AX Circini

AX Circini
Observation data
Epoch J2000      Equinox J2000
Constellation Circinus
Right ascension 14h 52m 35.25324s[1]
Declination −63° 48′ 35.4172″[1]
Apparent magnitude (V) 5.91[2] (5.69–6.19)[3]
Characteristics
Spectral type F8 II + B6 V[4]
U−B color index +0.2[5]
B−V color index +0.8[5]
Variable type δ Cep[6]
Astrometry
Radial velocity (Rv)−20.9±4.6[7] km/s
Proper motion (μ) RA: −4.779[1] mas/yr
Dec.: −5.108[1] mas/yr
Parallax (π)1.7449 ± 0.3450 mas[1]
Distanceapprox. 1,900 ly
(approx. 600 pc)
Absolute magnitude (MV)−3.37[8]
Orbit[9]
Period (P)6,532±25 d
Eccentricity (e)0.19±0.02
Longitude of the node (Ω)231±8°
Periastron epoch (T)2,448,500±60 JD
Semi-amplitude (K1)
(primary)		10.0±0.5 km/s
Details
AX Cir A
Mass11.56[10] M☉
Radius45.68[1] R☉
Luminosity2,050[9] L☉
Surface gravity (log g)2.00[11] cgs
Temperature5,443±21[11] K
Metallicity [Fe/H]−0.05[12] dex
Rotational velocity (v sin i)7.4±0.4[13] km/s
AX Cir B
Mass5.57[10] M☉
Other designations
26 G. Cir, AX Cir, CD−63° 1029, HD 130701/2, HIP 72773, HR 5527, SAO 252928, WDS J14526-6349AB[14]
Database references
SIMBADdata
Light curve of AX Circini recorded by NASA's Transiting Exoplanet Survey Satellite (TESS)

AX Circini is a binary star[4] system in the southern constellation of Circinus. It has a nominal magnitude of 5.91,[2] which is bright enough to be visible to the naked eye. Based upon an annual parallax shift of 1.7 mas,[1] it is located roughly 1,900 light-years from the Earth. The system is moving closer with a heliocentric radial velocity of −21 km/s.[7]

This is a spectroscopic binary with an orbital period of 17.88 years and an eccentricity of 0.19.[9] A binary companion was first suspected in 1960, as the spectrum was considered to be composite and there is an ultraviolet excess. The companion was confirmed in 1982, and it was resolved using long baseline interferometry in 2014[4] and 2015.[15] The system has an a sin i value of 6.05 AU, where a is the semimajor axis and i is the (unknown) orbital inclination.[4]

The primary, component A, is a yellow-white-hued bright giant with a stellar classification of F8 II,[16] and it is a classical Cepheid variable.[11] The combined apparent magnitude of the system ranges from 5.69 to 6.19 over 5.273 days.[3] The secondary companion, component B, is a main-sequence star with a class of B6 V and an absolute magnitude of about −0.12.[4]

  1. ^ a b c d e f g Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Klagyivik2009 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference Gallenne2014 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference lloydevans1968 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference evans2005 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Petterson2004 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference tokovinin2008 was invoked but never defined (see the help page).
  11. ^ a b c Cite error: The named reference Usenko2011 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Luck2011 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference AmmlerVonEiff2012 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Gallenne2015 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference gallenne2014 was invoked but never defined (see the help page).