7 Arietis

7 Arietis
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension 01h 55m 51.03905s[1]
Declination +23° 34′ 38.3509″[1]
Apparent magnitude (V) 5.76[2]
Characteristics
Spectral type K1 III[3]
U−B color index +1.04[4]
B−V color index +1.185[4]
Variable type Eclipsing binary[5]
Astrometry
Radial velocity (Rv)+15.95[6] km/s
Proper motion (μ) RA: +11.050[1] mas/yr
Dec.: −9.513[1] mas/yr
Parallax (π)5.3941 ± 0.1720 mas[1]
Distance600 ± 20 ly
(185 ± 6 pc)
Details
Radius25.0+0.9
−1.4[1] R☉
Luminosity231.3±8.5[1] L☉
Temperature4500+130
−78[1] K
Rotational velocity (v sin i)1.8±1.0[7] km/s
Other designations
7 Ari, RR Arietis, BD+22 284, FK5 2130, HD 11763, HIP 8993, HR 559, SAO 75030[4]
Database references
SIMBADdata

7 Arietis is a binary star[3] system in the northern constellation of Aries. 7 Arietis is the Flamsteed designation. The pair have a combined apparent visual magnitude of 5.76,[2] making it faintly visible to the naked eye from dark suburban skies. Based upon an annual parallax shift of 5.39 mas,[1] it is approximately 600 light-years (180 parsecs) distant from the Earth, give or take a 30 light-year margin of error. It is drifting further away from the Sun with a radial velocity of +16 km/s.[6]

This is listed as an eclipsing binary system with a period of 47.9 days and has the variable star designation RR Arietis. During each eclipse of the primary star, the magnitude of the system decreases by 0.40. The eclipse of the secondary reduces the magnitude by 0.35.[5] The primary component of the system is an evolved giant star with a stellar classification of K1 III.[3] It is about 25 times the size of the Sun and is radiating 231 times the Sun's luminosity from its photosphere at an eeffective temperature of 4,500 K.[1]

The eclipsing binary nature of this star has been disputed by Italian astronomer Ennio Poretti.[8] Observations made as part of the British Astronomical Association eclipsing binaries program by Tristram Brelstaff were also unable to confirm eclipses.[9]

  1. ^ a b c d e f g h i j Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference aaa431_773 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference aaa446_2_785 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference aaa430_165 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference aaa395_97 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Poretti1984 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Isles1985 was invoked but never defined (see the help page).