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The identification of strong gravitational lenses in large surveys has historically been a rather time consuming exercise. Early data from the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) demonstrate that lenses can…

Cosmology and Nongalactic Astrophysics · Physics 2012-06-22 Jo Short , Elizabeth Pearson , Peter Coles , Steve Eales

M dwarfs are important targets in the search for Earth-like exoplanets due to their small masses and low luminosities. Several ongoing and upcoming space missions are targeting M dwarfs for this reason, and the ESA PLATO mission is one of…

Here we describe some of our latest results from measuring detailed abundances in Local Group dwarf galaxies with VLT. Combining spectroscopic abundances with Colour-Magnitude diagrams allows the effective measurement of detailed chemical…

Astrophysics · Physics 2007-05-23 Eline Tolstoy , Kim Venn

Current and future continuum surveys being undertaken by the new generation of radio telescopes are now poised to address many important science questions, ranging from the earliest galaxies, to the physics of nearby AGN, as well as…

Instrumentation and Methods for Astrophysics · Physics 2016-04-25 Jeremy J. Harwood , Raffaella Morganti

We describe a new algorithm for the "perfect" extraction of one-dimensional spectra from two-dimensional (2D) digital images of optical fiber spectrographs, based on accurate 2D forward modeling of the raw pixel data. The algorithm is…

Instrumentation and Methods for Astrophysics · Physics 2015-05-14 Adam S. Bolton , David J. Schlegel

We review the field of abundance determinations of elements in cool stars, with special interest paid to determinations based on analyses of high-resolution, 1-5 micron spectra. We discuss the current status, problems, and challenges of…

Astrophysics · Physics 2009-11-10 N. Ryde , B. Gustafsson , K. Eriksson , R. Wahlin

While emission-line flux ratio diagnostics are the most common technique for identifying active galactic nuclei (AGNs) in optical spectra, applying this approach to single fiber spectra of galaxies can omit entire subpopulations of AGNs.…

(Abridged) We describe a new method to extract spectra of stars from observations of crowded stellar fields with integral field spectroscopy (IFS). Our approach extends the well-established concept of crowded field photometry in images into…

Instrumentation and Methods for Astrophysics · Physics 2015-06-12 Sebastian Kamann , Lutz Wisotzki , Martin M. Roth

We describe a self-consistent spectrum analysis technique employing non-LTE line formation, which allows precise atmospheric parameters of massive stars to be derived: 1sigma-uncertainties as low as ~1% in effective temperature and…

Solar and Stellar Astrophysics · Physics 2015-03-17 Maria-Fernanda Nieva , Norbert Przybilla

This Letter presents a new, remarkably simple diagnostic specifically designed to derive chemical abundances for high redshift galaxies. It uses only the H \alpha, [N II] and [S II] emission lines, which can usually be observed in a single…

Astrophysics of Galaxies · Physics 2016-02-03 Michael A. Dopita , Lisa J. Kewley , Ralph S. Sutherland , David C. Nicholls

We analyze the stellar abundances of massive galaxies ($\log M_\ast/M_\odot>10.5$) at $z=2$ in the IllustrisTNG simulation with the goal of guiding the interpretation of current and future observations, particularly from the James Webb…

Astrophysics of Galaxies · Physics 2023-05-17 Jee-Ho Kim , Sirio Belli , Rainer Weinberger

To use strong gravitational lenses as an astrophysical or cosmological probe, models of their mass distributions are often needed. We present a new, time-efficient automation code for uniform modeling of strongly lensed quasars with GLEE, a…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-29 S. Ertl , S. Schuldt , S. H. Suyu , T. Schmidt , T. Treu , S. Birrer , A. J. Shajib , D. Sluse

Aims: We developed a new method of estimating the stellar parameters Teff, log g, [M/H], and elemental abundances. This method was implemented in a new code, SP_Ace (Stellar Parameters And Chemical abundances Estimator). This is a highly…

Instrumentation and Methods for Astrophysics · Physics 2016-02-17 C. Boeche , E. K. Grebel

Context. The homogenization of the stellar parameters is an important goal for large observational spectroscopic surveys, but it is very difficult to achieve it because of the diversity of the spectroscopic analysis methods used within a…

We test the performance of our analysis technique for integrated-light spectra by applying it to seven well-studied Galactic GCs that span a wide range of metallicities. Integrated-light spectra were obtained by scanning the slit of the…

Solar and Stellar Astrophysics · Physics 2017-05-10 S. S. Larsen , J. P. Brodie , J. Strader

It is developed a very complex system (hardware/software) to detect luminosity variations connected with the discovery of new planets outside the Solar System. Traditional imaging approaches are very demanding in terms of computing time;…

Computer Vision and Pattern Recognition · Computer Science 2007-05-23 G. Iovane

The program package SME (Spectroscopy Made Easy), designed to perform an analysis of stellar spectra using spectral fitting techniques, was updated due to adding new functions (isotopic and hyperfine splittins) in VALD and including grids…

Instrumentation and Methods for Astrophysics · Physics 2017-10-31 N. Piskunov , T. Ryabchikova , Yu. Pakhomov , T. Sitnova , S. Alexeeva , L. Mashonkina , T. Nordlander

Extragalactic surveys provide significant statistical data for the study of crucial galaxy parameters used to constrain galaxy evolution, e.g. stellar mass (M$_*$) and star formation rate (SFR), under different environmental conditions.…

Astrophysics of Galaxies · Physics 2024-06-12 Paula Calderón-Castillo , Neil M. Nagar , Sukyoung Yi , Yu-Yen Chang , Roger Leiton , Thomas M. Hughes

Measuring distances to galaxies, determining their chemical composition, investigating the nature of their stellar populations and the absorbing properties of their interstellar medium are fundamental activities in modern extragalactic…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Rolf Peter Kudritzki

The faint radio-source population includes sources dominated both by star formation and active galactic nuclei (AGN), encoding the evolution of activity in the Universe. To investigate its nature, we probabilistically classified 4,471 radio…

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