40 Cancri

40 Cancri
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Cancer
Right ascension 08h 40m 11.45263s
Declination +19° 58′ 16.0832″
Apparent magnitude (V) 6.61
Characteristics
Evolutionary stage blue straggler
Spectral type A1 V
B−V color index 0.006±0.005
Astrometry
Radial velocity (Rv)+34.4±0.6 km/s
Proper motion (μ) RA: −35.154 mas/yr
Dec.: −13.463 mas/yr
Parallax (π)5.3784±0.0417 mas
Distance606 ± 5 ly
(186 ± 1 pc)
Absolute magnitude (MV)0.32
Details
Mass2.46±0.12 M☉
Radius2.72±0.12 R☉
Luminosity91 L☉
Surface gravity (log g)3.78 cgs
Temperature9,382 K
Rotational velocity (v sin i)10 km/s
Age349 Myr
Other designations
40 Cnc, BD+20°2159, HD 73666, HIP 42523, SAO 80336, WDS J08401+2000
Database references
SIMBADdata

40 Cancri is a binary star system in the zodiac constellation of Cancer, located about 605 light years from the Sun in the Beehive Cluster (NGC 2632). It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.61. The system is moving further from the Earth with a heliocentric radial velocity of 34 km/s.

The primary component appears to be a normal A-type main-sequence star with a stellar classification of A1 V, showing neither an organized magnetic field nor a chemical peculiarity. However, it is considered an extreme blue straggler. This is a second generation star formed through a collision of two low mass stars some 5–350 million years ago. The collision was either between two separate cluster members or the coalescence of a binary star system.

With an effective temperature of 9,382 K, this is the hottest star in the cluster by about 1,200 K. It has 2.46 times the mass of the Sun and 2.72 times the Sun's radius. The star has an unusually slow rotation for an A1V star, with a projected rotational velocity of 10 km/s. It is radiating 91 times the Sun's luminosity from its photosphere.

40 Cancri has a common proper motion companion, located at an angular separation of 0.425″±0.009″ along a position angle of 127.6°±0.5°, as of 1983. This object is about 2.5±0.5 magnitudes dimmer than the primary, and is most likely an F-type star with a mass of about 1.5 M☉. The projected separation between the pair is 80 AU, so their orbital period is 450 years or greater.

References

  1. 1 2 3 4 5 6 7 8 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. 1 2 3 4 5 6 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, S2CID 119257644.
  3. 1 2 3 Andrievsky, Sergei. M. (June 1998), "Blue stragglers in open clusters. I. NGC 2632", Astronomy and Astrophysics, 334: 139−145, Bibcode:1998A&A...334..139A.
  4. 1 2 Bidelman, William P. (August 1956), "Spectral Classification of the Brighter Stars of the Praesepe Cluster", Publications of the Astronomical Society of the Pacific, 68 (403): 318, Bibcode:1956PASP...68..318B, doi:10.1086/126944.
  5. 1 2 3 4 5 6 7 8 Fossati, L.; et al. (January 2010), "Explaining the Praesepe blue straggler HD 73666", Astronomy and Astrophysics, 510: A8, arXiv:0911.1874, Bibcode:2010A&A...510A...8F, doi:10.1051/0004-6361/200811495, S2CID 118658470, A8.
  6. 1 2 3 4 5 6 Fossati, L.; et al. (December 2007), "Late stages of the evolution of A-type stars on the main sequence: comparison between observed chemical abundances and diffusion models for 8 Am stars of the Praesepe cluster", Astronomy and Astrophysics, 476 (2): 911–925, arXiv:0710.0579, Bibcode:2007A&A...476..911F, doi:10.1051/0004-6361:20078320, S2CID 16152096.
  7. ↑ "40 Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-03.