Krüger 60 (DO Cephei) is a
binary star
A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...
system located from Earth, being
one of nearest stars. It is made up of a pair of
red dwarf
A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...
s stars orbiting each other every 45 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
The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies a ...
and 30% of the
Sun's radius
Solar radius is a unit of distance used to express the size of objects in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3:
1\,R_ = 6.957\ti ...
. Component B has about 18% of the Sun's mass and 21% of the Sun's radius.
[
In 1951, Peter van de Kamp and Sarah Lee Lippincott announced that component B is a ]flare star
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to magnetic reconnection, the magne ...
.variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...
designation "DO Cephei".[ Flares lasting as long as one hour have been recorded.][
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 .][
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.
]
Name
In 1890 Adalbert Krueger
Karl Nikolaus Adalbert Krueger (9 December 1832 – 21 April 1896) was a German astronomer. Born in Marienburg, Prussia (now Malbork, Poland), he was editor of ''Astronomische Nachrichten ''from 1881 until his death.
Krueger died of a heart cond ...
published a part of the AGK catalogue with stars with declination
In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or ...
between +55 en +65. He noted which stars appeared to be double. Sherburne Wesley Burnham
Sherburne Wesley Burnham (December 12, 1838 – March 11, 1921) was an American astronomer.
For more than 50 years Burnham spent all his free time observing the heavens, mainly concerning himself with binary stars.
Biography
Sherburne ...
(1894) observed 67 of these candidate double stars, among which number 60 from his list, which later was called Kruger 60 (star 13170 from the catalogue of Krueger).[https://articles.adsabs.harvard.edu/full/1894PLicO...2..145B]
Origin of 2I/Borisov
Krüger 60 was proposed as the origin of interstellar comet 2I/Borisov
2I/Borisov, originally designated C/2019 Q4 (Borisov), is the first observed rogue comet and the second observed interstellar interloper after ʻOumuamua. It was discovered by the Crimean Amateur astronomy, amateur astronomer and telescope make ...
(formerly named C/2019 Q4 (Borisov)) in a preprint
In academic publishing, a preprint is a version of a scholarly or scientific paper that precedes formal peer review and publication in a peer-reviewed scholarly or scientific journal. The preprint may be available, often as a non-typeset versi ...
submitted to arXiv
arXiv (pronounced as "archive"—the X represents the Chi (letter), Greek letter chi ⟨χ⟩) is an open-access repository of electronic preprints and postprints (known as e-prints) approved for posting after moderation, but not Scholarly pee ...
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.][
]
References
Further reading
*
External links
Hires LRGB CCD Image
{{DEFAULTSORT:Krüger 60
Cepheus (constellation)
Local Bubble
M-type main-sequence stars
Flare stars
Binary stars
239960
110893
0860
BD+56 2783
Cephei, DO