KQ Puppis

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KQ Puppis
Wide-field view of the bright star clusters Messier 47 and Messier 46 (eso1441c).jpg
KQ Puppis is the bright red star on the right, with Messier 47 to its left (east) and Messier 46 even further east.
Observation data
Epoch J2000       Equinox J2000
Constellation Puppis
Right ascension 07h 33m 47.96383s [1]
Declination −14° 31′ 26.0026″ [1]
Apparent magnitude  (V)+4.97 [2] (4.82 - 5.17 [3] )
Characteristics
KQ Pup A
Evolutionary stage Red supergiant [4]
Spectral type M2Iab [5]
U−B color index +0.29 [2]
B−V color index +1.41 [2]
Variable type Slow irregular variable [3]
KQ Pup B
Evolutionary stage Main sequence [4]
Spectral type B2V + (A/F)V [4]
Astrometry
Radial velocity (Rv)+34.4 [4] km/s
Proper motion (μ)RA: -7 [6] mas/yr
Dec.: +4 [6] mas/yr
Parallax (π)1.29±0.10  mas [4]
Distance 2,500 ± 200  ly
(780 ± 60  pc)
Orbit [4]
PrimaryKQ Pup Ba
CompanionKQ Pup Bb
Period (P)17.2596 days
Semi-major axis (a)0.3 au
Eccentricity (e)≥0.236
Inclination (i)~90°
Orbit [4]
PrimaryKQ Pup A
CompanionKQ Pup B
Period (P)9,500 days
Semi-major axis (a)24.89±1.48  au
Eccentricity (e)0.62±0.01
Inclination (i)70.3±1.2°
Longitude of the node (Ω)319.3±3.6°
Periastron epoch (T)60,310  MJD
Argument of periastron (ω)
(primary)		203.5±2.2°
Semi-amplitude (K1)
(primary)		17.1 km/s
Details [4]
KQ Pup A
Mass 9.12+1.73
−1.53  M☉
Radius 491+41
−36  R☉
Luminosity 38,000+7,700
−4,900  L☉
Temperature 3,660±170  K
Age 18.7–46.9  Myr
KQ Pup Ba
Mass 7.5–11.5  M☉
Luminosity 8,900  L☉
Temperature 19,900  K
Rotational velocity (v sin i)190±70 km/s
Age 18.7–46.9  Myr
KQ Pup Bb
Mass 4.4+3.7
−3.2  M☉
Age 18.7–46.9  Myr
Other designations
KQ Pup, BD −14°1971, HIP  36773, HR  2902, NGC  2422 9, SAO  153072
KQ Pup A: HD  60414
KQ Pup B: HD  60415
Database references
SIMBAD data

KQ Puppis is a triple star [4] system in the constellation of Puppis. With an apparent magnitude varying between 4.82 and 5.17, it is faintly visible to the naked eye under skies with little to no luminous pollution. Based on dynamical parallax measurements, it is located at a distance of 2,500 light-years (770 parsecs ).

Characteristics

A light curve for KQ Puppis, plotted from Hipparcos data KQPupLightCurve.png
A light curve for KQ Puppis, plotted from Hipparcos data

The KQ Puppis system consists of three stars in a hierarchical configuration (i.e. a compact binary around a third component). The primary component, KQ Puppis A, is a red supergiant with around nine times the mass of the Sun, and 490 times the Sun's radius. It radiates 38,000 times the Sun's luminosity from its photosphere at an effective temperature of 3,660  K. [4] It shows small amplitude irregular pulsations, and also some variation associated with the orbital motion. [8]

KQ Puppis B is an eclipsing binary with an orbital period of 17.26 days and an estimated semi-major axis of 0.3  astronomical units. This inner pair orbits the red supergiant with an orbital period of 9,500 days and a semi-major axis of 24.9 au. KQ Puppis Ba is a rapidly-rotating B-type main-sequence star, with a mass between 7.5 and 11.5 times that of the Sun, a luminosity 8,900 times solar and a temperature around 19,900 K. KQ Puppis Bb has a mass in the range of 1.2–8.1  M☉ and is thought to be either an A or F-type main-sequence star. The eccentricity of the inner orbit (≥0.236) is much higher than the expected for such a compact system, suggesting that the stellar wind of the supergiant is exciting the pair's eccentricity. No evidence of past mass transfer between the components has been found. [4]

The red supergiant is losing mass from its strong stellar wind. Some of this mass is being transferred to the secondary (B), forming a disk of material around it. [4] Binaries with such a characteristic are referred to as VV Cephei systems, although in this case the components do not eclipse each other. [9] A portion of the disc does appear to be eclipsed and this is detected as a strong drop in far-ultraviolet radiation for about a third of the orbit. [5]

KQ Puppis has been catalogued as an outlying member of the open cluster Messier 47 (NGC 2422) and would be the brightest member of that cluster. [10] Membership is uncertain as it appears to be more distant than the other stars in the cluster. [11]

References

  1. 1 2 Van Leeuwen, F. (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. S2CID   18759600.
  2. 1 2 3 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. 1 2 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: 02025. Bibcode:2009yCat....102025S.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 Jadlovský, D.; Molnár, L.; Ercolino, A.; Bernini-Peron, M.; Mérand, A.; Krtička, J.; Wang, L.; Ádám, R. Z.; Baade, D. (2025-09-29). "Hidden massive eclipsing binaries in red supergiant systems: The hierarchical triple system KQ Puppis and other candidates". arXiv: 2509.25168 [astro-ph.SR].
  5. 1 2 González-Riestra, R.; Rossi, C.; Viotti, R. F. (2003). "First far-UV observations of KQ Puppis with FUSE". Astronomy and Astrophysics. 399 (2): 681. Bibcode:2003A&A...399..681G. doi: 10.1051/0004-6361:20021830 .
  6. 1 2 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.
  7. ↑ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
  8. ↑ Viotti, R.; Rossi, C.; Muratorio, G. (1998). "Optical and near-IR observations of variable stars with AURELIE". Astronomy and Astrophysics Supplement. 128 (3): 447. Bibcode:1998A&AS..128..447V. doi: 10.1051/aas:1998156 .
  9. ↑ Rossi, C.; Altamore, A.; Baratta, G. B.; Friedjung, M.; Viotti, R. (1992). "The spectrum of the VV Cephei star KQ Puppis (Boss 1985). III - A possible model". Astronomy and Astrophysics. 256: 133. Bibcode:1992A&A...256..133R.
  10. ↑ Van Schewick, H. (1966). "Untersuchungen uber die Eigenbewegungen von Sternhaufen. XII. NGC 2422, NGC 2423, NGC 7209 und An. Bakhatova I im Sel. Area 40". Veroeff. Univ. Sternw. Bonn. 74: 1. Bibcode:1966VeBon..74....1V.
  11. ↑ Baumgardt, H.; Dettbarn, C.; Wielen, R. (2000). "Absolute proper motions of open clusters. I. Observational data". Astronomy and Astrophysics Supplement. 146 (2): 251. arXiv: astro-ph/0010306 . Bibcode:2000A&AS..146..251B. doi:10.1051/aas:2000362. S2CID   7180188.
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