A VLT VIMOS study of the anomalous BCD Mrk 996: mapping the ionised gas kinematics and abundances

Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

Additional info

Accepted for publication in MNRAS main journal. Minor corrections made and additional discussion. 23 pages, 23 figures

Type

Scientific paper

Abstract

A study of the blue compact dwarf (BCD) galaxy Mrk 996 based on high resolution optical VLT VIMOS integral field unit spectroscopy is presented. Mrk 996 displays multi-component line emission, with most line profiles consisting of a narrow, central Gaussian with an underlying broad component. The broad HI Balmer component splits into two separate broad components inside a 1".5 radius from the nucleus; these are attributed to a two-armed mini-spiral. The rotation curve of Mrk 996 derived from the H\alpha narrow component yields a total mass of 5x10^8 Msol within a radius of 3 kpc. The high excitation energy, high critical density [O III] 4363 and [N II] 5755 lines are only detected from the inner region and exist purely in broad component form, implying unusual excitation conditions. Surface brightness, radial velocity, and FWHM maps for several emission components are presented. A separate physical analysis of the broad and narrow emission line regions is undertaken. We derive an upper limit of 10,000 K for the electron temperature of the narrow line gas, together with an electron density of 170 cm^-3, typical of normal H II regions. For the broad line component, we estimate a temperature of 11,000 K and an electron density of 10^7 cm^-3. The broad line emission regions show a N/H enrichment factor of ~20 relative to the narrow line regions, but no He/H, O/H, S/H, or Ar/H enrichment is inferred. The dominant line excitation mechanism is photoionisation by the ~3000 WR stars and ~150,000 O-type stars estimated to be present in the core. This is indeed a peculiar BCD, with extremely dense zones of gas in the core, through which stellar outflows and possible shock fronts permeate contributing to the excitation of the broad line emission. [Abridged]

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

A VLT VIMOS study of the anomalous BCD Mrk 996: mapping the ionised gas kinematics and abundances 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 A VLT VIMOS study of the anomalous BCD Mrk 996: mapping the ionised gas kinematics and abundances, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A VLT VIMOS study of the anomalous BCD Mrk 996: mapping the ionised gas kinematics and abundances will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-228143

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.