WR 156

WR 156 has a Hipparcos parallax of 3.16" indicating a distance of about a thousand light years, although with a fairly large margin of error. Other studies indicate that it is much more distant based on a very high luminosity and faint apparent magnitude.^[6] The Gaia DR1 parallax is 0.07". The margin of error is larger than the measured parallax, but still the indication is for a very large distance.^[7] In Gaia Data Release 2, the parallax is given as 0.2090±0.0251 mas but with a marker that the result may be unreliable.^[8] In Gaia Data Release 3, the solution was adjusted to 0.2749±0.0125 mas, still with significant astrometric noise excess.^[2]

WR 156 has a WR spectrum on the nitrogen sequence, indicating strong emission of helium and nitrogen, but it also shows features of hydrogen. Therefore, it is given a spectral type of WN8h. Its outer layers are calculated to contain 30% hydrogen, one of the highest levels for any galactic Wolf Rayet star.^[4]

WR 156 has a low temperature and slow stellar wind by Wolf Rayet standards, only 39,800 K and 660 km/s respectively. The wind is very dense, with total mass loss of more than 1/100,000 M_☉/year.^[6]

WR 156 is a young hydrogen-rich star, still burning hydrogen in its core but sufficiently luminous to have convected up nitrogen and helium fusion products to its surface. It shows 27% hydrogen at its surface.^[6] It is estimated to have had an initial mass of 50 M_☉ several million years ago.^[4]