HI Galactic Halo Cloud G27.0+6.3 (VLA image)
Description
Since 2002 hundreds of HI (neutral hydrogen) clouds have been discovered with the help of the new unique NRAO instrument -- 100 m Green Bank Telescope (GBT). These clouds are a completely new class of objects presenting a previously unknown phenomenon of the interstellar matter physics. Several brightest of them have been observed with another NRAO instrument, Very Large Array (VLA) which provides better angular resolution. This image shows one of such cloud's (G27.0+6.3) VLA HI column density map. It reveals that the cloud has a "dense core - diffuse envelope" structure. The assymetry of the envelope might also suggest a downward motion. It can be estimated that this cloud is about 7.5 kpc away from us and 850 pc above the Galactic plane. Its size is approximately 20 pc with core size of about 7 pc. This cloud contains 500 solar masses of hydrogen and the density of its core exceeds 20 atoms per cubic cm. The image is a false-color one with blue corresponding to the least and red -- to the most hydrogen density.
The image resolution (taken in VLA D-array) is 1 arcmin, exposure is a few hours. Cloud's peak column density is 3.5x10^+20 cm^-2 and the line's FWHM is 4.8 km/s, as measured from the VLA data. Distance estimated assuming the cloud resides at the tangent point.
Creator
Legacy Astronomical Images
Rights
NRAO/AUI/NSF does not hold full copyright for this image. Contact the archivist for details.
Type
Legacy Astronomical Image
Object Name
HI cloud G27.0+6.3
Photo Credit
Yurii Pidopryhora, NRAO & Ohio University
Investigators
H. Liszt, J. Lockman, M. Rupen, Y. Pidopryhora
Telescope
Very Large Array (VLA)
Observation Date
2004-07-10
Type of Observation
spectral line
Center of Image
RA 18:18:0.000, Dec: -2:15:0.000 (J2000)
Field of View
0.666667 x 0.500000 degrees
Notes
Contact the archivist for a high resolution tif of this image.
Series
Galactic Sources Series
Unit
Galactic Halo Unit
Citation
Legacy Astronomical Images, “HI Galactic Halo Cloud G27.0+6.3 (VLA image),” NRAO/AUI Archives, accessed November 19, 2024, https://www.nrao.edu/archives/items/show/33452.