HD 100655

HD 100655 / Formosa
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Leo
Right ascension 11h 35m 03.75298s[1]
Declination +20° 26′ 29.5637″[1]
Apparent magnitude (V) +6.45[2]
Characteristics
Evolutionary stage giant star
Spectral type G9 III[3]
B−V color index 1.010±0.015[2]
Astrometry
Radial velocity (Rv)−5.2±0.3[4] km/s
Proper motion (μ) RA: –59.695[1] mas/yr
Dec.: –1.047[1] mas/yr
Parallax (π)7.2613 ± 0.0472 mas[1]
Distance449 ± 3 ly
(137.7 ± 0.9 pc)
Absolute magnitude (MV)1.02[2]
Details[5]
Mass2.2±0.1 M☉
Radius8.8±0.1 R☉
Luminosity40.8±0.3 L☉
Surface gravity (log g)2.89±0.02 cgs
Temperature4,918±8 K
Metallicity [Fe/H]0.07±0.03[6] dex
Rotational velocity (v sin i)1.6±1.0[7] km/s
Age900±200 Myr
Other designations
Formosa, BD+21° 2331, Gaia DR2 3979226627820659072, HD 100655, HIP 56508, HR 4459, SAO 81886, 2MASS J11350375+2026295[8]
Database references
SIMBADdata
Exoplanet Archivedata

HD 100655 is a star in the zodiac constellation of Leo, located 449[1] light years away from the Sun. It has an apparent visual magnitude of +6.45,[2] which makes it a challenge to see with the naked eye under ideal viewing conditions. The star is moving closer to the Earth with a heliocentric radial velocity of −5 km/s.[4] It has one confirmed planet.[7]

The star HD 100655 is named Formosa. The name was selected in the NameExoWorlds campaign by Taiwan, during the 100th anniversary of the IAU. Formosa is the historical name of Taiwan used in the 17th century, meaning beautiful in Portuguese. The planet HD 100655 b is named Sazum, after the township Yuchi and it means water in the language of the Thao people.[9][10]

This is an evolved giant star with a stellar classification of G9 III.[3] It is a red clump giant,[11] which means it is currently on the horizontal branch and is generating energy through helium fusion at its core. This star is around 900 million years old with 2.2 times the mass of the Sun and has expanded to 8.8 times the Sun's radius. It is radiating 4,918 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,918 K.[5]

  1. ^ a b c d e f Cite error: The named reference gaia_dr2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Halliday1955 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Bonfanti2015 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Sousa2015 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Omiya2012 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ "Approved names". NameExoworlds. Retrieved 2020-01-02.
  10. ^ "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
  11. ^ Cite error: The named reference Sato2012 was invoked but never defined (see the help page).