis,^[13] while component E is a background object unrelated to all other companions, 2,460 ± 60 parsecs (8,020 ± 200 light-years) away.^[14]

The observed times for the V Puppis eclipses differ from the predicted times, suggesting that it has an outer companion whose light travel time effect causes such deviations. The third body was initially calculated in 2008 to have an orbital period of 5.47 years and a mass of 10.4 solar masses. Based on the mass of the object, its lack of a visible spectrum, and circumstellar matter in the system with many heavy elements (as would be produced by a past supernova in the system), it was thought to be probably a black hole.^[15]

A follow-up study could not confirm this object, but found signs that there may be a third object which is fainter than the other components, which would be a mid to late-type B-type star.^[3]

A 2025 study combining all previous eclipse data and astrometry from the Hipparcos and Gaia spacecrafts again suggested the presence of a black hole. The period and mass were revised to 14.034 years and 7.73 M_☉. Additional data is still necessary to confirm the nature of this object as either a black hole or a B-type main-sequence star that was not direcly detected yet.^[6]

If this companion is confirmed as a black hole, it would be among the closest-known, with a similar distance to the current leader, Gaia BH1.

• Andersen, J.; Clausen, J. V.; Gimenez, A.; Nordstroem, B. (December 1983). "Absolute dimensions of eclipsing binaries. II. The early-type semidetached system V Puppis." (in en). Astronomy and Astrophysics 128: 17–28. ISSN 0004-6361. Bibcode: 1983A&A...128...17A. 
• Stickland, D. J.; Lloyd, C.; Pachoulakis, I.; Koch, R. H. (December 1998). "Spectroscopic binary orbits from ultraviolet radial velocities. Paper 29: V Puppis (HD 65818)" (in en). The Observatory 118: 356–364. ISSN 0029-7704. Bibcode: 1998Obs...118..356S. 

Coordinates: 07^h 58^m 14.43920^s, −49° 14′ 41.6803″

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