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Krüger 60 A/B

A blue band light curve for a flare on DO Cephei, adapted from Dal (2020)
Observation data Epoch J2000      Equinox
Constellation	Cepheus
Krüger 60 A
Right ascension	22 27 59.55755
Declination	+57° 41′ 42.0806″
Apparent magnitude (V)	9.59
Krüger 60 B
Right ascension	22 27 59.79560
Declination	+57° 41′ 49.7468″
Apparent magnitude (V)	11.40
Characteristics
Spectral type	M3V/M4V
U−B color index	1.27/1.3
B−V color index	1.65/1.8
Variable type	None/Flare star
Astrometry
Krüger 60 A
Radial velocity (Rv)	–33.1 km/s
Proper motion (μ)	RA: −725.227±0.537 mas/yr Dec.: −223.461±0.348 mas/yr
Parallax (π)	249.3926 ± 0.1653 mas
Distance	13.078 ± 0.009 ly (4.010 ± 0.003 pc)
Absolute magnitude (MV)	11.76
Krüger 60 B
Radial velocity (Rv)	–31.9 km/s
Proper motion (μ)	RA: −934.098±1.319 mas/yr Dec.: −686.244±1.410 mas/yr
Parallax (π)	249.9668 ± 0.7414 mas
Distance	13.05 ± 0.04 ly (4.00 ± 0.01 pc)
Absolute magnitude (MV)	13.46
Details
Krüger 60 A
Mass	0.271 M☉
Radius	0.35 R☉
Luminosity	0.010 L☉
Temperature	3,180 K
Metallicity	–0.04
Krüger 60 B
Mass	0.176 M☉
Radius	0.24 R☉
Luminosity	0.0034 L☉
Temperature	2,890 K
Orbit
Primary	Krüger 60 A
Companion	Krüger 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
BD+56° 2783, GJ 860 A/B, HD 239960, HIP 110893, ADS 15972, G 232-075, LHS 3814/3815
Database references
SIMBAD	The system
	A
	B
Krüger 60Location of Krüger 60 in the constellation Cepheus

Krüger 60 (DO Cephei) is a binary star system located 13.1 light-years (4.0 parsecs) from the Sun. These red dwarf stars orbit each other every 44.6 years.

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. Component B is a flare star and has been given the variable star designation "DO Cephei". 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. The closest approach to the Sun will occur in about 88,600 years when this system will come within 1.95 parsecs.

Considering the orbit of the members of Krüger 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

Krüger 60 was proposed as the origin of interstellar comet 2I/Borisov (formerly named C/2019 Q4 (Borisov)) in a preprint submitted to arXiv by Dybczyński, Królikowska, and Wysoczańska. These authors had 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 uncertainty about the orbit of 2I/Borisov and particularly its non-gravitational acceleration (due to cometary outgassing), they initially reached a conclusion that 1 Myr ago 2I/Borisov passed Krüger 60 at a small distance of 1.74 pc while having an extremely small relative velocity of 3.43 km/s. Perturbations of 2I/Borisov's incoming orbit altered the intersection distance with relatively small changes in the relative velocity. However, further study by the same authors presented in the revised version of the preprint instead ruled out the possibility of Krüger 60 as a home system for 2I/Borisov.

See also

• List of nearest stars and brown dwarfs

References

1. Dal, H. A. (July 2020). "The flare cumulative frequencies of UV Ceti stars from different spectral types". Monthly Notices of the Royal Astronomical Society. 495 (4): 4529–4541. Bibcode:2020MNRAS.495.4529D. doi:10.1093/mnras/staa1484.
2. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
3. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
4. 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.
5. ^ Delfosse, Xavier; et al. (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
6. ^ 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.
7. Bonfils, Xavier; Delfosse, Xavier; Udry, Stéphane; Santos, Nuno C.; Forveille, Thierry; Ségransan, Damien (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.
8. Heintz, W. D. (August 1986). "Orbits of 20 visual binaries". Astronomy and Astrophysics Supplement Series. 65 (2): 411–417. Bibcode:1986A&AS...65..411H.
9. "NSV 14168 – Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-09-28.
10. 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.
11. 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.
12. 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.
13. ^ Dybczyński, Piotr A.; Królikowska, Małgorzata; Wysoczańska, Rita (24 September 2019). "Kruger 60 as a home system for 2I/Borisov -- a case study". arXiv:1909.10952 .

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.

External links

• Hires LRGB CCD Image

v t e Constellation of Cepheus
List of stars in Cepheus Cepheus in Chinese astronomy
Stars	Bayer α (Alderamin) β (Alfirk) γ (Errai) δ ε ζ η θ ι κ λ μ (Garnet Star) ν ξ (Kurhah) ο π ρ ρ Flamsteed 7 9 11 14 16 19 24 2 UMi Variable AR T V W RW VV VW WZ DH DO MY PV S SS ST U V354 V381 V419 HR 597 881 7955 8281 8442 8702 8748 8938 9038 HD 1 197911 204521 Other Gliese 809 WISE 0313+7807 WR 156 IRAS 23077+6707
Exoplanets γ Cephei Ab (Tadmor) TOI-1431 b
Star clusters	NGC 188 6939 7023 7129 7142 7160 7380 7419 7429 7510 Other Palomar 1
Nebulae	NGC NGC 40 NGC 7129 NGC 7139 NGC 7354 NGC 7538 NGC 7822 Other Seahorse Nebula Elephant's Trunk Nebula Ghost Nebula Gyulbudaghian's Nebula IC 1396 Iris Nebula L1157 S 155 SSTGFLS J222557+601148
Galaxies	NGC 2276 2300 6952 Other 3C 61.1 S5 0014+81 NVSS 2146+82 UGC 11861
Category

• Cepheus (constellation)
• Local Bubble
• M-type main-sequence stars
• Flare stars
• Binary stars
• Henry Draper Catalogue objects
• Hipparcos objects
• Gliese and GJ objects
• Durchmusterung objects
• Objects with variable star designations