Showing papers by "A. Gil de Paz published in 2000"
TL;DR: In this paper, the authors presented new near-infrared J and K imaging data for 67 galaxies from the UCM survey used in the determination of the SFR density of the local Universe by Gallego et al.
Abstract: We present new near-infrared J and K imaging data for 67 galaxies from the Universidad Complutense de Madrid (UCM) survey used in the determination of the SFR density of the local Universe by Gallego et al. This is a sample of local star-forming galaxies with redshift lower than 0.045, and they constitute a representative subsample of the galaxies in the complete UCM survey. From the new data, complemented with our own Gunn−r images and long-slit optical spectroscopy, we have measured integrated K-band luminosities, r−J and J−K colours, and Hα luminosities and equivalent widths. Using a maximum likelihood estimator and a complete set of evolutionary synthesis models, these observations allow us to estimate the strength of the current (or most recent) burst of star formation, its age, the star formation rate and the total stellar mass of the galaxies. An average galaxy in the sample has a stellar mass of 5×10^10 M_⊙ and is undergoing (or has recently completed) a burst of star formation involving about 2 per cent of its total stellar mass. We identify two separate classes of star-forming galaxies in the UCM sample: low-luminosity, high-excitation galaxies (HII-like) and relatively luminous spiral galaxies (starburst disk−like). The former show higher specific star formation rates (SFRs per unit mass) and burst strengths, and lower stellar masses than the latter. With regard to their specific star formation rates, the UCM galaxies are intermediate objects between normal quiescent spirals and the most extreme H II galaxies.
32 citations
TL;DR: In this article, the authors presented new near-infrared J and K imaging data for 67 galaxies from the UCM survey used to determine the SFR density of the local universe by Gallego et al.
Abstract: We present new near-infrared J and K imaging data for 67 galaxies from the Universidad Complutense de Madrid survey used to determine the SFR density of the local universe by Gallego et al. (1995). This is a sample of local star-forming galaxies with redshift lower than 0.045, and they constitute a representative subsample of the galaxies in the complete UCM survey. From the new data, complemented with our own Gunn-r images and long-slit optical spectroscopy, we have measured integrated K-band luminosities, r-J and J-K colours, and Halpha luminosities and equivalent widths. Using a maximum likelihood estimator and a complete set of evolutionary synthesis models, these observations have allowed us to estimate the strength of the current (or most recent) burst of star formation, its age, the star-formation rate and the total stellar mass of the galaxies. An average galaxy in the sample has a stellar mass of 5E10 Msun and is undergoing (or recently completed) a burst of star formation involving about 2 per cent of its total stellar mass. We have identified two separate classes of star-forming galaxies in the UCM sample: low luminosity, high excitation galaxies (HII-like) and relatively luminous spirals galaxies (starburst disk-like). The former show higher specific star formation rates (SFR per unit mass) and burst strengths, and lower stellar masses than the latter. With regard to their specific star formation rates, the UCM galaxies are intermediate objects between normal quiescent spirals and the most extreme HII galaxies.
28 citations
TL;DR: In this paper, the authors presented optical near-infrared colors and emission-line fluxes for the currently star-forming regions, intermediate aged starburst and underlying stellar population.
Abstract: We have obtained optical (BVR, [O III]ƛ 5007 A and H_α), near infrared (JHK) imaging and long-slit optical spectroscopy for the Blue Compact Dwarf galaxy Mrk 86 (NGC 2537). In this paper, the first of two, we present optical-near-infrared colors and emission-line fluxes for the currently star-forming regions, intermediate aged starburst and underlying stellar population. We also describe the evolutionary synthesis models used in Paper II. The R and H_α luminosity distributions of the galaxy star-forming regions show maxima at M-R = -9.5^m and L_H_α = 10^37.3 ergs^-l. The underlying stellar population shows an exponential surface brigthness profile with central value, μ_E,0 = 21.5 mag arcsec^-2, and scale, α=0.88 kpc, both measured in the R-band image. In the galaxy outer regions, dominated by this component, no significant color gradients are observed. Finally, a complete set of evolutionary synthesis models have been developed, covering a wide range in metallicity, 1/50 Z_⨀< Z < 2 Z_⨀, and burst strength, 1-10^-4. These models include nebular continuum and recombination and forbidden-line emission.
25 citations
TL;DR: In this article, the authors presented optical-near-infrared colors and emission-line fluxes for the currently star-forming regions, intemediate aged starburst and underlying stellar population.
Abstract: We have obtained optical (BVR, [OIII]5007 and Halpha), near infrared (JHK) imaging and long-slit optical spectroscopy for the Blue Compact Dwarf galaxy Mrk86 (NGC2537). In this paper, the first of two, we present optical-near- infrared colors and emission-line fluxes for the currently star-forming regions, intemediate aged starburst and underlying stellar population. We also describe the evolutionary synthesis models used in Paper II. The R and Halpha luminosity distributions of the galaxy star-forming regions show maxima at M_R=-9.5 and L_Halpha=10^37.3 erg s^-1. The underlying stellar population shows an exponential surface brigthness profile with central value, mu_E,0=21.5 mag arcsec^-2, and scale, alpha=0.88 kpc, both measured in the R-band image. In the galaxy outer regions, dominated by this component, no significant color gradients are observed. Finally, a set of evolutionary synthesis models have been developed, covering a wide range in metallicity and burst strength.
22 citations
Posted Content•
TL;DR: In this article, the main properties of the stellar populations in the Blue Compact Dwarf galaxy Mrk86 were derived using the combination of Monte Carlo simulations, a maximum likelihood estimator and Cluster and Principal Component Analysis.
Abstract: In this paper, continuation of Gil de Paz et al. (Paper I), we derive the main properties of the stellar populations in the Blue Compact Dwarf galaxy Mrk86. Ages, stellar masses, metallicites and burst strengths have been obtained using the combination of Monte Carlo simulations, a maximum likelihood estimator and Cluster and Principal Component Analysis. The three stellar populations detected show well defined properties. We have studied the underlying stellar population, which shows an age between 5-13 Gyr and no significant color gradients. The intermediate aged (30 Myr old) central starburst show a very low dust extinction with high burst strength and high stellar mass content (9 10^6 M_sun). Finally, the properties of 46 low-metallicity star-forming regions were also studied. The properties derived suggest that the most recent star-forming activity in Mrk86 was triggered by the evolution of a superbubble originated at the central starburst by the energy deposition of stellar winds and supernova explosions. Finally, different mechanisms for the star formation triggering in this massive central starburst are studied, including the merging with a low mass companion and the interaction with UGC4278.
1 citations
01 Jan 2000
TL;DR: In this article, the main properties of the stellar populations in the Blue Compact Dwarf galaxy Mrk 86 were derived using the combination of Monte Carlo simulations, a maximum likelier- hood estimator and Cluster and Principal Component Analysis.
Abstract: In this paper, continuation of Gil de Paz et al. (Pa- per I), we derive the main properties of the stellar populations in the Blue Compact Dwarf galaxy Mrk 86. Ages, stellar masses, metallicites and burst strengths have been obtained using the combination of Monte Carlo simulations, a maximum likeli- hood estimator and Cluster and Principal Component Analysis. The three stellar populations detected show well defined prop- erties. We have studied the underlying stellar population, which shows an age between 5-13 Gyr and no significant color gradi- ents. The intermediate aged (30 Myr old) central starburst show a very low dust extinction with high burst strength and high stellar mass content (910 6 M). Finally, the properties of 46 low-metallicity (1/10 Z) star-forming regions were also studied. The properties derived suggest that the most recent star- forming activity in Mrk 86 was triggered by the evolution of a superbubble originated at the central starburst by the energy deposition of stellar winds and supernova explosions. This su- perbubble produced the blowout of a fraction of the interstellar medium at distances of about 1 kpc with high gas surface den- sities, leading to the activation of the star formation. Finally, different mechanisms for the star formation trigger- ing in this massive central starburst are studied, including the merging with a low mass companion and the interaction with UGC 4278. We have assumed a distance to Mrk 86 of 6.9 Mpc.