skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: EXPANDED VERY LARGE ARRAY CONTINUUM OBSERVATIONS TOWARD HOT MOLECULAR CORE CANDIDATES

Abstract

We have used the Expanded Very Large Array (EVLA) with two 1 GHz wide bands to obtain K-band (1.3 cm) continuum observations toward the following five hot molecular core candidates: IRAS 18151 - 1208, IRAS 18182 - 1433, IRAS 18345 - 0641, IRAS 18470 - 0044, and IRAS 19012 + 0536. The sources were selected from the 2002 list of Sridharan et al. and are characterized by high FIR luminosity, dense molecular and dust condensations, massive large-scale CO flows, and the absence of strong cm continuum emission. These properties are indicative of massive star-forming regions in an evolutionary phase prior to ultra- or hypercompact H II regions. We detect a total of 10 individual 1.3 cm continuum sources toward this sample, and derive in-band spectral indices between 19.3 and 25.5 GHz consistent with thermal free-free emission, for all sources except component A in IRAS 18182 - 1433, which has a negative spectral index indicative of synchrotron emission. We suggest that in most cases the 1.3 cm sources are due to shock-induced ionization, rather than direct photoionization by massive objects. The momentum rate present in these ionized flows is sufficient to drive the large-scale molecular flows. We discuss a number ofmore » morphological features supporting this hypothesis. The present observations demonstrate that the EVLA has sufficient sensitivity to study the regions near very young massive stars in the cm continuum.« less

Authors:
 [1]; ; ;  [2];  [3]; ;  [4];  [5];  [6]
  1. Physics Department, New Mexico Tech, 801 Leroy Pl., Socorro, NM 87801 (United States)
  2. Centro de RadioastronomIa y Astrofisica, P.O. Box 3-72 Universidad Nacional Autonoma de Mexico, Morelia 58090 (Mexico)
  3. School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001 (Australia)
  4. Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany)
  5. Physics Department, Western Illinois University, 1 University Circle, Macomb, IL 61455 (United States)
  6. INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze (Italy)
Publication Date:
OSTI Identifier:
21565450
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 739; Journal Issue: 1; Other Information: DOI: 10.1088/2041-8205/739/1/L17; Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; DUSTS; EMISSION; LUMINOSITY; STAR EVOLUTION; STARS; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; EVOLUTION; OPTICAL PROPERTIES; OXIDES; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES

Citation Formats

Hofner, P., Kurtz, S., Loinard, L., RodrIguez, L. F., Ellingsen, S. P., Menten, K. M., Wyrowski, F., Araya, E. D., and Cesaroni, R. EXPANDED VERY LARGE ARRAY CONTINUUM OBSERVATIONS TOWARD HOT MOLECULAR CORE CANDIDATES. United States: N. p., 2011. Web. doi:10.1088/2041-8205/739/1/L17.
Hofner, P., Kurtz, S., Loinard, L., RodrIguez, L. F., Ellingsen, S. P., Menten, K. M., Wyrowski, F., Araya, E. D., & Cesaroni, R. EXPANDED VERY LARGE ARRAY CONTINUUM OBSERVATIONS TOWARD HOT MOLECULAR CORE CANDIDATES. United States. doi:10.1088/2041-8205/739/1/L17.
Hofner, P., Kurtz, S., Loinard, L., RodrIguez, L. F., Ellingsen, S. P., Menten, K. M., Wyrowski, F., Araya, E. D., and Cesaroni, R. Tue . "EXPANDED VERY LARGE ARRAY CONTINUUM OBSERVATIONS TOWARD HOT MOLECULAR CORE CANDIDATES". United States. doi:10.1088/2041-8205/739/1/L17.
@article{osti_21565450,
title = {EXPANDED VERY LARGE ARRAY CONTINUUM OBSERVATIONS TOWARD HOT MOLECULAR CORE CANDIDATES},
author = {Hofner, P. and Kurtz, S. and Loinard, L. and RodrIguez, L. F. and Ellingsen, S. P. and Menten, K. M. and Wyrowski, F. and Araya, E. D. and Cesaroni, R.},
abstractNote = {We have used the Expanded Very Large Array (EVLA) with two 1 GHz wide bands to obtain K-band (1.3 cm) continuum observations toward the following five hot molecular core candidates: IRAS 18151 - 1208, IRAS 18182 - 1433, IRAS 18345 - 0641, IRAS 18470 - 0044, and IRAS 19012 + 0536. The sources were selected from the 2002 list of Sridharan et al. and are characterized by high FIR luminosity, dense molecular and dust condensations, massive large-scale CO flows, and the absence of strong cm continuum emission. These properties are indicative of massive star-forming regions in an evolutionary phase prior to ultra- or hypercompact H II regions. We detect a total of 10 individual 1.3 cm continuum sources toward this sample, and derive in-band spectral indices between 19.3 and 25.5 GHz consistent with thermal free-free emission, for all sources except component A in IRAS 18182 - 1433, which has a negative spectral index indicative of synchrotron emission. We suggest that in most cases the 1.3 cm sources are due to shock-induced ionization, rather than direct photoionization by massive objects. The momentum rate present in these ionized flows is sufficient to drive the large-scale molecular flows. We discuss a number of morphological features supporting this hypothesis. The present observations demonstrate that the EVLA has sufficient sensitivity to study the regions near very young massive stars in the cm continuum.},
doi = {10.1088/2041-8205/739/1/L17},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 1,
volume = 739,
place = {United States},
year = {2011},
month = {9}
}