The Hydrogen Clouds in the Galactic Halo

Lockman, Felix J.

doi:10.1017/s0074180900197281

Cited by 3 publications

(5 citation statements)

References 23 publications

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“…The clouds described here show a resemblance in properties to the H I clouds several hundred parsec from the mid plane described by Lockman (2002Lockman ( , 2003; Lockman & Pidopryhora (2005). The masses, velocities, and line widths are similar between the samples.…”

Section: Discussionsupporting

confidence: 60%

“…Random motions can carry individual clouds to 'forbidden' velocities V LSR > V tan . For example, some halo clouds have random velocities in excess of 40 km s −1 (Lockman 2002(Lockman , 2003.…”

Section: Data Set and Search Parametersmentioning

confidence: 99%

“…A median halo cloud from a sample of 40 located at a median distance from the plane of z = −940 pc has an H I mass of 50 M ⊙ , a diameter of a few tens of parsecs, a column density of a few times 10 19 cm −2 , and average H I density of a few tenths cm −3 . The clouds in the halo follow Galactic rotation, but with a fairly large cloud-to-cloud velocity dispersion of several tens of km s −1 (Lockman 2002(Lockman , 2003.…”

Section: Introductionmentioning

confidence: 99%

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Compact HiClouds at High Forbidden Velocities in the Inner Galaxy

Stil

Lockman

Taylor

et al. 2006

ApJ

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The VLA Galactic Plane Survey (VGPS) of the first Galactic quadrant was searched for H I emission with velocities well above the maximum velocity allowed by Galactic rotation. A sample of 17 small fast-moving clouds was identified. The distribution of the ensemble of clouds in longitude and velocity indicates that the clouds are part of the Galactic disk, despite their large forbidden velocity. The median angular diameter of the clouds detected in the VGPS is 3. ′ 4. These clouds would not be noticed in previous low resolution surveys because of strong beam dilution. Assuming each cloud is located at the tangent point, a median cloud has a diameter of 10 pc, H I mass of 60 M ⊙ , and a velocity more than 25 km s −1 beyond the local terminal velocity derived from 12 CO observations. Three clouds

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Section: Discussionsupporting

confidence: 60%

Section: Data Set and Search Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Compact HiClouds at High Forbidden Velocities in the Inner Galaxy

Stil

Lockman

Taylor

et al. 2006

ApJ

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“…The spur is observed at much higher forbidden velocities. Also, the velocity gradient of the spur and the width of the H i line profile in the spur do not match the narrow line widths observed in these halo clouds (Lockman 2002(Lockman , 2004.…”

Section: Kinematics and Mass Of The Spurmentioning

confidence: 79%

HiDistribution and Kinematics of UGCA 86

Stil¹,

Gray²,

Harnett³

2005

ApJ

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We present 21-cm H i line and 408 MHz and 1.4 GHz continuum observations of the Magellanic dwarf galaxy UGCA 86, made with the DRAO synthesis telescope. UGCA 86 is detected in the continuum at both frequencies, with 408 MHz flux density S 408 = 120 ± 30 mJy and 1.4 GHz flux density S 1400 = 79 ± 3 mJy. The H i structure of UGCA 86 is complex, with two separate components: a rotating disk and a highly elongated spur that is kinematically disjunct from the disk. The H i disk is centered on the optical galaxy with similar axial ratio and orientation of the major axis. An area of the disk with a peculiar velocity of ∼ 25 km s −1 relative to the regular rotation of the disk is found on the southern side, where most of the star formation is concentrated. The spur is seen along the minor axis of UGCA 86 and overlaps in part with the disk. Towards the

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“…Do the ionized and neutral phases cycle from one to the other? Cox and Helenius (2003) and Lockman (2004), for example, have suggested that portions of the ionized medium may condense into neutral clouds. However, to date there have been no observational studies of the H + -H 0 connection.…”

Section: Warm Ionized and Neutral Gasmentioning

confidence: 99%

The warm ionized medium in spiral galaxies

et al. 2009

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This article reviews observations and models of the diffuse ionized gas that permeates the disk and halo of our Galaxy and others. It was inspired by a series of invited talks presented during an afternoon scientific session of the 65th birthday celebration for Professor Carl Heiles held at Arecibo Observatory in August 2004. This review is in recognition of Carl's long standing interest in and advocacy for studies of the ionized as well as the neutral components of the interstellar medium.Comment: 29 pages, 19 figures; accepted by Reviews of Modern Physic

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The Hydrogen Clouds in the Galactic Halo

Cited by 3 publications

References 23 publications

Compact HiClouds at High Forbidden Velocities in the Inner Galaxy

Compact HiClouds at High Forbidden Velocities in the Inner Galaxy

HiDistribution and Kinematics of UGCA 86

The warm ionized medium in spiral galaxies

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