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Magnetic activity in the atmospheres of stars produces a number of spectroscopic signatures that are visible in the shape and strength of spectral lines. These signatures can be used to access, among other things, the variability of the…

Instrumentation and Methods for Astrophysics · Physics 2018-11-29 J. Gomes da Silva , P. Figueira , N. C. Santos , J. P. Faria

We present a spectroscopic survey of galaxies in the COSMOS field using the Fiber Multi-Object Spectrograph (FMOS), a near-infrared instrument on the Subaru Telescope. Our survey is specifically designed to detect the Halpha emission line…

Stellar activity mitigation is one of the major challenges for the detection of earth-like exoplanets in radial velocity (RV) measurements. Several promising techniques are now investigating the use of spectral time-series, to differentiate…

Solar and Stellar Astrophysics · Physics 2023-03-01 Yinan Zhao , Xavier Dumusque

We analyze the X-ray emission and chromospheric activity of Sun-like stars of F, G and K spectral classes (late-type stars) studied in the framework of the HK project. More powerful coronas are possessed by stars displaying irregular…

Solar and Stellar Astrophysics · Physics 2018-07-19 E. A. Bruevich , M. M. Katsova , D. D. Sokolov

Many low-frequency radio interferometers are aiming to detect very faint spectral signatures from structures at cosmological redshifts, particularly of neutral Hydrogen using its characteristic 21 cm spectral line. Due to the very high…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-03 Nithyanandan Thyagarajan , Chris Carilli

This is the first in a series of three papers describing a project with the Cosmic Origins Spectrograph on the Hubble Space Telescope to measure abundances of the neutral interstellar medium (ISM) in a sample of 9 nearby star-forming…

Astrophysics of Galaxies · Physics 2015-06-22 Bethan L. James , Alessandra Aloisi , Timothy M. Heckman , Sangmo Tony Sohn , Michael A. Wolfe

Intensive reverberation mapping monitoring programs combine ground-based photometric observations from different telescopes, requiring intercalibration of lightcurves to reduce systematic instrumental differences. We present a new iterative…

Instrumentation and Methods for Astrophysics · Physics 2025-06-02 Roberta Vieliute , Juan V. Hernández Santisteban , Keith Horne , Hannah Cornfield

Current cosmological analyses which use Type Ia supernova (SN Ia) observations combine SN samples to expand the redshift range beyond that of a single sample and increase the overall sample size. The inhomogeneous photometric calibration…

The Pristine survey is a narrow-band, photometric survey focused around the wavelength region of the Ca II H & K absorption lines, designed to efficiently search for extremely metal-poor stars. In this work, we use the first results of a…

Asteroseismology is a powerful way of determining stellar parameters and properties of stars like the Sun. However, main-sequence F-type stars exhibit short mode lifetimes relative to their oscillation frequency, resulting in overlapping…

Solar and Stellar Astrophysics · Physics 2019-02-18 Douglas L. Compton , Timothy R. Bedding , Dennis Stello

Inversion codes allow reconstructing a model atmosphere from observations. With the inclusion of optically thick lines that form in the solar chromosphere, such modelling is computationally very expensive because a non-LTE evaluation of the…

Solar and Stellar Astrophysics · Physics 2019-04-19 Alberto Sainz Dalda , Jaime de la Cruz Rodríguez , Bart De Pontieu , Milan Gošić

This work presents an approach (fitCMD) designed to obtain a comprehensive set of astrophysical parameters from colour-magnitude diagrams (CMDs) of star clusters. Based on initial mass function (IMF) properties taken from isochrones, fitCMD…

Instrumentation and Methods for Astrophysics · Physics 2018-12-12 Charles Bonatto

We present a Bayesian Stacking technique to directly measure the HI mass function (HIMF) and its evolution with redshift using galaxies formally below the nominal detection threshold. We generate galaxy samples over several sky areas given…

Astrophysics of Galaxies · Physics 2020-01-08 Hengxing Pan , Matt J. Jarvis , James R. Allison , Ian Heywood , Mario G. Santos , Natasha Maddox , Bradley S. Frank , Xi Kang

One of the main goals of the COROT mission is to get precise photometric observations of selected bright stars in order to allow the modelling of their interior through asteroseismology. However, in order to interpret the…

Astrophysics · Physics 2009-11-11 M. Gillon , P. Magain

Cool giant and supergiant star atmospheres are characterized by complex velocity fields originating from convection and pulsation processes which are not fully understood yet. The velocity fields impact the formation of spectral lines,…

Solar and Stellar Astrophysics · Physics 2018-02-21 K. Kravchenko , S. Van Eck , A. Chiavassa , A. Jorissen , B. Freytag , B. Plez

Studying the anharmonicity in the infrared (IR) spectra of polycyclic aromatic hydrocarbons (PAHs) at elevated temperatures is important to understand vibrational features and chemical properties of interstellar dust, especially in the…

We present a method, based on Bayesian statistics, to fit the dust emission parameters in the far-infrared and submillimeter wavelengths. The method estimates the dust temperature and spectral emissivity index, plus their relationship,…

Astrophysics of Galaxies · Physics 2015-06-15 M. Veneziani , F. Piacentini , A. Noriega-Crespo , S. Carey , R. Paladini , D. Paradis

The measurement of type Ia supernovae magnitudes provides cosmological distances, which can be used to constrain dark energy parameters. Large photometric surveys require a substantial improvement in the calibration precision of their…

The [O II] lambda3727 emission lines and absorption features from stellar Balmer and Ca H&K lines are the most accessible kinematic diagnotics in galaxies at z~1. We investigate the kinematics of 22 local late-type galaxies using these…

Astrophysics · Physics 2007-05-23 Chip Kobulnicky , Karl Gebhardt

Spectral inversion codes are powerful tools to analyze spectropolarimetric observations, and they provide important diagnostics of solar magnetic fields. Inversion codes differ by numerical procedures, approximations of the atmospheric…

Solar and Stellar Astrophysics · Physics 2015-06-04 H. Balthasar , M. L. Demidov