Kruger 60
Kruger 60 (DO Cephei) is a binary star system located 13.15 light-years from the Sun. These red dwarf stars orbit each other every 44.6 years.
| Observation data Epoch J2000 Equinox | |
|---|---|
| Constellation | Cepheus |
| Kruger 60 A | |
| Right ascension | 22h 27m 59.4677s[1] |
| Declination | +57° 41′ 45.150″[1] |
| Apparent magnitude (V) | 9.59 |
| Kruger 60 B | |
| Right ascension | 22h 27m 59.568s[1] |
| Declination | +57° 41′ 45.28″[1] |
| Apparent magnitude (V) | 11.40 |
| Characteristics | |
| Spectral type | M3V/M4V[2] |
| U−B color index | 1.27/1.3 |
| B−V color index | 1.65/1.8 |
| Variable type | None/Flare star |
| Astrometry | |
| Radial velocity (Rv) | –33.1/–31.9 km/s |
| Proper motion (μ) | RA: –870.23 mas/yr Dec.: –471.10 mas/yr |
| Parallax (π) | 247.5 ± 1.5[3] mas |
| Distance | 13.18 ± 0.08 ly (4.04 ± 0.02 pc) |
| Absolute magnitude (MV) | 11.76/13.46 |
| Details | |
| Krueger 60 A | |
| Mass | 0.271[4] M☉ |
| Radius | 0.35[5] R☉ |
| Luminosity | 0.010 L☉ |
| Temperature | 3,180 K |
| Metallicity | –0.04[6] |
| Krueger 60 B | |
| Mass | 0.176[4] M☉ |
| Radius | 0.24[5] R☉ |
| Luminosity | 0.0034 L☉ |
| Temperature | 2,890 K |
| Orbit[7] | |
| Primary | Kruger 60 A |
| Companion | Kruger 60 B |
| Period (P) | 44.67 yr |
| Semi-major axis (a) | 2.383″ |
| Eccentricity (e) | 0.410 |
| Inclination (i) | 167.2° |
| Longitude of the node (Ω) | 154.5° |
| Periastron epoch (T) | 1970.22 |
| Argument of periastron (ω) (primary) | 211.0° |
| Other designations | |
| Database references | |
| SIMBAD | The system |
| A | |
| B | |
Description
The larger, primary star is designated component A, while the secondary, smaller star is labeled component B. Component A has about 27% of the Sun's mass and 35% of the Sun's radius. Component B has about 18% of the Sun's mass and 24% of the Sun's radius.[4][5] Component B is a flare star and has been given the variable star designation "DO Cephei".[9] It is an irregular flare that typically doubles in brightness and then returns to normal over an 8-minute period.
On average, the two stars are separated by 9.5 AUs, which is roughly the average distance of Saturn from the Sun. However, their eccentric mutual orbit causes their distance to vary between 5.5 AUs at periastron, to 13.5 at apastron.
This system is orbiting through the Milky Way at a distance from the core that varies from 7–9 kpc with an orbital eccentricity of 0.126–0.130.[10] The closest approach to the Sun will occur in about 88,600 years when this system will come within 1.95 parsecs.[11]
Considering the orbit of the members of Kruger 60, detecting an exoplanet through radial velocity could prove difficult, as its orbit would be inclined only 13 degrees from our point of view, and create 1/5th as strong a radial velocity signal as an exoplanet orbiting edge-on from the point of view of the Solar System.
Origin of 2I/Borisov
Kruger 60 has been proposed as the origin of interstellar comet 2I/Borisov (formerly named C/2019 Q4 (Borisov)) by Dybczyński, Królikowska, and Wysoczańska.[12] These authors have from other work a list of stars and stellar systems that can potentially act as perturbers of the Oort cloud comets, and searched it for a past close proximity of 2I/Borisov at a very small relative velocity. While hampered by continuing uncertainty about the orbit of 2I/Borisov and particularly its non-gravitational acceleration (due to cometary outgassing), they reach a conclusion that 1 Myr ago 2I/Borisov passed Kruger 60 at a small distance of 1.74 pc while having an extremely small relative velocity of 3.43 km/s. Perturbations of the 2I/Borisov's incoming orbit altered the intersection distance with relatively small changes in the relative velocity. At the time of publication, the results were considered preliminary as the orbit of 2I/Borisov was still being improved by new observations.
References
- Perryman, M. A. C.; Lindegren; Kovalevsky; Hoeg; Bastian; Bernacca; Crézé; Donati; Grenon; et al. (1997). "The Hipparcos Catalogue". Astronomy and Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P.
- Henry, Todd J.; et al. (October 1994). "The solar neighborhood, 1: Standard spectral types (K5-M8) for northern dwarfs within eight parsecs". The Astronomical Journal. 108 (4): 1437–1444. Bibcode:1994AJ....108.1437H. doi:10.1086/117167.
- Söderhjelm, Staffan (1999). "HIP 110893". Visual binary orbits and masses post Hipparcos. Retrieved 2014-10-21.
- Delfosse, X.; Forveille; Ségransan; Beuzit; Udry; Perrier; Mayor (December 2000). "Accurate masses of very low mass stars. IV. Improved mass-luminosity relations". Astronomy and Astrophysics. 364: 217–224. arXiv:astro-ph/0010586. Bibcode:2000A&A...364..217D.
- Pasinetti Fracassini, L. E.; et al. (February 2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy and Astrophysics. 367 (2): 521–524. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. S2CID 425754. The data is from the Vizier II/224 catalogue.
- Bonfils, X.; et al. (November 2005). "Metallicity of M dwarfs. I. A photometric calibration and the impact on the mass-luminosity relation at the bottom of the main sequence". Astronomy and Astrophysics. 442 (2): 635–642. arXiv:astro-ph/0503260. Bibcode:2005A&A...442..635B. doi:10.1051/0004-6361:20053046. S2CID 13900901. Only listed for component A.
- Heintz, W. D. (August 1986). "Orbits of 20 visual binaries". Astronomy and Astrophysics Supplement Series. 65 (2): 411–417. Bibcode:1986A&AS...65..411H.
- "NSV 14168 – Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-09-28.
- White, Stephen M.; et al. (December 1989). "A VLA survey of nearby flare stars". Astrophysical Journal Supplement Series. 71: 895–904. Bibcode:1989ApJS...71..895W. doi:10.1086/191401.
- Allen, C.; Herrera, M. A. (1998). "The galactic orbits of nearby UV Ceti stars". Revista Mexicana de Astronomía y Astrofísica. 34: 37–46. Bibcode:1998larm.confE.115A.
- García-Sánchez, J.; et al. (November 2001). "Stellar encounters with the solar system". Astronomy and Astrophysics. 379 (2): 634–659. Bibcode:2001A&A...379..634G. doi:10.1051/0004-6361:20011330.
- Dybczyński, Piotr A.; Królikowska, Małgorzata; Wysoczańska, Rita (24 September 2019). "Kruger 60 – a plausible home system of the interstellar comet C/2019 Q4". arXiv:1909.10952 [astro-ph.EP].
Further reading
- James B. Kaler (22 March 2001). Extreme Stars: At the Edge of Creation. Cambridge University Press. p. 31. ISBN 978-0-521-40262-0.
