V923 Aquilae

V923 Aquilae

A photoelectric (yellow) light curve for V923 Aquilae, plotted from data presented by Lynds (1960).[1] The length of a full phase cycle is 0.8518 days.
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 30m 33.12199s[2]
Declination +03° 26′ 39.8583″[2]
Apparent magnitude (V) 6.06[3]
5.98 to 6.18[4]
Characteristics
Evolutionary stage Main sequence[5]
Spectral type B7III[6]
U−B color index −0.31[3]
B−V color index −0.019±0.008[7]
Variable type Be star[4]
Astrometry
Radial velocity (Rv)−26.0±7.4[7] km/s
Proper motion (μ) RA: 11.717[2] mas/yr
Dec.: 3.089[2] mas/yr
Parallax (π)3.6705 ± 0.0607 mas[2]
Distance890 ± 10 ly
(272 ± 5 pc)
Absolute magnitude (MV)−0.87[7]
Details[5]
Primary
Mass6.2±0.3 M☉
Luminosity1517+158
−143 L☉
Surface gravity (log g)3.64±0.21 cgs
Temperature16,580±400 K
Rotational velocity (v sin i)275±17 km/s
Secondary
Mass~0.5 M☉
Other designations
V923 Aql, BD+03°4043, HD 183656, HIP 95929, HR 7415, SAO 0124704[8]
Database references
SIMBADdata

V923 Aquilae is a variable binary star[9] system in the equatorial constellation of Aquila. It has the designation HD 183656 from the Henry Draper Catalogue; V932 Aql is the variable star designation. The system is dimly visible to the naked eye with an apparent visual magnitude that fluctuates around 6.06.[3] It is located at a distance of approximately 890 light years from the Sun based on parallax,[2] but is drifting closer with a radial velocity of around −26 km/s.[7]

This system was first identified as a likely spectroscopic binary by W. E. Harper in 1937, who noted it showed "narrow intense lines of peculiar spectrum".[10] P. W. Merrill and C. G. Burwell identified it as a shell star in 1949.[11][12] Merrill and A. L. Lowen showed in 1953 that the shell displayed large radial velocity variations.[13] A photometric study by C. R. Lynds in 1960 showed the system varied in brightness with an amplitude of more than 0.1 in magnitude and a characteristic period of 0.85 days, although it does not behave periodically over long time intervals.[1]

A more thorough investigation by P. Koubský and associates in 1989 using long-term radial velocity measurements determined this is a spectroscopic binary with an orbital period of 214.75 days. There is also an overlaying long-term cyclical variation of changing amplitude and period. The modelled binary system shows a primary with a class of around B5–7e and a low mass secondary separated by around 250 times the radius of the Sun (250 R☉). They hypothesized that the long-term variation was due to an envelope created by a mass transfer from the secondary component to the primary.[14] However, the mass transfer concept was later brought into question and remains unverified as of 2004.[9]

  1. ^ a b Cite error: The named reference Lynds1960 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference haupt1974 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Zorec_et_al_2016 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Houk_Swift_1999 was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference aa417_679 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Harper1937 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Merrill_Burwell_1949 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Bidelman1950 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Merrill_Lowen_1953 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Koubský1989 was invoked but never defined (see the help page).