Massive Stars in the SDSS-IV-APOGEE Survey: Wolf-Rayet Stars of the WN Type

Roman-Lopes, Alexandre;  Román-Zúñiga, Carlos G.;  Borissova, Jura;  Ramírez-Preciado, Valeria; Hernández, Jesús;  Minniti, Dante
The Astrophysical Journal, Volume 891, Issue 2, id.107 (2020).


In this paper, we describe the results obtained in our study of Galactic Wolf-Rayet stars of the WN type, using the APOGEE2 spectrographs. The APOGEE2 WN star near-infrared spectra presented here were selected through a careful examination of the APOGEE2 DR16 sample, being compound of at least one exemplar of each Wolf-Rayet star from WN4 to WN11 types. Besides the APOGEE2 WN sample, we also identified three new Galactic exemplars of the WN type. The first is WR 147-1, a narrow-lined Wolf-Rayet star of the WN4-5 type located in the direction of the Cygnus-X North complex. The two remaining objects, WR 48-11 and WR 48-12, are found at projected angular distances of several arcminutes southwest from the Danks 1 cluster. WR 48-12 has an estimated heliocentric distance of {7.0}-3.0+5.0 kpc, which is not compatible (within the quoted uncertainties) with that of about 3.8 ± 0.6 kpc for the G305 complex. On the other hand, WR 48-11 has a probable heliocentric distance of {19.0}-4.7+6.5 kpc, which is about three times that of the former, implying that it is probably placed well behind the G305 complex, perhaps at the outermost portion of the Perseus arm.