G79.29+0.46

G79.29+0.46 is a luminous blue variable star candidate located in the Cygnus X star formation region.^[1][5] In the infrared and at radio wavelengths a prominent circular nebula can be seen. This nebula was formed by past mass-loss episodes of the LBV candidate.^[6]

G79.29+0.46

G79.29+0.46 (Spitzer Space Telescope image)
Observation data Epoch J2000      Equinox J2000
Constellation	Cygnus
Right ascension	20h 31m 42.2847s[1]
Declination	+40° 21′ 59.0744″[1]
Apparent magnitude (V)	15.1[2]
Characteristics
Spectral type	B:I[e][3]
Astrometry
Radial velocity (Rv)	39.02±7.30[1] km/s
Proper motion (μ)	RA: −2.925[1] mas/yr Dec.: −5.339[1] mas/yr
Parallax (π)	0.5725±0.0596 mas[1]
Distance	approx. 5,700 ly (approx. 1,700 pc)
Absolute magnitude (MV)	−10[4]
Details
Luminosity	2.51×105[5] L☉
Temperature	20,400[5] K
Other designations
GAL 079.29+00.46, GRS G079.29 +00.46, HBHA 4203-09, IRAS 20298+4011, 2MASS J20314228+4021591, WISE J203142.22+402159.0
Database references
SIMBAD	data

G79.29+0.46 was first reported as a suspected LBV by Higgs, Wendker & Landecker in 1993 with the DRAO Synthesis Telescope, which identified a nebula around a star that was a wind-blown shell.^[7] As an LBV candidate, it has a spectrum with many emission lines, H-alpha being the strongest. The spectrum is similar to other LBVs and Be supergiants. The strength of the H-alpha line suggest very dense winds around this star.^[3] The star is currently losing mass at a rate of 1.4×10⁻⁶ M_☉/year and it is surrounded by a dusty envelope with a temperature of 40 to 1,200 K.^[5] The star is considered only a candidate LBV because it has not shown variability in the optical or near-infrared over 20 years. It has been suggested that it is a LBV in the quiescent stage.^[5]

From radio and infrared images a detached shell can be seen that shows evidence of two mass-loss episodes.^[6] This shell has a mass of 1.51 M_☉ and a radius of 0.66 parsecs,^[5] and it contains carbon monoxide^[8] and ammonia.^[6]

Gallery

• 
  Spitzer and WISE view of G79.29+0.46, the H II-region DR15 (bright object lower left) and the IRDC G79.3+0.3 (dark clouds)^[6]
• 
  The outer shell is best seen between 20 and 70 Microns, here an image by Spitzer and Herschel.
• 
  Radio image of G79.29+0.46 at 1.4 GHz