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Title: GLOBAL VERY LONG BASELINE INTERFEROMETRY OBSERVATIONS OF THE 6.0 GHz HYDROXYL MASERS IN ONSALA 1

Abstract

We present global very long baseline interferometry observations of the first excited-state hydroxyl (OH) masers in the massive star-forming region Onsala 1 (ON 1). The 29 masers detected are nearly all from the 6035 MHz transition and nearly all are identifiable as Zeeman pair components. The 6030 and 6035 MHz masers are coincident with previously published positions of ground-state masers to within a few milliarcseconds, and the magnetic fields deduced from Zeeman splitting are comparable. The 6.0 GHz masers in ON 1 are always found in close spatial association with 1665 MHz OH masers, in contrast to the situation in the massive star-forming region W3(OH), suggesting that extreme high density OH maser sites (excited-state masers with no accompanying ground-state maser, as seen in W3(OH)) are absent from ON 1. The large magnetic field strength among the northern, blueshifted masers is confirmed. The northern masers may trace an outflow or be associated with an exciting source separate from the other masers, or the relative velocities of the northern and southern masers may be indicative of expansion and rotation. High angular resolution observations of nonmasing material will be required in order to understand the complex maser distribution in ON 1.

Authors:
 [1]
  1. MIT Haystack Observatory, Route 40, Westford, MA 01886 (United States)
Publication Date:
OSTI Identifier:
21450885
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 716; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/716/1/106; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; GHZ RANGE 01-100; INTERFEROMETRY; MAGNETIC FIELDS; MASERS; STARS; ZEEMAN EFFECT; AMPLIFIERS; ELECTRONIC EQUIPMENT; EQUIPMENT; FREQUENCY RANGE; GHZ RANGE; MICROWAVE AMPLIFIERS; MICROWAVE EQUIPMENT

Citation Formats

Fish, Vincent L, and Sjouwerman, Lorant O., E-mail: vfish@haystack.mit.ed, E-mail: lsjouwer@nrao.ed. GLOBAL VERY LONG BASELINE INTERFEROMETRY OBSERVATIONS OF THE 6.0 GHz HYDROXYL MASERS IN ONSALA 1. United States: N. p., 2010. Web. doi:10.1088/0004-637X/716/1/106.
Fish, Vincent L, & Sjouwerman, Lorant O., E-mail: vfish@haystack.mit.ed, E-mail: lsjouwer@nrao.ed. GLOBAL VERY LONG BASELINE INTERFEROMETRY OBSERVATIONS OF THE 6.0 GHz HYDROXYL MASERS IN ONSALA 1. United States. https://doi.org/10.1088/0004-637X/716/1/106
Fish, Vincent L, and Sjouwerman, Lorant O., E-mail: vfish@haystack.mit.ed, E-mail: lsjouwer@nrao.ed. 2010. "GLOBAL VERY LONG BASELINE INTERFEROMETRY OBSERVATIONS OF THE 6.0 GHz HYDROXYL MASERS IN ONSALA 1". United States. https://doi.org/10.1088/0004-637X/716/1/106.
@article{osti_21450885,
title = {GLOBAL VERY LONG BASELINE INTERFEROMETRY OBSERVATIONS OF THE 6.0 GHz HYDROXYL MASERS IN ONSALA 1},
author = {Fish, Vincent L and Sjouwerman, Lorant O., E-mail: vfish@haystack.mit.ed, E-mail: lsjouwer@nrao.ed},
abstractNote = {We present global very long baseline interferometry observations of the first excited-state hydroxyl (OH) masers in the massive star-forming region Onsala 1 (ON 1). The 29 masers detected are nearly all from the 6035 MHz transition and nearly all are identifiable as Zeeman pair components. The 6030 and 6035 MHz masers are coincident with previously published positions of ground-state masers to within a few milliarcseconds, and the magnetic fields deduced from Zeeman splitting are comparable. The 6.0 GHz masers in ON 1 are always found in close spatial association with 1665 MHz OH masers, in contrast to the situation in the massive star-forming region W3(OH), suggesting that extreme high density OH maser sites (excited-state masers with no accompanying ground-state maser, as seen in W3(OH)) are absent from ON 1. The large magnetic field strength among the northern, blueshifted masers is confirmed. The northern masers may trace an outflow or be associated with an exciting source separate from the other masers, or the relative velocities of the northern and southern masers may be indicative of expansion and rotation. High angular resolution observations of nonmasing material will be required in order to understand the complex maser distribution in ON 1.},
doi = {10.1088/0004-637X/716/1/106},
url = {https://www.osti.gov/biblio/21450885}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 716,
place = {United States},
year = {Thu Jun 10 00:00:00 EDT 2010},
month = {Thu Jun 10 00:00:00 EDT 2010}
}