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.
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 15–20 light-years

| Primary member type|

Celestial objects by systems.

| Subgiant stars|

| G-type|

* Delta Pavonis (19.893±0.015 ly)

|

| Main-sequence
stars|

| A-type|

* Altair (Alpha Aquilae) (16.730±0.049 ly)

|

G-type|

* Alsafi (Sigma Draconis) (18.7993±0.0081 ly)
* Achird (Eta Cassiopeiae) (19.3314±0.0025 ly)
* K-type main-sequence star B
* e (82 G.) Eridani (19.7045±0.0093 ly)
* 3 (6?) planets: b, c?, d (c), e?, f?, g?, d

K-type|

* Groombridge 1618 (15.8857±0.0017 ly)
* Omicron2 (40) Eridani (16.3330±0.0042 ly)
* white dwarf B
* red dwarf C
* 70 Ophiuchi (16.7074±0.0087 ly)
* K-type main-sequence star B
* Gliese 570 (19.1987±0.0074 ly)
* 2 red dwarfs: B, C
* T-type brown dwarf D
* 36 Ophiuchi (19.4185±0.0036 ly)
* 2 K-type main-sequence stars: B, C
* HR 7703 (19.609±0.013 ly)
* red dwarf B

M-type
(red dwarfs)|

* GJ 1245 (15.2001±0.0034 ly)
* 2 red dwarfs: B, C
* Gliese 876 (15.2382±0.0025 ly)
* 4 planets: d, c, b, e
* LHS 288 (15.7586±0.0034 ly)
* GJ 1002 (15.8060±0.0036 ly)
* 2 planets: b, c
* Gliese 412 (15.9969±0.0026 ly)
* red dwarf B
* AD Leonis (16.1939±0.0024 ly)
* Gliese 832 (16.2005±0.0019 ly)
* planet b
* Gliese 682 (16.3328±0.0026 ly)
* 2? planets: b?, c?
* EV Lacertae (16.4761±0.0018 ly)
* G 9-38 (16.800±0.011 ly)
* red dwarf B
* GJ 3379 (16.9861±0.0027 ly)
* Gliese 445 (17.1368±0.0017 ly)
* 2M1540 (17.3738±0.0046 ly)
* GJ 3323 (17.5309±0.0026 ly)
* 2 planets: b, c
* Gliese 526 (17.7263±0.0024 ly)
* Stein 2051 (17.9925±0.0020 ly)
* white dwarf B
* Gliese 251 (18.2146±0.0028 ly)
* planet b
* LP 816-60 (18.3305±0.0038 ly)
* LSR J1835+3259 (18.5534±0.0049 ly)
* Gliese 205 (18.6042±0.0022 ly)
* Gliese 229 (18.7906±0.0018 ly)
* T-type brown dwarf B
* 2 planets: Ab, Ac
* Ross 47 (18.8883±0.0031 ly)
* Gliese 693 (19.2078±0.0053 ly)
* Gliese 754 (19.2724±0.0067 ly)
* Gliese 908 (19.2745±0.0032 ly)
* Gliese 752 (19.2922±0.0027 ly)
* red dwarf B (vB 10)
* planet Ab
* Gliese 588 (19.2996±0.0031 ly)
* 2? planets: b?, c?
* YZ Canis Minoris (19.5330±0.0040 ly)
* GJ 1005 (19.577±0.035 ly)
* red dwarf B
* Gliese 268 (19.7414±0.0076 ly)
* red dwarf B

| Degenerate
stars|

| White dwarfs|

* Gliese 440 (15.1226±0.0013 ly)

|

| Brown dwarfs|

| L-type|

* DENIS 0255−4700 (15.877±0.014 ly)

|

T-type|

* WISE 1741+2553 (15.22±0.20 ly)
* WISE 1506+7027 (16.856±0.052 ly)
* DENIS 0817-6155 (17.002±0.037 ly)
* 2MASS 0939-2448 (17.41±0.44 ly)
* T-type brown dwarf B
* 2MASS 1114-2618 (18.20±0.14 ly)
* 2MASS 0415-0935 (18.62±0.18 ly)
* SIMP0136 (19.955±0.057 ly)
* 2MASS 0937+2931 (19.96+0.22
−0.21 ly)

Y-type|

* WISE 1639−6847 (15.450±0.041 ly)
* WISE 0350−5658 (18.49±0.24 ly)

| Sub-brown dwarfs
and rogue planets|

| Y-type|

* WISE 1541−2250 (19.54±0.24 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|

* 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
*[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).