Water Masers and Evidence of a Circumnuclear Disk in NGC 4258?

Details Water Masers and Evidence of a Circumnuclear Disk in NGC 4258? Water Masers and Evidence of a Circumnuclear Disk in NGC 4258?

May 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994aas...184.6404g&link_type=abstract

American Astronomical Society, 184th AAS Meeting, #64.04; Bulletin of the American Astronomical Society, Vol. 26, p.966

Other

1

Scientific paper

We present the first VLBI synthesis map of the luminous H_2O maser in the nucleus of NGC 4258, for epoch 1984.77. The maser spectral features were distributed on an East--West arc in the sky, subtending about 250 microarcseconds (mu as) in angle (2.6*E(16) cm). The distribution was not resolved in the North-South direction (<< 500 mu as). The Doppler velocity of the maser emission changes with position along the arc with an essentially constant gradient of 0.0391+/-0.0002 km s(-1) AU(-1) . The most redshifted emission lie farthest to the East for these observations. This source is at least an order of magnitude more compact than the other extremely luminous extragalactic H_2O maser that has been mapped with VLBI techniques (i.e., NGC 3079). If the angular distribution of the maser emission traces an underlying gravitationally bound rotating disk then the observed range of velocities and angular extent imply an enclosed mass of ~ 700 M_sun. The extraordinary luminosity of the maser is not consistent with what is seen in regions of star formation within our galaxy. We suggest that the H_2O maser emission from the nucleus NGC 4258 may originate in a circumnuclear molecular ``ring,'' stimulated by a background, high brightness temperature radio continuum source known to exist in the nucleus or by H_2O maser emission from the back side of the circumnuclear ring. The VLBI observations reported here provide important clues and constraints on the proposed model. High velocity H_2O maser emission (+/-800 km s(-1) ) has recently been discovered in this galaxy. VLBI observations (Nakai et al.) show that these are spatially coincident with the low velocity components to within about 2 pc.

Affiliated with

Also associated with

No associations

Rating

Water Masers and Evidence of a Circumnuclear Disk in NGC 4258? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Water Masers and Evidence of a Circumnuclear Disk in NGC 4258?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water Masers and Evidence of a Circumnuclear Disk in NGC 4258? will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-884094