H.alpha interferometric, optical and near IR photometric studies of star forming regions. II. The NGC 7380E/Sh2-142/NGC 7380 complex.
Here we report the results of an uvby-β and JHKLM photometric study of 25 stars in the field direction of the open cluster NGC 7380, and of an Hα interferometric/photographic direct imagery study of the HII and its associated molecular cloud regions Sh2-142 and NGC 7380 E, respectively. The photometric study yielded the following: a) Teff and log g estimates of the program stars, (b) a normal reddening law and uniform extinction towards the region with Aυ/E(B - V) = 3.1±0.1 and Aυ = 2m.0±0m.1, respectively, (c) the result that 16 of the 25 stars observed photometrically are cluster members and the remaining 9 are field stars, (d) and that only 4 of the 16 cluster members studied here have spectral types later than B 1, and (e) similar distance estimates to NGC 7380 by three distinct methods with d = 3.2±0.2 Kpc as its recommended value. From the Hα interferometric imagery of Sh2-142 we find the following: (f) the distribution of the 1100 individual radial velocity points conforming the velocity field of the HII region follow a Gaussian distribution with a mean (LSR) radial velocity of -40.3±0.2 km s-1 and a velocity dispersion of 1σ = 5.1 km s-1, (g) a kinematic distance estimate of dk = 3.3±0.2 Kpc, and (h) a lack of confirmation of the velocity gradient of about 30 km s-1 in the east-west direction of the nebula and the velocity dispersion of 12.5 km s-1 observed with similar techniques by others. The photographic imagery of Sh2-142 in the Hα λ6563Å, [NII]λ6584Å and [SII]λλ6717/6731Å lines reveal (i) the peculiar structure of the nebula composed by several bright arcuated clouds, rims and Hα knots interlaced with local dust lanes, (j) a resemblance between the Hα image and thermal 21 cm radio continuum map in form and size, and (k) the bright knot of about 0.4 pc in diameter is being excited at least partially by the O8V star LSIII 57°89 (nr. 16 here). The current model for the HII/HI/H2 cloud complex is briefly discussed in the context of our observations.
Astronomy and Astrophysics
- Pub Date:
- March 1994
- ISM: individual objects: Sh2-142 - open clusters: individual: NGC 7380 - stars: distances - stars: formation