H I zeeman measurements of the magnetic field in sagittarius B2

Richard M. Crutcher; Douglas A. Roberts; David M. Memringer; Thomas H. Troland

H I zeeman measurements of the magnetic field in sagittarius B2

Richard M. Crutcher, Douglas A. Roberts, David M. Memringer, Thomas H. Troland

Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

We have measured the line-of-sight magnetic field toward the Sgr B2 North and Main regions with the VLA by Zeeman mapping of the H i line; B_los ≈ -0.5 mG with spatial variations of about 50%. It is likely that the H I absorption line is produced mainly within the massive molecular envelope surrounding the dense Sgr B2 cores; if so, the B^las we measure is that of the Sgr B2 molecular cloud complex. Maps of the plane-of-sky magnetic field direction from polarized emission of dust have led others to suggest that the present north-south elongation of the Sgr B2 cloud was due to infall along the predominantly east-west oriented magnetic field lines. Our measured magnetic field strength is approximately equal to the critical magnetic field required to support the entire cloud complex against gravitational collapse and thus provides support for this picture. Ambipolar diffusion heating may explain the high gas temperatures in the Sgr B2 cloud.

Original language	English (US)
Pages (from-to)	L79-L82
Journal	Astrophysical Journal
Volume	462
Issue number	2 PART II
State	Published - 1996

Keywords

H II regions
ISM: individual (Sagittarius B2)
ISM: magnetic fields
Radio lines: ISM

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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@article{326b611e5a154d80aba83388b60de8b4,

title = "H I zeeman measurements of the magnetic field in sagittarius B2",

abstract = "We have measured the line-of-sight magnetic field toward the Sgr B2 North and Main regions with the VLA by Zeeman mapping of the H i line; Blos ≈ -0.5 mG with spatial variations of about 50%. It is likely that the H I absorption line is produced mainly within the massive molecular envelope surrounding the dense Sgr B2 cores; if so, the Blas we measure is that of the Sgr B2 molecular cloud complex. Maps of the plane-of-sky magnetic field direction from polarized emission of dust have led others to suggest that the present north-south elongation of the Sgr B2 cloud was due to infall along the predominantly east-west oriented magnetic field lines. Our measured magnetic field strength is approximately equal to the critical magnetic field required to support the entire cloud complex against gravitational collapse and thus provides support for this picture. Ambipolar diffusion heating may explain the high gas temperatures in the Sgr B2 cloud.",

keywords = "H II regions, ISM: individual (Sagittarius B2), ISM: magnetic fields, Radio lines: ISM",

author = "Crutcher, {Richard M.} and Roberts, {Douglas A.} and Memringer, {David M.} and Troland, {Thomas H.}",

note = "Funding Information: 1The Very Large Array is a facility of the National Radio Astronomy Observatory, which is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation. Funding Information: This work has been supported by NSF grants AST 94-19227 and AST 93-20239 to the University of Illinois and AST 94-19220 to the University of Kentucky.",

year = "1996",

language = "English (US)",

volume = "462",

pages = "L79--L82",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "2 PART II",

}

TY - JOUR

T1 - H I zeeman measurements of the magnetic field in sagittarius B2

AU - Crutcher, Richard M.

AU - Roberts, Douglas A.

AU - Memringer, David M.

AU - Troland, Thomas H.

N1 - Funding Information: 1The Very Large Array is a facility of the National Radio Astronomy Observatory, which is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation. Funding Information: This work has been supported by NSF grants AST 94-19227 and AST 93-20239 to the University of Illinois and AST 94-19220 to the University of Kentucky.

PY - 1996

Y1 - 1996

N2 - We have measured the line-of-sight magnetic field toward the Sgr B2 North and Main regions with the VLA by Zeeman mapping of the H i line; Blos ≈ -0.5 mG with spatial variations of about 50%. It is likely that the H I absorption line is produced mainly within the massive molecular envelope surrounding the dense Sgr B2 cores; if so, the Blas we measure is that of the Sgr B2 molecular cloud complex. Maps of the plane-of-sky magnetic field direction from polarized emission of dust have led others to suggest that the present north-south elongation of the Sgr B2 cloud was due to infall along the predominantly east-west oriented magnetic field lines. Our measured magnetic field strength is approximately equal to the critical magnetic field required to support the entire cloud complex against gravitational collapse and thus provides support for this picture. Ambipolar diffusion heating may explain the high gas temperatures in the Sgr B2 cloud.

AB - We have measured the line-of-sight magnetic field toward the Sgr B2 North and Main regions with the VLA by Zeeman mapping of the H i line; Blos ≈ -0.5 mG with spatial variations of about 50%. It is likely that the H I absorption line is produced mainly within the massive molecular envelope surrounding the dense Sgr B2 cores; if so, the Blas we measure is that of the Sgr B2 molecular cloud complex. Maps of the plane-of-sky magnetic field direction from polarized emission of dust have led others to suggest that the present north-south elongation of the Sgr B2 cloud was due to infall along the predominantly east-west oriented magnetic field lines. Our measured magnetic field strength is approximately equal to the critical magnetic field required to support the entire cloud complex against gravitational collapse and thus provides support for this picture. Ambipolar diffusion heating may explain the high gas temperatures in the Sgr B2 cloud.

KW - H II regions

KW - ISM: individual (Sagittarius B2)

KW - ISM: magnetic fields

KW - Radio lines: ISM

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M3 - Article

AN - SCOPUS:15444371197

SN - 0004-637X

VL - 462

SP - L79-L82

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2 PART II

ER -

H I zeeman measurements of the magnetic field in sagittarius B2

Abstract

Keywords

ASJC Scopus subject areas

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