7 Aquarii

7 Aquarii
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 20h 56m 54.02626s[1]
Declination −09° 41′ 51.1610″[1]
Apparent magnitude (V) 5.499[2] (5.62 + 11.4)[3]
Characteristics
Spectral type K4 III[4]
B−V color index +1.474±0.006[5]
Variable type Suspected[6]
Astrometry
Radial velocity (Rv)−32.4±1.6[7] km/s
Proper motion (μ) RA: −5.577[1] mas/yr
Dec.: −10.245[1] mas/yr
Parallax (π)4.9495 ± 0.1309 mas[1]
Distance660 ± 20 ly
(202 ± 5 pc)
Absolute magnitude (MV)−0.61[5]
Details
Radius46[8] R☉
Luminosity403.66[5] L☉
Surface gravity (log g)1.650[2] cgs
Temperature3,990[2] K
Metallicity [Fe/H]−0.17[2] dex
Other designations
NSV 13419, BD−10° 5553, HD 199345, HIP 103401, HR 8015, SAO 144968, ADS 14449, WDS J20569-0942[9]
Database references
SIMBADdata

7 Aquarii, abbreviated 7 Aqr, is a binary star[3] system in the zodiac constellation of Aquarius. 7 Aquarii is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 5.5;[2] the brighter component is baseline magnitude 5.62 while the faint secondary is magnitude 11.4.[3] As of 2002, the pair had an angular separation of 2.10″ along a position angle of 165°.[10] The distance to this system, based upon an annual parallax shift of 4.9 mas,[1] is around 660 light years. It is moving closer to the Earth with a heliocentric radial velocity of −32 km/s.[7]

The primary component is an aging giant star with a stellar classification of K4 III.[4] It is a suspected variable star of unknown type with a maximum magnitude of 5.48.[6] The interferometry-measured angular diameter of this star, after correcting for limb darkening, is 2.14±0.02 mas,[11] which, at its estimated distance, equates to a physical radius of about 46 times the radius of the Sun.[8] The star is radiating 404[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,990 K.[2]

  1. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference McWilliam1990 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference lang2006 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 WDSC2014 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Richichi2005 was invoked but never defined (see the help page).