The flat oxygen abundance gradient in the extended disk of M83 (2009)
Bresolin, Fabio, Ryan-Weber, Emma, Kennicutt, Robert C., Goddard, Quinton
We have obtained deep multi-object optical spectra of 49 HII regions in the outer disk of the spiral galaxy M83 (=NGC 5236) with the FORS2 spectrograph at the Very Large Telescope. The targets span...
Massey, Philip, Zangari, Amanda M., Morrell, Nidia I., Puls, Joachim, DeGioia-Eastwood, Kathleen, Bresolin, Fabio, ...
In order to better determine the physical properties of hot, massive stars as a function of metallicity, we obtained very high SNR optical spectra of 26 O and early B stars in the Magellanic Clouds....
Luminosity-Metallicity Relation for dIrr Galaxies in the Near-Infrared (2008)
Saviane, Ivo, Ivanov, Valentin D., Held, Enrico V., Alloin, Danielle, Rich, R. Michael, Bresolin, Fabio, ...
(abridged) The present work is a first step to collect homogeneous abundances and near-infrared (NIR) luminosities for a sample of dwarf irregular (dIrr) galaxies, located in nearby groups. The use...
Massive stars in the nuclei and arms of spirals (2008)
Many of the properties of massive stars in external galaxies, such as chemical compositions, mass functions, and ionizing fluxes, can be derived from the study of the associated clouds of ionized...
Szewczyk, Olaf, Pietrzynski, Grzegorz, Gieren, Wolfgang, Storm, Jesper, Walker, Alistair, Rizzi, Luca, ...
We have obtained deep infrared $J$ and $K$ band observations of five fields located in the Large Magellanic Cloud (LMC) bar with the ESO New Technology Telescope equipped with the SOFI infrared...
Extragalaxtic Stellar Astronomy (2007)
Urbaneja, Miguel A., Kudritzki, Rolf Peter, Bresolin, Fabio
Despite their paucity, massive hot stars are real cosmic engines of fundamental importance in shaping our Universe, from its very early stages up to its current appearance. Understanding the physics...
VLT spectroscopy of blue supergiants in IC 1613 (2007)
Bresolin, Fabio, Urbaneja, Miguel A., Gieren, Wolfgang, Pietrzynski, Grzegorz, Kudritzki, Rolf-Peter
We present multi-object spectroscopy of young, massive stars in the Local Group galaxy IC 1613. We provide the spectral classification and a detailed spectral catalog for 54 OBA stars in this galaxy....
Toward a galaxian luminosity-metallicity relation spanning ten magnitudes (2007)
Saviane, Ivo, Bresolin, Fabio, Salzer, John
We describe the two projects by which we are assembling a database of near-IR luminosities and direct oxygen abundances for both high- and low-mass star-forming galaxies in the nearby Universe. This...
I present deep spectroscopy of four HII regions in the inner, metal-rich zone of the spiral galaxy M101 obtained with the LRIS spectrograph at the Keck telescope. From the analysis of the...
Measuring Chemical Abundances in Extragalactic Metal-Rich HII Regions (2006)
The analysis of metal-rich HII regions has a profound impact on the calibration of abundance diagnostics widely used to measure the chemical content of star-forming galaxies, both locally and at high...
Bresolin, Fabio, Pietrzynski, Grzegorz, Urbaneja, Miguel A., Gieren, Wolfgang, Kudritzki, Rolf-Peter, Venn, Kim A.
As part of the Araucaria Project, we present the first spectral catalog of supergiant stars in the Local Group dwarf irregular galaxy WLM. In assigning a spectral classification to these stars we...
Rizzi, Luca, Bresolin, Fabio, Kudritzki, Rolf-Peter, Gieren, Wolfgang, Pietrzynski, Grzegorz
We have used the Advanced Camera for Surveys on board the Hubble Space Telescope to obtain deep photometry of the NGC 300 spiral galaxy in the Sculptor group. The results have been used to derive an...
Bresolin, Fabio, Pietrzynski, Grzegorz, Gieren, Wolfgang, Kudritzki, Rolf-Peter
We have used the Advanced Camera for Surveys aboard the Hubble Space Telescope to obtain F435W, F555W and F814W single-epoch images of six fields in the spiral galaxy NGC 300. Taking advantage of the...
Bresolin, Fabio, Schaerer, Daniel, Delgado, Rosa Gonzalez, Stasinska, Grazyna
We have obtained spectroscopic observations from 3600 Angstrom to 9200 Angstrom with FORS at the Very Large Telescope for approximately 70 H II regions located in the spiral galaxies NGC 1232, NGC...
The near-IR luminosity-metallicity relation of dwarf irregular galaxies (2005)
Saviane, Ivo, Held, Enrico V., Ivanov, Valentin, Alloin, Danielle, Bresolin, Fabio, Rich, R. Michael, ...
We report on the recent developments of our long-term investigation of the near-IR luminosity-metallicity relation for dwarf irregular galaxies in nearby groups. A very well-defined relation is...
Villanova, Sandro, Carraro, Giovanni, Bresolin, Fabio, Ptat, Ferdinando
We report on high resolution spectroscopy of four giant stars in the Galactic old open clusters Berkeley~22 and Berkeley~66 obtained with HIRES at the Keck telescope. We find that...
Massey, Philip, Puls, Joachim, Pauldrach, A. W. A., Bresolin, Fabio, Kudritzki, Rolf P., Simon, Theodore
We analyze the optical and UV spectra of an additional sample of 20 Magellanic Cloud O stars, and draw conclusions from the complete sample of 40 stars. We find (1) The SMC O3-7 dwarfs are about 4000...
Limits on Hubble Constant from the Distance of M100 (2004)
Mould, Jeremy, Huchra, John P., Bresolin, Fabio, Ferrarese, Laura, Ford, Holland C., Freedman, Wendy L., ...
We examine the consequences of a 17 Mpc M100 distance, questioning its consistency with supernova and other distances.
The HST Key Project on the Extragalactic Distance Scale VI. The Cepheids in NGC925 (2004)
Silbermann, N. A., Harding, Paul, Madore, Barry F., Kennicutt, Robert C. Jr., Saha, Abhijit, Stetson, Peter, ...
We report the detection of Cepheid Variable stars in the barred spiral galaxy NGC925, using the Hubble Space Telescope (HST) Wide Field and Planetary Camera 2 (WFPC2). Twelve V (F555W), four I...
The massive star IMF at high metallicity (2004)
The question of the variation of the upper IMF at high metallicity is briefly reviewed. I show recent results suggesting a revision in the definition of `high metallicity' in extragalactic H II...
Rix, Samantha A., Pettini, Max, Leitherer, Claus, Bresolin, Fabio, Kudritzki, Rolf-Peter, Steidel, Charles C.
The chemical composition of high redshift galaxies is an important property which gives clues to their past history and future evolution and yet is difficult to measure with current techniques. In...
Abundances of metal-rich H II regions in M51 (2004)
Bresolin, Fabio, Garnett, Donald R., Kennicutt, Robert C.
We have obtained multi-object spectroscopy of H II regions in the spiral galaxy M51 with the Keck I telescope and the Low Resolution Imaging Spectrometer. For 10 objects we have detected the auroral...
Metal abundances in extremely distant Galactic old open clusters. I. Berkeley 29 and Saurer 1 (2004)
Carraro, Giovanni, Bresolin, Fabio, Villanova, Sandro, Matteucci, Francesca, Patat, Ferdinando, Romaniello, Martino
We report on high resolution spectroscopy of four giant stars in the Galactic old open clusters Berkeley~29 and Saurer~1 obtained with HIRES at the Keck telescope. These two clusters possess the...
Massey, Philip, Bresolin, Fabio, Kudritzki, Rolf P., Puls, Joachim, Pauldrach, A. W. A.
We have obtained HST and ground-based observations of a sample of 20 O-type stars in the LMC and SMC, including six of the hottest massive stars known (subtypes O2-3) in the R136 cluster. In general,...
Bresolin, Fabio, Pietrzynski, Grzegorz, Gieren, Wolfgang, Kudritzki, Rolf-Peter, Przybilla, Norbert, Fouque', Pascal
We present a study of the photometric variability of spectroscopically confirmed supergiants in NGC 300, comprising 28 epochs extending over a period of five months. We find 15 clearly...
Stellar Winds of Hot Massive Stars Nearby and Beyond the Local Group (2003)
Bresolin, Fabio, Kudritzki, Rolf-Peter
Photospheric radiation momentum is efficiently transferred by absorption through metal lines to the gaseous matter in the atmospheres of massive stars, sustaining strong winds and mass loss rates....
Kennicutt, Robert C., Bresolin, Fabio, Garnett, Don R.
(Abridged) We use high S/N spectra of 20 HII regions in the giant spiral galaxy M101 to derive electron temperatures for the HII regions and robust metal abundances over radii R = 0.19-1.25 Ro (6-41...
Quantitative spectral analysis of early B-type supergiants in the Sculptor galaxy NGC 300 (2003)
Urbaneja, Miguel Alejandro, Herrero, Artemio, Bresolin, Fabio, Kudritzki, Rolf-Peter, Gieren, Wolgang, Puls, Joachim
The spectra of two early B-type supergiant stars in the Sculptor spiral galaxy NGC 300 are analysed by means of non-LTE line blanketed unified model atmospheres, aimed at determining their chemical...
Blue Supergiants as a Tool for Extragalactic Distances - Empirical Diagnostics (2003)
Blue supergiant stars can be exceptionally bright objects in the optical, making them prime targets for the determination of extragalactic distances. I describe how their photometric and...
Kudritzki, Rolf P., Bresolin, Fabio, Przybilla, Norbert
Stellar evolution calculations predict the flux-weighted gravity g/Teff^4 and absolute bolometric magnitude of blue supergiants to be strongly correlated. We use medium resolution multi-object...
Bresolin, Fabio, Kudritzki, Rolf-Peter, Najarro, Francisco, Gieren, Wolfgang, Pietrzynski, Grzegorz
We have discovered an Ofpe/WN9 (WN11 following Smith et al.) star in the Sculptor spiral galaxy NGC 300, the first object of this class found outside the Local Group, during a recent spectroscopic...
STIS UV spectroscopy of early B supergiants in M31 (2002)
Bresolin, Fabio, Kudritzki, Rolf-Peter, Lennon, Daniel J., Smartt, Stephen J., Herrero, Artemio, Urbaneja, Miguel A., ...
We analyze STIS spectra in the 1150-1700 Angstrom wavelength range obtained for six early B supergiants in the neighboring galaxy M31. Because of their likely high (nearly solar) abundance, these...
The Wind Momentum-Luminosity relationship: blue supergiants in the spiral galaxy NGC 300 (2002)
Bresolin, Fabio, Kudritzki, Rolf-Peter, Gieren, Wolfgang
We have carried out the wind analysis of six A-type supergiants in NGC 300. The derived Wind Momentum-Luminosity Relationship is compared with that of Galactic and M31 blue supergiants and with...
Bresolin, Fabio, Kennicutt, Robert C.
We present optical spectroscopy of a sample of metal-rich extragalactic HII regions in the spiral galaxies M83, NGC 3351 and NGC 6384, including a number of circumnuclear HII regions (hot spots)....
Spectroscopy of blue supergiants in NGC 300 (2001)
Bresolin, Fabio, Gieren, Wolfgang, Kudritzki, Rolf-Peter, Pietrzynski, Grzegorz, Przybilla, Norbert
We have obtained VLT low-resolution (~5 A) multi-object spectroscopy in the 4,000-5,000 A spectral range of about 70 blue supergiant candidates in the Sculptor Group spiral galaxy NGC 300. We present...
Stellar spectroscopy far beyond the Local Group (2000)
Bresolin, Fabio, Kudritzki, Rolf-Peter, Mendez, Roberto H., Przybilla, Norbert
Multi-object spectroscopic observations of blue supergiants in NGC 3621, a spiral galaxy at a distance of 6.7 Mpc, carried out with the ESO VLT and FORS are presented. We demonstrate the feasibility...
Prosser, Charles F., Kennicutt, Robert C., Bresolin, Fabio, Saha, Abhijit, Sakai, Shoko, ...
We report on the detection of Cepheids and the first distance measurement to the spiral galaxy NGC 1326-A, a member of the Fornax cluster of galaxies. We have employed data obtained with the Wide...
Sakai, Shoko, Ferrarese, Laura, Kennicutt, Robert C., Graham, John A., Silbermann, N. A., Mould, Jeremy R., ...
The distance to NGC 3319 has been determined from Cepheid variable stars as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen and four epochs of...
Gibson, Brad K., Hughes, Shaun M. G., Stetson, Peter B., Freedman, Wendy L., Kennicutt, Robert C., ...
The distance to NGC 4725 has been derived from Cepheid variables, as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen F555W (V) and four F814W (I) epochs...
Ferrarese, Laura, Bresolin, Fabio, Kennicutt, Robert C., Saha, Abhijit, Stetson, Peter B., ...
We report the detection of Cepheids and a new distance to the spiral galaxy NGC 2541, based on data obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope (HST). A...