The Kinematics of Extended Hα Emission in Blue Compact Galaxies

• Blue Compact Galaxies are gas-rich systems with strong star formation and spectra that are dominated by young stars and emission lines. Many are true starburts in the sense that the gas consumption timescales are short. The trigger of the starburst is poorly understood, although mergers are likely to play a role. We have observed a large sample (∼50) of low-z emission-line galaxies with a Fabry-Perot instrument, targeting the H-alpha line at high spectral and spatial resolution. Here, we present a small subsample of objects where we detect emission to large radii in the objects. The near-spherical outer isophotes indicate a central ionising source. In addition, the kinematics of the extended emission is different from that of the central starburst, strengthening the hypothesis of a merging event, triggering the central burst while the surrounding gas is still rather undisturbed. We use additional data from own observations and from the literature to quantify the ionising radiation, as well as to estimate the mass in gas and stars that is compared to the dynamical mass.

Subject headings

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Keyword

Galaxies

Starburst

Kinematics

Extragalactical astronomy

Extragalaktisk astronomi

Publication and Content Type

ref (subject category)

kon (subject category)