Tau bootis

from Wikipedia, the free encyclopedia
Double star
Tau Bootis (τ Boo)
τ Boo is to the right below η Boo
τ Boo is to the right below η Boo
Observation
dates equinox :  J2000.0 , epoch : J2000.0
AladinLite
Constellation Bear keeper
Known exoplanets

1

Astrometry
Radial velocity (−16.03 ± 0.15) km / s
parallax (63.86 ± 0.34) mas
distance  (51.0 ± 0.3) ly
(15.66 ± 0.08 pc )
Proper movement :
Rec. Share: (−467.91 ± 0.71) mas / a
Dec. portion: (64.70 ± 0.54) mas / a
Individual data
Names A; B.
Observation data:
Right ascension

A. 13 h 47 m 15.737 s
B. 13 h 47 m 15.332 s
declination

A. 2172724.79+ 17 ° 27 ′ 24,790 ″
B. 2172726.432+ 17 ° 27 ′ 26,432 ″
Apparent brightness A. 4.54 mag
B. 11.1 mag
Typing:
Spectral class A. F7 IV-V
B. M3 V
B − V color index A. (+0.52)
Physical Properties:
rel. Brightness
(G-band) 		A. (4.29 ± 0.01) mag
B. (9.47 ± 0.03) mag
Absolute vis.
Brightness M vis 		A. +3.53 mag
B. +10.03 mag
Dimensions A. (1.400 ± 0.070) M ☉
B. (0,4) M ☉
radius A. (1.307 ± 0.065) R ☉
B. 0.58 R ☉
Luminosity A. 3.1 L ☉
B. 0.0084 L ☉
Effective temperature A. 6340 K
B.
Metallicity [Fe / H] A. (0.28)
B.
Age (2.52) billion
Other names
and catalog entries
Bayer name τ bootis
Flamsteed name 4 bootis
Bonn survey BD + 18 ° 2782
Bright Star Catalog HR 5185 [1]
Henry Draper Catalog HD 120136 [2]
SAO catalog SAO 100706 [3]
Tycho catalog TYC 1460-132-1 [4]
Hipparcos catalog HIP 67275 [5]
WDS catalog WDS J13473 + 1727AB
Further designations: Gliese 527,  FK5  507

Template: Infobox double star / maintenance / single coordinates

Tau Bootis (τ Boo / τ Bootis) is a binary star located 16 parsecs (50 light years ) away in the southwest of the Bear Keeper constellation . The system consists of the significantly brighter Tau Bootis A , which is a yellowish star of the spectral class F7 IV-V with an apparent brightness of 4.54 and can therefore also be clearly seen with the naked eye, as well as Tau Bootis B, which is invisible to the naked eye , a red dwarf with an apparent magnitude of 11.1, which orbits Tau Bootis A at a distance of 224 AU in 2,000 years on a strongly eccentric orbit (0.91) that is also inclined by 50.69 ° for the observer on earth is. An exoplanet around Tau Bootis A has been known since 1996 .

Components

Tau Bootis A

Tau Bootis A has a mass of 1.4 solar masses and, with an absolute brightness of 3.53, has a luminosity that is more than three times that of our sun. Its diameter is probably also slightly larger than that of the Sun, but Tau Bootis A is significantly younger with an age of less than 2 billion years. It contains twice as high a proportion of heavy elements as the sun and has a surface temperature of over 6,300 K. The total life span as a main sequence star is significantly shorter than that of the sun at 6 billion years.

A planetary companion was discovered in 1996 (see below). The rotation period of Tau Bootis corresponds to the orbital period of the planet (3.3 days), so that here there is a rare case of bound rotation in which the planet forces the rotation period on its star through corresponding tidal forces. The star has a magnetic field that interacts in complex ways with the nearby planet.

Tau Bootis B

Due to its low luminosity, Tau Bootis B can only be seen with powerful telescopes. The red dwarf has an absolute brightness of 10.03, a mass of only around a third of the solar mass and a radius that corresponds to around 60% of the solar radius; Tau Bootis B belongs to the spectral class M3 V.

Planetary system

→ Main article: Tau Bootis b

In 1996, a team of astronomers led by Geoffrey Marcy and R. Paul Butler discovered a planet around Tau Bootis A. The planet called Tau Bootis b and Tau Bootis Ab was one of the first ever discovered exoplanets. It orbits its central star in around 3.31 days at a distance of around 0.049 AU . Its mass is at least about 4.32 masses of Jupiter .

literature

  • S. Horner et al .: 51 Pegasi and Tau Bootis: Planets or Pulsations? , Los Alamos Conference on Stellar Pulsation, June 1997
  • A. Cameron et al .: Probable detection of starlight reflected from the giant exoplanet orbiting tau Bootis , Nature-Artikel, 1999
  • C. Catala et al .: The magnetic field of the planet-hosting star tau Bootis , MNRAS, 2007

Web links

Individual evidence

  1. ↑ a b tau Boo. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed April 20, 2019 .
  2. ↑ a b c d e f tau Boo A. In: SIMBAD. Center de Données astronomiques de Strasbourg, accessed April 20, 2019 .
  3. ↑ a b c d tau Boo B. In: SIMBAD. Center de Données astronomiques de Strasbourg, accessed April 20, 2019 .
  4. ↑ a b 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 .
  5. ↑ a b c Tau Bootis. Jim Kaler, accessed April 20, 2019 .
  6. ↑ a b tau Boo b. In: Extrasolar Planets Encyclopaedia . Retrieved April 20, 2019 .
  7. ↑ Walker, GAH et al .: MOST detects variability on tau Bootis possibly induced by its planetary companion . arxiv : 0802.2732 .
  8. ^ Butler, R. Paul et al .: Three New "51 Pegasi-Type" Planets . bibcode : 1997ApJ ... 474L.115B .
  9. ↑ Borsa, F .; Scandariato, G .; Rainer, M. et al .: The GAPS Program with HARPS-N at TNG. VII. Putting exoplanets in the stellar context: magnetic activity and Asteroseismology of τ Bootis A . arxiv : 1504.00491 .