A New Galactic Wolf-Rayet Star in Centaurus
I communicate the detection of a new Galactic Wolf-Rayet star (WR60a) in Centaurus. The H- and K-band spectra of WR60a show strong carbon near-infrared emission lines, characteristic of Wolf-Rayet stars of the WC5-7 subtype. Adopting mean absolute magnitude M K and mean intrinsic (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>J</mml:mi><mml:mtext>-</mml:mtext><mml:msub><mml:mi>K</mml:mi><mml:mi>S</mml:mi></mml:msub></mml:math>) and (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>H</mml:mi><mml:mtext>-</mml:mtext><mml:msub><mml:mi>K</mml:mi><mml:mi>S</mml:mi></mml:msub></mml:math>) colours, it was found that WR60a suffers a mean visual extinction of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mn>3.8</mml:mn><mml:mo>±</mml:mo><mml:mn>1.3</mml:mn></mml:math> magnitudes, being located at a probable heliocentric distance of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mn>5.2</mml:mn><mml:mo>±</mml:mo><mml:mn>0.8</mml:mn></mml:math> Kpc, which for the related Galactic longitude (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mtext>l</mml:mtext><mml:mo>=</mml:mo><mml:mn>312</mml:mn></mml:math>) puts this star probably in the Carina-Sagittarius arm at about 5.9 kpc from the Galactic center. I searched for clusters in the vicinity of WR60a and in principle found no previously known clusters in a search radius region of several tens arcminutes. The detection of a well-isolated WR star induced us to seek for some still unknown cluster, somewhere in the vicinity of WR60a. From inspection of 5.8 μ m and 8.0 μ m Spitzer/IRAC GLIMPSE images of the region around the new WR star, strong mid-infrared extended emission at about 13.5 arcmin south-west of WR60a was found. The study of the H-K S colour distribution of point sources associated with the extended emission reveals the presence of a new Galactic cluster candidate probably formed by at least 85 stars.