Multi-wavelength study in the region of IRAS 16571-4029 and 16575-4023 sources

G. Baume ... [et al.].

Serie: Trabajos publicados del IAR ; no. 1541

Resumen: We studied the stellar populations and their associated interstellarmedium structures located in the region of IRAS 16571-4029 and16575-4023 sources, aiming to evaluate their distance and their mainphysical parameters. We focused our attention on the embedded clusterDBS 113 and its associated HII region RCW 116B.

For the study,optical images were obtained using wide band and narrow band filters(ugri and OIII, OIII_C, H_α, H_αC, SIIrespectively) together with infrared (K band) spectra of five stars. inthe region of DBS 113. These data were complemented with availablebibliographic information and photometric multi-band data from severalsurveys at optical (VPHAS+), infrared (2MASS, VVV, WISE) and radio(SGPS, PMN) spectral ranges. Astrometric and photometric data from GAIADR2 in the region were also taken into account.

Our speectroscopicand photometric study allowed to identify near to 20 early type (OB)stars, about 20 objects with infrared excess, and 10 candidates to youngstellar objects in the region of DBS 113. We built their stellar energydistributions ranging from 0.3 to 22 μm. Our data also suggest anabnormal behavior of the reddening law (R_V = 4.0) in theregion of this cluster. Besides, we obtained a correspondingspectrophotometric distance from optical/infrared data which wasconsistent with the distance value computed from GAIA measurements (d [aprox.]2 kpc). This value locates this cluster at the inner side of theSagittarius-Carina Galactic arm and it is different from thetraditionally adopted kinematic distance of 1-1.2 kpc, based on hydrogenrecombination line at millimeter wavelengths. This difference wasexplained by the presence of a hydrogen expanding shell with a centralvelocity relative to the molecular cloud. The new proposed distanceallowed to estimate more precisely the parameters of the HII region RCW116B and to describe the energetic balance among the emission of mostmassive stars, the ionization of the region and the heated dust.Regarding the IRAS 16575-4023 source, we found that the brightest starin this region is a foreground object. We also identified a set of OB-stars candidates with high absorption values (A_V [aprox.] 23 - 26),located behind the molecular cloud AGAL G345.336+01.021.