VERY LARGE ARRAY H I ZEEMAN OBSERVATIONS OF THE CYGNUS X REGION: DR 22 AND ON 2

Journal Article · Wed Feb 15 04:00:00 EST 2012 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/143/2/32· OSTI ID:22034722

Mayo, E A ^[1]

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1. Department of Biological and Physical Sciences, South Carolina State University, Orangeburg, SC 29117-0001 (United States)

We have used the Very Large Array to study the Zeeman effect in 21 cm H I absorption lines from two star-forming regions in the Cygnus X complex, DR 22 and ON 2. We measure the line-of-sight magnetic field toward these regions, finding B{sub los} = -84 {+-} 11 {mu}G toward the DR 22 H II region and B{sub los} < 50 {mu}G toward each of the two H II regions in ON 2. We interpret these results in terms of two different models. In one model, we assume that the H I Zeeman effect is a measure of magnetic fields in the associated molecular clouds. If so, then the DR 22 molecular cloud is magnetically subcritical, that is, magnetically dominated. The ON 2 molecular clouds are magnetically supercritical. In a second model, we assume that the H I Zeeman effect is a measure of magnetic fields in photon-dominated regions where the gas has been compressed (and the field amplified) by absorption of stellar radiation. We find that this second model, where the measured field strength has been affected by star formation, accounts well for the DR 22 H I Zeeman effect. This same model, however, overpredicts the magnetic field in ON 2. ON 2 may be a region where the magnetic field is energetically insignificant or where the field happens to lie nearly in the plane of the sky.

• OSTI ID: 22034722
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 2 Vol. 143; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ASTRONOMY
ASTROPHYSICS
COSMIC PHOTONS
HYDROGEN
MAGNETIC FIELDS
STAR EVOLUTION
STARS
STELLAR RADIATION
ZEEMAN EFFECT