Luyten's star

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Star
Luyten's star
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Small dog
Right ascension 07 h 27 m 24.5 s
declination + 05 ° 13 ′ 32.8 ″
Apparent brightness 9,872 likes
Typing
Known exoplanets 2
B − V color index 1.571 
U − B color index 1.115 
Spectral class M3.5V
Astrometry
Radial velocity 18.22 ± 0.1 km / s
parallax 262.98  mas
distance 12.20 ± 0.04  ly
3.74 ± 0.01  pc
Visual absolute brightness M vis 11.94 mag
Proper movement 
Rec. Share: 572.51 ± 1.50  mas / a
Dec. portion: -3693.51 ± 0.96  mas / a
Physical Properties
Dimensions 0.29  M ☉
radius 0.293 ± 0.027  R ☉
Luminosity

0.0027 ± 0.0066  L ☉

Effective temperature 3159 ± 49  K
Metallicity [Fe / H] 0.09 ± 0.17
Rotation time 99 d
Other names
and catalog entries
Bonn survey BD + 05 ° 1668
Gliese catalog FY 273 [1]
Hipparcos catalog HIP 36208 [2]
Tycho catalog TYC 173-3208-1 [3]
2MASS catalog 2MASS J07272450 + 0513329 [4]

Luyten's star is a red dwarf in the constellation Little Dog . At a distance of just over 12 light years , it is one of the neighbors around the sun . The star has a planetary system with two known exoplanets . It is named after the Dutch astronomer Willem Jacob Luyten , who, together with Edwin G. Ebbighausen, discovered the star's high self-motion in 1935 .

Due to its low apparent magnitude of only around 9.9 mag , Luyten's star cannot be observed with the naked eye. In the night sky, it is east of Prokyon and south of Gomeisa , the two brightest stars in the constellation Little Dog.

properties

Like all red dwarfs, Luyten's star is significantly smaller, less massive and less faint than the sun. Its diameter and mass are far less than a third of those of the sun. The luminosity is also very low at 0.27% of the sun's luminosity.

Planetary system

The astrometric evaluation of photo plates and measurements between 1937 and 1980 suggested as early as the 1980s that Luyten's star could have a planetary companion. It was based on a planet with either 1.1, 0.7 or 0.4 times the mass of Jupiter , which should orbit the star once in 10, 20 or 40 years. The later search for such a companion using the radial velocity method was unsuccessful.

In March 2017, a team of astronomers led by Nicola Astudillo-Defru announced the discovery of two planets around Luyten's star after measurements with the Échelle spectrograph HARPS from the European Southern Observatory (ESO). The two planets with the designations GJ 273 b and GJ 273 c have approximately 2.9 and 1.2 times the minimum mass of the earth and orbit their central star at a very short distance. GJ 273 b takes around 18.7 days and GJ 273 c around 4.7 days to orbit Luyten's star. Despite the short distance, the outer planet GJ 273 b is still in its habitable zone because of the star's weak luminosity .

Planetary system from Luyten's star
Planet
(by distance from the star) 		Discovery
(year) 		Mass
(in M ⊕ ) 		Cycle time
(in days) 		Major semi-axis
(in AU ) 		eccentricity
FY 273 c 2017 1.18 ± 0.16 4.7234 ± 0.0004 0.036467 ± 0.0000002 0.036467 +0.13−0.12
FY 273 b 2017 2.89 +0.27−0.26 18.6498 + 0.0059−0.0052 0.091101 +0.000019−0.000017 0.10 +0.09−0.07

Closest neighbors

Luyten's star is only 1.2 light years away from Prokyon, the main star of the constellation Little Dog, which is a binary star system made up of a subgiant and a white dwarf . It was closest to Prokyon 600 years ago and has been moving away from it since then. Its closest approach to the sun happened 13,000 years ago. The second closest neighbor of Luyten's star is Ross 614 , a binary star system made up of two red dwarfs 3.9 light years away. This is followed by the red dwarfs DX Cancri and LTT 12352 , 5.5 and 5.6 light years away, respectively.

The vicinity of Luyten's star also includes the 5.8 light-years distant double star system Sirius , which is the brightest star in the night sky when viewed from Earth. All the other neighbors of Luyten's star are, like himself, faint red dwarfs.

Web links

Individual evidence

  1. ↑ a b c d e f Simbad: BD + 05 1668 - High proper-motion star. Retrieved March 18, 2017 .
  2. ↑ a b c d e f g h i j k Astudillo-Defru, N. et al .: The HARPS search for southern extra-solar planets XLI. A dozen planets around the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628, and GJ 3293 . arxiv : 1703.05386 .
  3. ↑ a b c Koen, C. et al .: UBV (RI) C photometry of Hipparcos red stars . doi : 10.1046 / j.1365-8711.2002.05403.x .
  4. ↑ Luyten, WJ; Ebbighausen, EG: A Faint Star of Large Proper Motion . bibcode : 1935BHarO.900 .... 1L .
  5. ↑ a b c d e SolStation.com: Luyten's Star. Retrieved March 18, 2017 .
  6. ↑ SIMBAD: Annotations on object BD + 05 1668. Retrieved March 18, 2017 .
  7. ^ García-Sánchez, J. et al .: Stellar encounters with the solar system . bibcode : 2001A & A ... 379..634G .