Xi Bootis

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Double star
ξ bootis
Observation
dates equinox :  J2000.0 , epoch : J2000.0
AladinLite
Constellation Bear keeper
Right ascension 14 h 51 m 23.380 s
declination + 19 ° 06 ′ 01.70 ″
Apparent brightness  4.59 likes
Astrometry
Radial velocity A: +3.00 ± 0.90 km / s /
B: +3.10 km / s
parallax 148.98 ± 0.48 mas
distance  21.893 ± 0.07 Lj
(6,712 ± 0.02 pc )
Proper movement :
Rec. Share: A: 154.98 ± 0.40
89.70 ± 4.90 mas / a
Dec. portion: A: −66.43 ± 0.45
−147.30 ± 5.10 mas / a
orbit 
period 151.505 ± 0.17 J.
Major semi-axis 4.9044 ± 0.0027 "
eccentricity 0.5117 ± 0.0006
Orbit inclination 140.037 ± 0.095
Argument of the node 168.100 ± 0.164 °
Epoch of the periastron JD 1909.361 ± 0.024
Argument of the periapsis 23.917 ° ± 0.214
Individual data
Names A; B.
Observation data:
Apparent brightness A. 4.76 likes
B. 6.97 likes
Typing:
Spectral class A. G8.0Ve
B. K5.0Ve
B − V color index A. 0.725
B. 1.156
U − B color index A. 0.230
B. 1.150
Physical Properties:
Absolute vis.
Brightness M vis 		A. 5.57 mag
B. 7.84 likes
Dimensions A. 0.881 ± 0.040 M ☉
B. 0.700 ± 0.050 M ☉
radius A. 0.863 ± 0.011 R ☉
B. 0.610 R ☉
Luminosity A. 0.6041 ± 0.0040 L ☉
B. 0.061 L ☉
Effective temperature A. 5551 ± 20 K
B. 4350 ± 150 K
Metallicity [Fe / H] A. -0.21 ± 0.08
B.
Rotation time A. 6.31 d
B. 11.94 d
Age 6.5 billion years or
200 million years
Other names
and catalog entries
Bayer name ξ Bootis
Flamsteed name 37 bootis
Bonn survey BD + 19 ° 2870
Bright Star Catalog HR 5544 [1]
Henry Draper Catalog HD 131156 [2]
SAO catalog SAO 101250 [3]
Hipparcos catalog HIP 72659 [4]
Tycho catalog TYC 1481-722-1 [5] TYC 1481-722-2 [6]
WDS catalog WDS J14514 + 1906
Further designations: GJ 566 • STF 1888 • SVS 2491 • GCTP 3360 • 2MASS J14512328 + 1906034

Xi Bootis (ξ Bootis / ξ Boo) is a double star system in the Bear Keeper constellation . Xi boötis AB is 21.9 light years from the sun away and is one of the solar neighborhood systems . The lighter, larger component has an apparent brightness of at least 4.76 and is therefore visible to the naked eye. With a smaller telescope , the two components can also be observed separately.

Astrometry

The most precise measurement of the parallax of 148.98 ± 0.48 mas comes from the year 2007. This results in a distance of the system to the earth of around 21.9 light years.

The proper motion in the sky that can be observed from earth is 0.15 arc seconds per year  .

Determining the distance for Xi bootis

year source Parallax (mas) Distance (pc) Distance (Lj) Distance ( Pm )
1970 Woolley
et al. 		148.00 ± 6.00 6.757 +0.29−0.26 22.038 +0.93−0.86 208.49 +8.81−8.12
1991 Gliese
& Jahreiß 		149.10 ± 3.60 6.707 +0.17−0.16 21.875 +0.54−0.52 206.95 +5.12−4.88
1995 Yale Parallax Catalog 149.70 ± 1.70 6.680 +0.08−0.08 21.787 +0.25−0.24 206.12 +2.37−2.31
1997 Hipparcos
catalog 		149.26 ± 0.76 6.700 +0.03−0.03 21.851 +0.11−0.11 206.73 +1.06−1.05
1997 Tycho A
Tycho B 		137.90 ± 3.80
144.90 ± 6.40 		7.252 +0.21−0.19
6.901 + 0.32−0.29 		23.652 +0.67−0.63
22.509 +1.04−0.95 		223.76 +6.34−6.00
212.95 +9.84−9.01
1999 Söderhjelm
 147.10 ± 0.80 6.798 +0.04−0.04 22.172 +0.12−0.12 209.77 +1.15−1.13
2007 van
Leeuwen 		148.98 ± 0.48 6.712 +0.02−0.02 21.893 +0.07−0.07 207.12 +0.67−0.67
2012 RECONS
Top 100 		147.57 ± 0.72 6.776 +0.03−0.03 22.102 +0.11−0.11 209.10 +1.03−1.02

Non-trigonometric distance determinations are marked in italics . The most precise determination is marked in bold .

System Xi Bootis AB

The visual distance between the two components, which move in a wide, highly elliptical orbit ( eccentricity 0.51) around the common center of mass , averages 4.9 arc seconds ( major orbit half-axis ). With the heliocentric distance of the stars, this corresponds to about 33.6 astronomical units (AU) - slightly more than the distance from Neptune to the sun . Due to the high eccentricity, their distance varies from 16.5 to 50.7 AU; they need 151.5 years for a joint circumnavigation. When viewed from Earth, its orbit is inclined at 139 ° .

As a system, Xi Bootis belongs to the spectral class G5.0Ve. The total mass of the system is about 1.6 solar masses (M☉).

The age of the stars is difficult to determine. While strong chromospheric activities at Xi Bootis A suggest that the star was only 60 to 200 million years old , other measurements indicate an age of 6.5 billion years .

Xi Bootis A

The main star ξ Bootis A, a yellow main sequence star , has a variable apparent magnitude of between +4.53 and +4.76 mag and belongs to the spectral class G8.0Ve. The variability interval is 10.137 days. The rotation of the star itself, on the other hand, is 6.31 days.

Its diameter is 0.863 solar radii ; this corresponds to 1'201'900 km in the total diameter of the star. The mass is 88.1% of the mass of the sun . In contrast, Xi Bootis A has only about 60% of the sun's luminosity. The metallicity of the star is also reduced compared to the sun.

Xi Bootis A often has the names Gliese 566 A, HD 131156 A, Struve 1888 A and BD + 19 ° 2870 A in various star catalogs .

Asteroid belt

Infrared measurements for debris disks from 1997 indicated the existence of a Kuiper belt-like asteroid belt for the main star Xi Bootis A for the first time . The estimated minimum total mass of this dust disk is calculated to be 2.4 times (± 0.7) the mass of the Earth's moon (M☾) (compared to the 8.2 M☾ for the Kuiper belt). This fits well with other mass calculations calculated so far, such as for Wega (0.7 M☾), Fomalhaut (1.5 M☾) and Beta Pictoris (7.8 M☾). In comparison, the inner asteroid belt in the solar system has only 0.04 M☾. The temperature of the belt is 39  K (−234  ° C )

Xi Bootis B

The +6.97 mag bright companion star ξ Bootis B belongs to the spectral class K5.0Ve and is classified as an orange main sequence star. Its diameter is 0.61 solar radii ; this corresponds to about 850,000 km in the diameter of the star. The mass is between 66% and 72% of the mass of the sun , whereas the luminosity is only 6.1% of the sun - and therefore only about 10% of the luminosity of Xi Bootis A.

Xi Bootis B also bears the names Gliese 566 B, HD 131156 B, Struve 1888 B and BD + 19 ° 2870 B.

System Xi Bootis AB

Surname Another name Spectral
class 		Coordinates Angular
distance
as 		Distance
in AU 		Eccentric Apparent
Helligk.
like 		Diameter
R☉ 		Mass
M☉ 		Temp.
K
ξ Bootis A
37 Bootis A 		Gliese 566 A
HD 131156 A 		G8.0Ve 14h 51m 23.286s
+ 19 ° 06 ′ 02.25 ″ 		0.00 0.00 0.51 4.76 0.863 0.88100 5551
Asteroid
Belt ξ Bootis A 		- Debris disk 14h 51m 23.286s
+ 19 ° 06 ′ 02.25 ″ 		? ? 0.00 - - 0.00009 39
ξ Bootis B
37 Bootis B 		Gliese 566 B
HD 131156 B 		K5.0Ve 14h 51m 23.052s
+ 19 ° 06 ′ 06.77 ″ 		4.90 33.60 0.51 6.07 0.610 0.70000 4350

Possibility of substellar companions

For the existence of a substellar companion in any binary system, areas in which the object can remain in a stable orbit for long periods of time are a necessary condition. Circular orbits should therefore be very close to one of the two stars. For a hypothetical planet in this system in a circular orbit, a maximum distance of 3.8 AU for Xi Bootis A and 3.5 AU for Xi Bootis B was calculated (in our solar system this would correspond to the outer areas of the asteroid belt).

No evidence of substellar companions has been found with Xi Bootis A. However, it cannot be ruled out that due to the comparatively high luminosity of both stars, especially the A star, a terrestrial planet close to the star is very difficult to identify with the current methods. The Habitable Zone for Xi Bootis A was calculated to be 0.70 AU (roughly equivalent to the distance between Venus and the Sun), which would correspond to an orbital period of 221 days.

At Xi Bootis B, on the other hand, there have been indications since 1943, when measurements of periodic orbital disturbances in its orbit indicated the existence of an exoplanet . The measurements were made at the Sproul Observatory from 1939 to 1942 and indicated a companion with a period of 2.2 years, with a calculated mass of 0.1 solar masses. In 1988, further changes in the speed of the B star were found, which would correspond to a companion of 1 to 9 times Jupiter's mass . These changes in speed were too small to originate from an object orbiting the A star, as it has too much mass for that. The habitable zone for this star is calculated at 0.25 AU (within Mercury's orbit ). This would correspond to a period of rotation of only 54 days.

A planet orbiting both stars, on the other hand, would need a distance of at least 108 AU for a stable orbit.

Closest neighbors

Surname Another name Spectral
class 		Distance
LJ 		Coordinates
RA / DA 		Apparent
Helligk.
like 		Parallax
mas 		Sun
distance
LJ
Gliese 526
Lalande 25372 		Wolf 498
HD 119850 		M4.0V 6.9 13h 45m 43.777s
+ 14 ° 53 ′ 29.46 ″ 		8.50 185.49 ± 1.10 17,584
Gliese 514
BD + 11 ° 2576 		Ross 490
HIP 65859 		M1.0V 9.2 13h 29m 59.786s
+ 10 ° 22 ′ 37.79 ″ 		9.03 130.62 ± 1.05 24,970

Individual evidence

  1. ↑ Hog et al. (2000): TYC 1481-722-1 in the Tycho-2 catalog. Retrieved July 4, 2015 .
  2. ↑ SIMBAD: Ksi Bootis. Retrieved July 4, 2015 .
  3. ↑ Montes et al. (2001): HIP 72659 in Late-type stars members of young groups. Retrieved July 4, 2015 .
  4. ↑ a b c d Gliese W .; Jahreiß H. (1991): Gliese 566 AB in the Nearby Stars Catalog. Retrieved July 4, 2015 .
  5. ↑ a b c d van Leeuwen F. (2007): HIP 72659 in the Hipparcos New Reduction catalog. Retrieved July 4, 2015 .
  6. ↑ a b Hog et al. (2000): TYC 1481-722-2 in the Tycho-2 catalog. Retrieved July 4, 2015 .
  7. ↑ a b c d e f Fernandes J. et al .: Fundamental stellar parameters for nearby visual binary stars: ξBoo + . 1998, bibcode : 1998A & A ... 338..455F .
  8. ↑ a b c Mason et al. (2001-2014): WDS J14514 + 1906 in the Washington Visual Double Star Catalog. Retrieved July 4, 2015 .
  9. ↑ a b Perryman et al. (1997): TYC 1481-722-1 in the Hipparcos and Tycho Catalog. Retrieved July 4, 2015 .
  10. ↑ a b c d e Boyajian TS et al. (2013) PDF: Stellar diameters and temperatures III. Retrieved July 4, 2015 .
  11. ↑ Wood BE, Linsky JL (2010) PDF: Resolving the ξ Boo Binary with CHANDRA. Retrieved July 4, 2015 .
  12. ↑ Mamajek EE, Hillenbrand LA (2008): Improved Age Estimation for Solar-Type Dwarfs Using Activity. Retrieved July 4, 2015 .
  13. ↑ Woolley et al. (1970): Woolley 566 AB. Retrieved July 3, 2015 .
  14. ↑ Van Altena WF et al. (1995): GCTP 3360. Retrieved July 3, 2015 .
  15. ↑ Perryman et al. (1997): HIP 72659. Retrieved July 3, 2015 .
  16. ↑ Perryman et al. (1997): TYC 1481-722-2 in the Hipparcos and Tycho Catalog. Retrieved July 4, 2015 .
  17. ↑ Söderhjelm (1999): HIP 72659. Retrieved July 3, 2015 .
  18. ↑ RECONS (Research Consortium On Nearby Stars) (2012): The 100 nearest star systems. Retrieved July 3, 2015 .
  19. ↑ a b Sol Company (1998 - 2002) PDF: Xi Bootis AB at Solstation. Retrieved July 4, 2015 .
  20. ^ Barry, DC: The chromospheric age . 2003, bibcode : 1988ApJ ... 334..436B .
  21. ↑ a b Holmes EK et al. (2003) PDF: A survey of nearby main-sequence stars for submillimeter emission. Retrieved July 4, 2015 .
  22. ↑ Hinshaw G. (1997) PDF: Science Requirements Document. Archived from the original on September 17, 2006 ; Retrieved July 4, 2015 .
  23. ↑ SIMBAD: Ksi Bootis A. Accessed July 4, 2015 .
  24. ↑ SIMBAD: Ksi Bootis B. Accessed July 4, 2015 .
  25. ↑ Jaime LG et al. (2012): Regions of dynamical stability. Retrieved July 4, 2015 .
  26. ^ Campbell B. et al .: A search for substellar companions to solar-type stars . 1988, bibcode : 1988ApJ ... 331..902C .
  27. ↑ SIMBAD: HD 119850. Accessed July 4, 2015 .
  28. ↑ SIMBAD: BD + 11 ° 2576. Retrieved July 4, 2015 .