Deep VLA Images of the HH 124 IRS Radio Cluster and Its Surroundings, and a New Determination of the Distance to NGC 2264
Abstract
We present new deep (σ ~ 6 μJy) radio images of the HH 124 IRS radio cluster at 4.8 and 7.5 GHz. We detect a total of 50 radio sources, most of them compact. Variability and spectral indices were analyzed in order to determine the nature of the sources and of their radio emission. A proper motion study was also performed for several of these radio sources using previously reported radio observations. Our analysis shows that 11 radio sources can be associated with Galactic objects, most of them probably young stars. Interestingly, 8 of these sources are in an area less than 1 arcmin2 in size. The importance of such compact clusters resides in that all of its members can be observed in a single pointing with most telescopes and are, therefore, ideal for multi-wavelength studies of variability. Another 4 of the detected sources are clearly extragalactic. Finally, we propose from statistical arguments that out of the remaining sources, about 10 are Galactic, but our study does not allow us to identify which of the sources fall in that specific category. The relatively large proper motions observed for the sources in HH 124 IRS suggest that this region is located at about 400 pc from the Sun. This is significantly smaller than the ~800-900 pc distance usually assigned to the nearby open cluster NGC 2264 with which HH 124 is thought to be associated. However, a reanalysis of the Hipparcos parallaxes for members of NGC 2264, a convergent point approach, and a kinematic analysis all argue in favor of a distance of the order of 400 pc for NGC 2264 as well.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2014
- DOI:
- 10.1088/0004-637X/788/2/162
- arXiv:
- arXiv:1404.7543
- Bibcode:
- 2014ApJ...788..162D
- Keywords:
-
- astrometry;
- ISM: individual objects: HH 124IRS;
- radiation mechanisms: non-thermal;
- radiation mechanisms: thermal;
- radio continuum: stars;
- techniques: interferometric;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 24 pages, 6 figures, 6 tables. Accepted for publication in ApJ