Shock waves push the gas, which sets off the starburst activity.
Searches for the expected supernovae have had mixed results.
PSBs are traditionally identified by their spectral features, usually the strong absorption lines associated with the A-type stars that dominate these galaxies’ starlight. Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. CONSTRAINTS ON THE LOW-MASS IMF IN YOUNG SUPER-STAR CLUSTERS IN STARBURST GALAXIES by Julia Jennifer Greissl BY: = Creative Commons Attribution-No Derivative Works 3.0 United States License.
Star formation yields an IMF with high mass stars dominating the luminosity These yield, directly or indirectly, to a wide range of emission See Kennicutt and Evans ARAA 2012 for excellent review: UV flux : high mass stars dominate UV luminosity visible if non-dusty . PSB galaxies have a star formation history dominated by a burst in the exact age range when TP-AGB stars are expected to have the strongest impact, i.e. It looks like a galaxy with more HII regions than normal. Comparison between observations and models of evolving stellar populations helps understand the star formation process, triggering mechanisms, influence of the environment, the chemical history, and processes in the interstellar gas. High mass galaxies passive red spheroids dominated by old stars Low mass galaxies star forming, blue disk galaxies What produces this bimodality?
Astronomers know that starburst galaxies are often involved in mergers that mingle stars and gas.
Stellar evolutionary models lead us to expect galaxies that are fairly blue (but rapidly reddening with time unless the burst was of large relative mass amplitude), whose spectral features are dominated by either supergiants or the upper main sequennce. Starburst galaxies are galaxies where high rates of star formation has occurred very quickly. Starburst galaxies are otherwise normal galaxies that are undergoing an intense episode of star formation.
Shock waves push the gas, which sets off the starburst activity. Hierarchical models) Why are there few low mass passive galaxies ?
Even if the mass of stars and remnants formed during the starburst were 20% of the dynamical mass, the starburst population itself would have an MIL of only 0.003. Starburst galaxies have calculated star-forming rates as high as hundreds of solar masses per year (exhaustion timescales of order 10 8 years), and correspondingly high expected supoernova rates. The radiative properties of starburst galaxies are determined by their massive stellar content. 1: Relation between the dura- tion of a starburst … STARBURSTS IN INTERACTING GALAXIES: OBSERVATIONS AND MODELS Konrad Bernliihr Max-Planck-Institut fiir Astronomie Kiinigstuhl 17 D-6900 Heidelberg, F.R.Germany 1 Introduction Starbursts have been a puzzling field of research for more than a decade.decade. Although the stellar absorption spectrum is present, the line spectrum is dominated by HII regions rather than stars.
Astronomers know that starburst galaxies are often involved in mergers that mingle stars and gas. The spectra have been extracted with an optimal algorithm and co-added to produce spectra with the best possible signal-to-noise ratio. In what part of the EM spectrum do Starburst galaxies emit most of their radiation? Near-infrared images, spectra, and optical rotation curves were presented in Smith et al.
As the A-type spectra fades, the last Balmer line to disappear is H 4101
In fact, Figure 5 is the spectrum of a starburst galaxy.
Comparison between observations and models of evolving stellar populations helps understand the star formation process, triggering mechanisms, influence of the environment, the chemical history, and processes in the interstellar gas. Within 10 Mpc, 25% of high mass star formation occurs in just four starburst galaxies (Heckman, 1998).. Starburst galaxies are galaxies where high rates of star formation has occurred very quickly.
This SDSS example has red old spectrum, no emission lines, but strong Balmer absorption lines: [o-link] .
Stars evolve - and so do galaxies.
In this paper, the authors investigate post-starburst galaxies (PSBs, or E+A galaxies as described in the astrobites galaxy classification guide), which are galaxies that have only recently stopped forming stars.