We report the results of a survey of radio continuum emission of Galactic Wolf-Rayet stars north of δ = −46 • . The observations were obtained at 8.46 GHz (3.6 cm) using the Very Large Array (VLA), with an angular resolution of ∼ 6 ′′ ×9 ′′ and typical rms noise of ∼ 0.04 mJy beam −1 . Our survey of 34 WR stars resulted in 15 definite and 5 probable detections, 13 of these for the first time at radio wavelengths. All detections are unresolved (θ 5 ′′ ). Time variations in flux are confirmed in the cases of WR 98a, WR 104, WR 105, and WR 125. WR 79a and WR 89 are also variable in flux and we suspect they are also non-thermal emitters. Thus, of our sample 20 -30 % of the detected stars are non-thermal emiters. Average mass loss rates determinations obtained excluding definite and suspected non-thermal cases give similar values for

The environment of the Wolf-Rayet (WR) star WR 130 has been studied using the 21 cm H I line and radio continuum data at 408 and 1420 MHz obtained with the Dominion Radio Astrophysical Observatory (DRAO) Synthesis Telescope. In addition, the H110a recombination line and 21 cm H I line were observed using the Very Large Array in the DnC and D conÐgurations. The Sharpless H II region, Sh 98 (size D15@), and two OB stars are observed near the Wolf-Rayet star position. An extended ring-shaped structure (G68.1]1.1) of size D20@ is observed in the radio continuum and infrared data. Of four compact radio sources seen superposed on the ring, one is an H II region of size D3@ (G68.14]0.92), while the others are probably extragalactic. The spectral index of G68.1]1.1 is a \ 0.0^0.1. (S l P la) The thermal nature of G68.1]1.1 is conÐrmed by an analysis of the correlation between the brightness temperature at 21 cm and the brightness at 60 km, as observed with IRAS. The DRAO H I data show an H I bubble in the velocity range [12 to 1 km s~1. The most striking characteristic of the H I cavity is the excellent correlation with the radio continuum ring. The WR star is not at the center of the ring, but in the dense border to the east. This eccentric position can be explained by a combination of a high spatial velocity for the star and projection e †ects. The possible contribution of the OB stars present in the area is also considered. From our H110a observations, together with other recombination lines observed in the area, we deduce a distance of 12 kpc for the compact H II region G68.14]0.92 and 5 kpc for G68.1]1.1. We conclude that G68.1]1.1 is the radio counterpart of the optical H II region Sh 98, while G68.14]0.92 is a chance superposition of a much more distant source. The ionized mass of the ring is estimated at D3000 and the rms electron density at D3 cm~3, assuming a homogene-M _ ous distribution. A missing H I mass of 500 is obtained for the cavity and an excess H I mass of M _ 1500 for the shell.

Abstract.A sample of OB stars (eleven Of, one O and one B supergiant) has been surveyed with the Australia Telescope Compact Array at 4.8 and 8.64 GHz with a resolution of ∼2 -4 . Five stars were detected; three of them have negative spectral indices, consistent with non-thermal emission, and two have positive indices. The thermal radiation from HD 150135 and HD 163181 can be explained as coming from an optically thick ionized stellar wind. The non-thermal radiation from CD-47• 4551, HD 124314 and HD 150136 possibly comes from strong shocks in the wind itself and/or in the wind colliding region if the stars have a massive early-type companion. The percentage of non-thermal emitters among detected O stars has increased up to ∼50%. The Of star HD 124314 clearly shows flux density variations. Mass loss rates (or upper limits) were derived for all the observed stars and the results compared with non-radio measurements and theoretical predictions.

We have examined the interstellar medium in the vicinity of massive stars belonging to the Per OBI association based on neutral hydrogen 21 cm observations obtained with the 100 m radio telescope at Effelsberg (HPBW = 814) and complementary data from the Leiden-Dwingeloo H i Survey (HPBW = 36'). The higher angular resolution H i observations allowed us to discover probable wind blown bubbles related to four massive stars in the association, namely, HD 14442 [O5n(f)p], HD 14947 [O5If+], HD 13022 [O9.5II-III((n))J, and HD 13338 [O9.5V], while the detection of a wind-blown bubble associated with HD 16691 [O5If+] is less conclusive. A clear H i shell coincident in position with two Bl III stars (HD 15233 and Hilt 311) was also detected. Some of these features also have infra red and/or molecular counterparts. The energetics of the structures related to each massive star is analyzed. The new H i interstellar bubbles appear to be similar to the ones found surrounding Wolf-Rayet stars and other Of stars. The large-scale maps obtained using the lower angular resolution H i data show that most of the early-type stars belonging to Per OBI are placed in a region of low H i emission. The association could have blown a H i shell of about 350 x 550 pc in size. This large H i shell has an infrared counterpart.