Pi Arae

Pi Arae
Location of π Arae (dot within red circle)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ara
Right ascension 17h 38m 05.51512s[1]
Declination –54° 30′ 01.5643″[1]
Apparent magnitude (V) +5.25[2]
Characteristics
Spectral type A5 IV-V[3]
B−V color index +0.20[2]
Astrometry
Radial velocity (Rv)−3.3±3.1[4] km/s
Proper motion (μ) RA: +128.19[1] mas/yr
Dec.: +62.16[1] mas/yr
Parallax (π)46.30 ± 0.19 mas[1]
Distance70.4 ± 0.3 ly
(21.60 ± 0.09 pc)
Absolute magnitude (MV)+2.01[5]
Details
Mass1.73[6] M☉
Radius1.90[7] R☉
Luminosity13.3[5] L☉
Surface gravity (log g)4.36[6] cgs
Temperature8,215±279[6] K
Metallicity [Fe/H]+0.13[5] dex
Rotational velocity (v sin i)54.1±0.4[8] km/s
Age319[6] Myr
Other designations
π Ara, CPD–54° 8403, GJ 683, HD 159492, HIP 86305, HR 6549, SAO 244896[9]
Database references
SIMBADdata

Pi Arae, Latinized from π Arae, is the Bayer designation for a star in the southern constellation of Ara. It is faintly visible to the naked eye with an apparent visual magnitude of +5.25.[2] Based upon an annual parallax shift of 46.30 mas as seen from Earth,[1] it is located 70 light years from the Sun. It is most likely moving closer to the Sun with a radial velocity of −3 km/s.[4]

The stellar classification of this star is A5 IV-V,[3] indicating the spectrum displays the hybrid features of both a main sequence and a more evolved subgiant star. Pi Arae is an estimated 319[6] million years old and is spinning with a projected rotational velocity of 54.1 km/s.[8] The star has 1.73[6] times the mass of the Sun and 1.90[7] times the Sun's radius. It is radiating 13.3[5] times the Sun's luminosity from its photosphere at an effective temperature of about 8,215 K.[6]

Pi Arae displays an excess emission of infrared radiation, which may be explained by circumstellar dust.[10] The thermal emission matches a two component model, consisting of an inner disk of warm crystalline silicate dust and an outer colder disk of dirty ice. The inner disk has a temperature of 173 K and is orbiting roughly 9.1 AU from the host star. The outer disk is 77 K and orbits at a distance of about 117.3 AU. The small size of some of the dust grains indicate the inner disk may have formed relatively recently from collisions between orbiting planetesimals.[11]

Located 55 arc minutes to the north of Pi Arae is the globular cluster NGC 6397.[12]

  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 Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Gontcharov2006 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 c d e f g Cite error: The named reference David2015 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Patel2014 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Diaz2011 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 apjl730_2_L29 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Morales2013 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference OMeara2013 was invoked but never defined (see the help page).