Kapteyn's star

Cordoba Survey	CD −45 ° 1841
Henry Draper Catalog	HD 33793 [1]
Gliese catalog	FY 191 [2]
Hipparcos catalog	HIP 24186 [3]
SAO catalog	SAO 217223 [4]
Tycho catalog	TYC 8078-1749-1 [5]
2MASS catalog	2MASS J05114046-4501051 [6]
Other names	VZ Pictoris • LHS 29

annotation

↑ Calculated from apparent brightness and distance.

Kapteyn's star is a near-Sun star of the class of red sub-dwarfs . Its mass is 38% of the solar mass and its size is just under 3 Jupiter's diameter. Its luminosity reaches about a thousandth of the sun's luminosity. The star is located in the constellation Maler (Pictor) and is only visible as a faint object in the telescope . Due to its location in the southern sky , it can only be observed south of 45 degrees north latitude . The age of the star is estimated to be 13 billion years.

The celestial body is considered to be the closest object of the rare type of halo stars and thus deviates greatly from the usual star movement direction: It moves retrograde in an irregular, elliptical orbit around the Milky Way . This also explains its very high intrinsic motion , the second largest after Barnard's Arrow Star - it is one of the fast runners . In the firmament , the movement runs to the southeast, so the distance to the solar system is constantly increasing.

discovery

Discoverer Jacobus Cornelius Kapteyn

Kapteyn's star was discovered photometrically in 1897 by the Dutch astronomer Jacobus C. Kapteyn . The photo plates were taken at the Cape of Good Hope in the Royal Observatory by David Gill and were used for the systematic creation of a star catalog (Cape Photographic Survey). At the time of its discovery, Kapteyn's star possessed the largest proper motion of all stars and thus replaced the record holder Groombridge in 1830 . With the discovery of Barnard's star in 1916, he was replaced in this position.

Cosmic environment and origin

The celestial body is one of the 30 stars closest to the sun . The closest celestial body to Kapteyn's star at a distance of almost 4 light years is the red subdwarf LHS 1565 / GJ 1061 , others are Sirius at 6.5 and Epsilon Eridani at 7.5 light years away.

According to more recent findings, the celestial body and other stars of the so-called Kapteyn movement group come from a spherical dwarf galaxy that merged with the Milky Way billions of years ago. The stars of the galaxy were pulled apart into a stellar stream , an elongated trail of stars with similar movement in the Milky Way. All that remained of the dwarf galaxy was the compact core that today represents the globular cluster Omega Centauri .

spectrum

The star belongs to the spectral class M, the characteristic of which is a strong titanium oxide (TiO) band. As an eruptive variable star, the celestial body has a variable spectrum. It belongs to the type of flare stars ( UV Ceti stars ). A characteristic of this type of star, which is often found in faintly luminous stars close to the sun, are monumental, unpredictable gas eruptions on the surface that change the luminosity for a short time . The H- line is at 656.8 nm. The increased wavelength compared to the laboratory value shows that the object is moving away from the solar system (optical Doppler effect ). The peculiarity of its star spectrum lies in the relative amplification of the Ca-I and Cr-I lines relative to the strength of the TiO bands. The concentration of heavier elements - its metallicity - is low compared to Sun-like stars, but is normal within its class. Due to the relative proximity of the celestial body and the associated good signal-to-noise ratio, the spectral observations also provide information about a large number of similar, but much more distant and therefore less accessible stars for analysis.

Planets

At the beginning of June 2014 it was announced that an international team of astronomers had discovered two planets with life-friendly properties orbiting Kapteyn's star. The inner planet, Kapteyn b , orbits the star in 48 days and is believed to have five times the mass of Earth. Water could be present in liquid form on its surface. Kapteyn c has an orbital period of 121 days, is probably heavier and probably too cold for liquid water. The discoveries were made using data from the High Accuracy Radial Velocity Planet Searcher spectrometer from the European Southern Observatory in Chile, the Keck Observatory in Hawaii and the Chilean Las Campanas Observatory .

literature

E. Kotoneva et al: A study of Kapteyn's star. In: Astron. Astrophys. 438, 2005, pp. 957-962.
Vincent M. Woolf, George Wallerstein: Chemical abundance analyzes of Kapteyns's Star. In: Monthly Notices of the Royal Astronomical Society. Vol. 350, 2, 2004, pp. 575-579. ( bibcode : 2004MNRAS.350..575W )
D. Segransan, P. Kervella, T. Forveille, D. Queloz: First radius measurements of very low mass stars with the VLTI. In: Astronomy & Astrophysics . 397, L5, 2003.
RF Wing, CA Dean, DJ Macconnell: Temperature, luminosity, and spectrum of Kapteyns Star. In: Astrophysical Journal. 205 (1), 1976, pp. 186- &.
John E. Gizis: M-Subdwarfs: Spectroscopical Classification and Metallicity Scale. In: The Astronomical Journal. Vol. 113, 2, Feb. 1997, p. 806. bibcode : 1997AJ .... 113..806G
JC Kapteyn: Star with the largest known proper motion. In: Astronomical News . 145, 1898, p. 159. ( bibcode : 1897AN .... 145..159K )

Web links

Commons : Kapteyns Stern - collection of images, videos and audio files

Kapteyn's star and halo stars at www.solstatio.com

Data set from the Astronomical Computing Institute at Heidelberg University

Individual evidence

↑ ^a ^b ^c ^d ^e ^f GJ 191. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed September 16, 2018 .
^ Hipparcos catalog (ESA 1997)
↑ ^a ^b ^c P. E. Kervella, F. Arenou, F. Mignard, F. Thévenin: Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly . In: Astronomy & Astrophysics . 623, p. A72. arxiv : 1811.08902 . bibcode : 2019A & A ... 623A..72K . doi : 10.1051 / 0004-6361 / 201834371 .
↑ Pulkovo radial velocities for 35493 HIP stars
↑ Some neighboring stars come from destroyed dwarf galaxies (world of physics)
↑ Discovered planet could be life-friendly (Kurier.at)

[ber-5] Calculated from apparent brightness and distance.

[Simbad-1] ↑ ^a ^b ^c ^d ^e ^f GJ 191. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed September 16, 2018 .

[hip1-2] Hipparcos catalog (ESA 1997)

[Kervella2019-3] P. E. Kervella, F. Arenou, F. Mignard, F. Thévenin: Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly . In: Astronomy & Astrophysics . 623, p. A72. arxiv : 1811.08902 . bibcode : 2019A & A ... 623A..72K . doi : 10.1051 / 0004-6361 / 201834371 .

[Pulkovo-4] Pulkovo radial velocities for 35493 HIP stars

[6] Some neighboring stars come from destroyed dwarf galaxies (world of physics)

[7] Discovered planet could be life-friendly (Kurier.at)