Kruger 60

Binary star system in the constellation Cepheus

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Krüger 60 A/B

A blue band light curve for a flare on DO Cephei, adapted from Dal (2020)[1]

Observation data
Epoch J2000 Equinox
Constellation | Cepheus
Krüger 60 A
Right ascension | 22h 27m 59.55755s[2]
Declination | +57° 41′ 42.0806″[2]
Apparent magnitude (V) | 9.59[citation needed]
Krüger 60 B
Right ascension | 22h 27m 59.79560s[3]
Declination | +57° 41′ 49.7468″[3]
Apparent magnitude (V) | 11.40[citation needed]
Characteristics
Spectral type | M3V/M4V[4]
U−B color index | 1.27/1.3[citation needed]
B−V color index | 1.65/1.8[citation needed]
Variable type | None/Flare star
Astrometry
Krüger 60 A
Radial velocity (Rv)| –33.1[citation needed] km/s
Proper motion (μ)|  RA: −725.227±0.537[2] mas/yr
Dec.: −223.461±0.348[2] mas/yr
Parallax (π)| 249.3926 ± 0.1653 mas[2]
Distance| 13.078 ± 0.009 ly
(4.010 ± 0.003 pc)
Absolute magnitude (MV)| 11.76
Krüger 60 B
Radial velocity (Rv)| –31.9[citation needed] km/s
Proper motion (μ)|  RA: −934.098±1.319[3] mas/yr
Dec.: −686.244±1.410[3] mas/yr
Parallax (π)| 249.9668 ± 0.7414 mas[3]
Distance| 13.05 ± 0.04 ly
(4.00 ± 0.01 pc)
Absolute magnitude (MV)| 13.46
Details
Krüger 60 A
Mass| 0.271[5] M☉
Radius| 0.35[6] R☉
Luminosity| 0.010[citation needed] L☉
Temperature| 3,180[citation needed] K
Metallicity| –0.04[7]
Krüger 60 B
Mass| 0.176[5] M☉
Radius| 0.24[6] R☉
Luminosity| 0.0034[citation needed] L☉
Temperature| 2,890[citation needed] K
Orbit[8]
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[9]

Database references
SIMBAD| The system
| A
| B

Krüger 60

Location 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[edit]

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.[5][6] Component B is a flare star and has been given the variable star designation "DO Cephei".[10] It is an irregular flare that typically doubles in brightness and then returns to normal over an 8-minute period.[citation needed]

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.[citation needed]

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.[11] The closest approach to the Sun will occur in about 88,600 years when this system will come within 1.95 parsecs.[12]

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[edit]

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.[13] 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.[13]

## See also[edit]

* List of nearest stars and brown dwarfs

## References[edit]

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. Retrieved 6 December 2021.
2. ^ a b c d e 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. ^ a b c d e 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. ^ a b c 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. ^ a b c 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. ^ a b 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 [astro-ph.EP].

## Further reading[edit]

* 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[edit]

* Hires LRGB CCD Image

* v
* t
* e

← Celestial objects within 10–15 light-years →

| Primary member type|

Celestial objects by systems.

| Subgiant stars|

| F-type|

* Procyon (Alpha Canis Minoris) (11.402±0.032 ly)
* white dwarf B

|

| Main-sequence
stars|

| G-type|

* Tau Ceti (11.9118±0.0074 ly)
* 4 (8?) planets: (b), (c), (d), e, f, g, h, (i)

|

K-type|

* Epsilon Eridani (Ran) (10.4749±0.0037 ly)
* 1 (2?) planets: b (Ægir), c?
* 61 Cygni (11.4039±0.0012 ly)
* K-type main-sequence star B
* Epsilon Indi (11.8670±0.0041 ly)
* 2 T-type brown dwarfs: Ba, Bb
* planet Ab

M-type
(red dwarfs)|

* Ross 248 (10.3057±0.0014 ly)
* Lacaille 9352 (10.7241±0.0007 ly)
* 2 (3?) planets: b, c, d?
* Ross 128 (11.0074±0.0011 ly)
* planet b
* EZ Aquarii (11.109±0.034 ly)
* 2 red dwarfs: B, C
* Struve 2398 (11.4908±0.0009 ly)
* red dwarf B
* 2 planets: Bb, Bc
* Groombridge 34 (11.6191±0.0008 ly)
* red dwarf B
* 2 planets: Ab, Ac
* DX Cancri (11.6797±0.0027 ly)
* Gliese 1061 (11.9839±0.0014 ly)
* 3 planets: b, c, d
* YZ Ceti (12.1222±0.0015 ly)
* 3 (4?) planets: b, c, d, e?
* Luyten's Star (12.3485±0.0019 ly)
* 4 planets: b, c, d, e
* Teegarden's Star (12.4970±0.0045 ly)
* 2 planets: b, c
* Kapteyn's Star (12.8308±0.0008 ly)
* 2 planets: b, c
* Lacaille 8760 (12.9472±0.0018 ly)
* SCR 1845-6357 (13.0638±0.0070 ly)
* T-type brown dwarf B
* Kruger 60 (13.0724±0.0052 ly)
* red dwarf B
* DEN 1048−3956 (13.1932±0.0027 ly)
* Ross 614 (13.363±0.040 ly)
* red dwarf B
* Wolf 1061 (14.0500±0.0016 ly)
* 3 planets: b, c, d
* Gliese 1 (14.1747±0.0022 ly)
* TZ Arietis (14.5780±0.0046 ly)
* Wolf 424 (14.595±0.031 ly)
* red dwarf B
* Gliese 687 (14.8395±0.0014 ly)
* planet b
* Gliese 674 (14.8492±0.0018 ly)
* planet b
* LHS 292 (14.8706±0.0041 ly)

| Degenerate
stars|

| White dwarfs|

* van Maanen 2 (14.0718±0.0011 ly)

|

| Brown dwarfs|

| T-type|

* UGPS J0722-0540 (13.43±0.13 ly)

|

* 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
* ρ1
* ρ2

|

Flamsteed|

* 7
* 9
* 11
* 14
* 16
* 19
* 24
* 2 UMi

Variable|

* T
* V
* W
* RW
* VV
* VW
* WZ
* DH
* DO
* MY
* PV
* V354
* V381
* V419

HR|

* 597
* 7955
* 8281
* 8442
* 8702
* 8748
* 8938
* 9038

HD|

* 1
* 204521

Other|

* Gliese 809
* WISE 0313+7807
* WR 156

| Exoplanets|

* γ Cephei Ab (Tadmor)

|

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|

* Barnard 150
* Elephant's Trunk Nebula
* Ghost 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

Category
*[RA:]: Right Ascension
*[Dec.:]: Declination
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template
*[Primary]: Primary member of a system is the brightest one (and, in most cases, also the most massive one).