Highly blueshifted H I gas toward the galactic center

Farhad Yusef-Zadeh*, Anthony Lasenby, Jennifer Marshall

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Güsten & Downes (1981) discovered the presence of -190 km s-1 absorbing H I gas toward the Galactic center. Using the VLA in its most compact hybrid configuration, we were able to image the distribution of this high-negative-velocity H I spectral feature with a spatial and spectral resolution of ≈25″ and 6.2 km s-1, respectively. The blueshifted H I gas is dominated by systematic radial motion as great as -210 km s-1 and is localized to within several arcminutes of the dynamical center of the Galaxy. We show that the H I gas consists of three components which may be physically associated with three radio continuum features. While we have no direct proof of the location of H I gas, we give plausibility arguments in support of one kinematic feature being physically associated with the rotating molecular disk at the Galactic center. In particular, we show a striking column of diffuse H I gas extending for several arcminutes in the direction along the rotation axis of the molecular disk encircling the Galactic center. The H I optical depth distribution indicates that a total of ≈3000 M of neutral material with -211 < VLSR < -160 km s-1 appears to be associated with this feature [assuming the N(H2):N(H I) ratio is 100]. This unusual kinematic feature appears to coexist with two systems of rotationally supported ionized (Sgr A West) and molecular (circumnuclear disk) gas.

Original languageEnglish (US)
Pages (from-to)L27-L30
JournalAstrophysical Journal
Issue number1 PART 2
StatePublished - Jun 10 1993


  • Galaxy: center
  • ISM: atoms
  • ISM: individual (Sagittarius A East, Sagittarius A West, IRS 16)
  • ISM: kinematics and dynamics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Highly blueshifted H I gas toward the galactic center'. Together they form a unique fingerprint.

Cite this