Iota Capricorni

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Star
ι Capricorni
ι Cap in the constellation "Capricorn"
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Capricorn
Right ascension 21 h 22 m 14.8 s
declination -16 ° 50 ′ 4.4 ″
Apparent brightness 4.44 mag
Typing
B − V color index 0.91 
U − B color index 0.56 
R − I index 0.48 
Spectral class G8 III
Variable star type BY Dra 
Astrometry
Radial velocity (12.18 ± 0.13) km / s
parallax (16.58 ± 0.27)  mas
distance (197 ± 3)  ly
(60.3 ± 0.1)  pc
Proper movement 
Rec. Share: (30.00 ± 0.26)  mas / a
Dec. portion: (4.52 ± 0.14)  mas / a
Physical Properties
Dimensions 2.6  M ☉
radius 11  R ☉
Luminosity

74  L ☉

Effective temperature 5080  K
Metallicity [Fe / H] −0.15
Other names
and catalog entries
Bayer name ι Capricorni
Flamsteed name 32 Capricorni
Bonn survey BD −17 ° 6245
Bright Star Catalog HR 8167 [1]
Henry Draper Catalog HD 203387 [2]
Hipparcos catalog HIP 105515 [3]
SAO catalog SAO 164346 [4]
Tycho catalog TYC 6360-1220-1 [5]Template: Infobox star / maintenance / specification of the TYC catalog
2MASS catalog 2MASS 21221480-1650042 [6]
Other names FK5 1561

Iota Capricorni (ι Cap) is a star in the constellation Capricorn . It has an apparent magnitude of 4.4 mag and its distance is approximately 197 light years .

Iota Capricorni is a yellow giant star about 2.6 times the mass, 11 times the diameter and 74 times the luminosity of the sun . Its surface temperature is around 5100 K.

The star is a variable star of the BY Draconis type , its brightness fluctuates slightly around 0.06 mag. The fluctuations in brightness of these variables are caused by star spots on their rotating surface.

Scientific research

In a study, a projected equatorial rotation speed v ∙ sin i of about 6 km / s and a rotation period of 68 days were derived for Iota Capricorni from the brightness fluctuations over a period of 3 years .

A survey of the entire sky with the X-ray satellite ROSAT was able to detect an emission of X-rays from Iota Capricorni . The magnetic field on its surface could also be definitely detected and its strength determined to be around 0.8 mT.

Individual evidence

  1. ^ A b c VizieR: Hipparcos, the New Reduction (van Leeuwen, 2007) - The Astrometric Catalog
  2. ↑ a b c VizieR: Stellar Photometry in Johnson's 11-color system (Ducati, 2002)
  3. ↑ VizieR: Michigan Catalog of HD stars, Vol.4 (Houk +, 1988)
  4. ↑ Vizier: RV and vsini of southern stars (de Medeiros +, 2014)
  5. ↑ a b c d e VizieR: G and K giant stars stellar parameters (Reffert +, 2015)
  6. ↑ VizieR: AAVSO International Variable Star Index VSX (Watson +, 2006-2014)
  7. ↑ GW Henry, FC Fekel, DS Hall: An Automated Search for Variability in Chromospherically Active Stars. In: The Astronomical Journal. Vol. 110, 1995, doi: 10.1086 / 117740 , pp. 2926-2967 ( bibcode : 1995AJ .... 110.2926H )
  8. ↑ M. Hünsch, JHMM Schmitt, W. Voges: The ROSAT all-sky survey catalog of optically bright late-type giants and supergiants. In: Astronomy & Astrophysics Supplement Series. Vol. 127, 1998, doi: 10.1051 / aas: 1998347 , pp. 251–255 ( PDF; 323 KB )
  9. ↑ M. Aurière, R. Konstantinova-Antova, C. Charbonnel, GA Wade, S. Tsvetkova, P. Petit, B. Dintrans, NA Drake, T. Decressin, N. Lagarde, J.-F. Donati, T. Roudier, F. Lignières, K.-P. Schröder, JD Landstreet, A. Lèbre, WW Weiss, J.-P. Zahn: The magnetic fields at the surface of active single G-K giants. In: Astronomy & Astrophysics. Vol. 574, A90, 2015, doi: 10.1051 / 0004-6361 / 201424579 , pp. 1–30 ( PDF; 1.11 MB )