Found 37 talks width keyword star formation

In this talk I will present the first complete 12CO J=3-2 map of M81, observed as part of the Nearby Galaxies Legacy Survey. We have detected nine regions of significant CO emission located at different positions within the spiral arms, and confirmed that the global CO emission in the galaxy is low. Using a new Hα map obtained with the Isaac Newton Telescope and archival data I will discuss a series of topics including the correlation between the molecular gas and star forming regions, the CO (3-2)/(1-0) line ratio, and the amount of hydrogen produced in photo-dissociation regions near the locations where CO J=3-2 was detected.

Massive stars dominate the light output of entire galaxies, with luminosities in excess of 10⁵ L⊙. This makes them powerful probes with which to study a range of astrophysical phenomena. In this talk I will review the recent results of our group, in which we have been able to shed new light on the recent star-forming history of our Galaxy, and the nature of supernova progenitors. I will also discuss our latest project, which is to use massive stars as tracers of extra-galactic star-forming histories out to distances of 10 Mpc and beyond.

CALIFA is the largest IFS survey ever performed up to date. Recently started, it will observe ~600 galaxies in the Local Universe with PPAK at the 3.5m of the Calar Alto Observatory, sampling most of the size of these galaxies and covering the optical wavelength range between 3700-7100 Å, using to spectroscopic setups. The main goal of this survey is to characterize the spatially resolved spectroscopic properties (both the stellar and ionized gas components) of all the population of galaxies at the current cosmological time, in order to understand in detail the how is the final product of the evolution of galaxies. To do so, the sample will cover all the possible galaxies within the color-magnitude diagram, down to M_B ~ -18 mag, from big dry early-types to active fainter late-type galaxies. The main science drivers of the survey is to understand how galaxies evolve within the CM-diagram, understanding the details the process of star formation, metal enrichment, migrations and morphological evolution of galaxies.

Using the k-means cluster analysis algorithm, we carry out an unsupervised classification of all galaxy spectra in the seventh and final Sloan Digital Sky Survey data release (SDSS/DR7). Except for the shift to rest-frame wavelengths and the normalization to the g-band flux, no manipulation is applied to the original spectra. The algorithm guarantees that galaxies with similar spectra belong to the same class. We find that 99% of the galaxies can be assigned to only 17 major classes, with 11 additional minor classes including the remaining 1%. The classification is not unique since many galaxies appear in between classes; however, our rendering of the algorithm overcomes this weakness with a tool to identify borderline galaxies. Each class is characterized by a template spectrum, which is the average of all the spectra of the galaxies in the class. These low-noise template spectra vary smoothly and continuously along a sequence labeled from 0 to 27, from the reddest class to the bluest class. Our Automatic Spectroscopic K-means-based (ASK) classification separates galaxies in colors, with classes characteristic of the red sequence, the blue cloud, as well as the green valley. When red sequence galaxies and green valley galaxies present emission lines, they are characteristic of active galactic nucleus activity. Blue galaxy classes have emission lines corresponding to star formation regions. We find the expected correlation between spectroscopic class and Hubble type, but this relationship exhibits a high intrinsic scatter. Several potential uses of the ASK classification are identified and sketched, including fast determination of physical properties by interpolation, classes as templates in redshift determinations, and target selection in follow-up works (we find classes of Seyfert galaxies, green valley galaxies, as well as a significant number of outliers). The ASK classification is publicly accessible through various Web sites.

We present the new stellar population synthesis models based on the empirical stellar spectral library MILES, which can be regarded nowadays as standard in the field of stellar population studies. The synthetic SEDs cover the whole optical range at resolution 2.3 Å (FWHM). The unprecedented stellar parameter coverage of MILES allowed us to extend our model predictions from intermediate- to very-old age regimes, and the metallicity coverage from super-solar to [M/H] = -2.3. Observed spectra can be studied by means of full spectrum fitting or line-strengths. For the latter we propose a new Line Index System (LIS) to avoid the intrinsic uncertainties associated with the popular Lick/IDS system and provide more appropriate, uniform, spectral resolution. We present a web-page with a suite of on-line tools to facilitate the handling and transformation of the spectra. Online examples with practical applications to work with stellar spectra for a variety of instrumental setups will be shown. Furthermore we will also show examples of how to compute spectra and colors with varying instrumental setup, redshift and velocity dispersion for a suite of Star Formation Histories.

The formation of massive stars is not fully understood. The high luminosity and temperature of massive protostars complicate the accretion mechanism at work in intermediate and low mass young stellar objects. Nonetheless, several scenarios exist to explain the formation of massive stars. In this talk, we will focus on the process of triggered star formation on the borders of H II regions. Due to the feedback effects of OB stars, a layer of molecular material is collected during the expansion of the H II region. Instabilities develop in this layer and give birth to new stars. We will present a detailed study of three Galactic H II regions (RCW79, RCW82 and RCW120). Near-infrared integral field observations have been carried out with SINFONI on the VLT. We will see how they reveal the nature of both the ionizing stars and of the YSOs in the collected layer and how they support the scenario of 'triggered star formation'.

In the local universe, galaxies fall into one of two populations: a star-forming blue cloud and a red sequence lacking star formation. At redshift z ~ 1.5, however, the red sequence has yet to develop. Over the past 9 Gyrs some process has quenched star formation in blue galaxies and caused them to evolve onto the red sequence by fading and/or merging of their stellar populations. While such a transformation may be occurring across the full range of masses, the highest rate of evolution occurs in massive starbursts at the luminous end of the blue cloud. These galaxies are the Luminous Compact Blue Galaxies (LCBGs). In this talk I present preliminary results of a comprehensive multiwavelength survey of LCBGs from z ~ 0 to z ~ 3 we will be carrying out over the next 5 years using several space and ground-based observatories, including the GTC.