Upsilon Pegasi

Upsilon Pegasi
Location of υ Pegasi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pegasus
Right ascension 23h 25m 22.78350s[1]
Declination +23° 24′ 14.7606″[1]
Apparent magnitude (V) 4.40[2]
Characteristics
Evolutionary stage Hertzsprung gap[3]
Spectral type F8III[4]
U−B color index +0.14[2]
B−V color index +0.61[2]
Astrometry
Radial velocity (Rv)−8.59[5] km/s
Proper motion (μ) RA: +192.19[1] mas/yr
Dec.: +36.12[1] mas/yr
Parallax (π)19.14 ± 0.18 mas[1]
Distance170 ± 2 ly
(52.2 ± 0.5 pc)
Absolute magnitude (MV)0.83[6]
Details
Mass2.17[7] M☉
Radius5.97+0.36
−0.19[8] R☉
Luminosity43.2±0.8[8] L☉
Surface gravity (log g)3.22[7] cgs
Temperature6,061+97
−176[8] K
Metallicity [Fe/H]−0.01[6] dex
Rotational velocity (v sin i)73.4[3] km/s
Other designations
Alkarab, υ Peg, 68 Pegasi, BD+22°4833, FK5 881, GC 32585, HD 220657, HIP 115623, HR 8905, SAO 91253[9]
Database references
SIMBADdata

Upsilon Pegasi, Latinised from υ Pegasi, is a star within the great square[10] in the northern constellation of Pegasus. It has the proper name Alkarab /ˈælkəræb/.[11] This object has a yellow-white hue and is faintly visible to the naked eye with an apparent magnitude of 4.40.[2] It is located at a distance of approximately 170 light-years from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −8.6 km/s.[5] The star is moving through the galaxy at a speed of 50.6 km/s relative to the Sun. Its projected galactic orbit carries it between 18,600 and 26,300 light-years from the center of the galaxy.[6]

This object is an aging giant star with a stellar classification of F8III.[4] It is currently in the Hertzsprung gap and is a source of X-ray emission.[3] The star has 2.2[7] times the mass of the Sun and is spinning with a projected rotational velocity of 73.4 km/s.[3] It has an iron abundance of −0.01 dex, or 97.7% of the Sun's. Upsilon Pegasi has six times the girth of the Sun and is radiating 43 times the Sun's luminosity at an effective temperature of 6,061 K.[8]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Ducati2002 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Schröder2009 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Gray2001types was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Massarotti2008 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference XHIP was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference AllendePrieto was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Harrington2010 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference IAU-LSN was invoked but never defined (see the help page).