V356 Sagittarii

V356 Sagittarii

Light curves for V356 Sagittarii, in three photometric bands. Plotted from data published by Wilson and Woodward (1995).[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 47m 52.331s[2]
Declination −20° 16′ 28.24″[2]
Apparent magnitude (V) 6.84
Min I: 7.66
Min II: 7.24[3]
Characteristics
Spectral type B3V + A2II[4]
B−V color index 0.120±0.029[5]
Variable type Detached Algol(?)[3]
Astrometry
Radial velocity (Rv)7.0±4.4[5] km/s
Proper motion (μ) RA: +0.525 mas/yr[2]
Dec.: −4.847 mas/yr[2]
Parallax (π)1.4783 ± 0.0289 mas[2]
Distance2,210 ± 40 ly
(680 ± 10 pc)
Orbit[6]
Period (P)8.896106 d
Eccentricity (e)0.01566±0.01360
Argument of periastron (ω)
(secondary)		288.71851±0.42683°
Semi-amplitude (K1)
(primary)		72.17896±1.25080 km/s
Semi-amplitude (K2)
(secondary)		190 km/s
Details
Primary
Mass11.0[7] M☉
Radius9.07[7] R☉
Surface gravity (log g)3.96±0.10[4] cgs
Temperature16,500±750[4] K
Rotational velocity (v sin i)350[4] km/s
Secondary
Mass3.0[7] M☉
Radius13.2[7] R☉
Surface gravity (log g)2.82±0.10[4] cgs
Temperature8,600±300[4] K
Rotational velocity (v sin i)90[4] km/s
Other designations
V356 Sgr, BD−20°5268, GC 25739, HD 173787, HIP 92235, SAO 187294, PPM 268914[8]
Database references
SIMBADdata

V356 Sagittarii is an eclipsing binary star system in the southern constellation of Sagittarius, abbreviated V356 Sgr. It has a peak apparent visual magnitude of 6.84, which decreases to 7.66 during the primary eclipse and 7.24 with the secondary eclipse.[3] Based on parallax measurements, this system is located at a distance of approximately 2,210 light years from the Sun.[2]

This is a double-lined spectroscopic binary system with an orbital period of 8.896 days.[6] It is a massive, interacting system with a circular orbit, where the secondary component has filled its Roche lobe and is transferring matter to its companion. The primary is a B-type main-sequence star with a stellar classification of B3V. It was originally the lower mass component,[9] but now has about 11 times the mass of the Sun.[7] The secondary is an evolved supergiant star[9] with a present-day class of A2II.[4] It has been stripped of much of its original mass,[9] leaving behind the exposed core of a star.[10] The transfer of matter is creating an accretion disk in orbit around the primary.[9]

At least some of the material stripped from the current secondary component has likely been lost from the system. A relatively small change in the orbital period has been observed, but the period is fairly stable over time, which may mean the mass transfer is intermittent.[9] Ultraviolet emission has been observed with the FUSE space observatory, indicating the presence of hot circumstellar matter. This emission shows little variation during a total eclipse, suggesting the material lies perpendicular to the accretion disk. This could represent a bipolar jet of matter from the primary.[11]

  1. ^ Cite error: The named reference Wilson1995 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h Cite error: The named reference Polidan_1988 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Cabezas_et_al_2017 was invoked but never defined (see the help page).
  7. ^ a b c d e Cite error: The named reference van_Rensbergen_et_al_2011 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 c d e Cite error: The named reference Lomax_et_al_2017 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Dominis_et_al_2005 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Peters_Polidan_2004 was invoked but never defined (see the help page).