相关论文: Indicators of star formation: 4000 Angstrom break …
The optical regime is historically the best-studied wavelenght range. Gas ionized by massive stars produces optical emission lines that have been used to derive indicators of star-formation rate, metallicity, dust reddening, and the…
A spectrophotometric model able to compute the integrated spectrum of a galaxy, including the contribution both of the stellar populations and of the ionized interstellar gas of the HII regions powered by young hot stars, has been used to…
Aim: The aim is to study the stellar content of the bar region to constrain its formation and evolution. Methods: Line-strength indices in the bar region of a sample of 6 barred galaxies were employed to derive age and metallicity gradients…
Binary stars have been shown to have a substantial impact on the integrated light of stellar populations, particularly at low metallicity and early ages - conditions prevalent in the distant Universe. But the fraction of stars in stellar…
Since Be stars belong to the high velocity tail of a single B star velocity distribution, the appearance of the Be phenomenon must be independent of the stellar mass. In the present paper we show that the shape of the distribution of the…
Aims. We present a spectroscopic study of the properties of 64 Balmer break galaxies that show signs of star formation. The studied sample of star-forming galaxies spans a redshift range from 0.094 to 1.475 with stellar masses in the range…
Kjeldsen et al. (1995, AJ 109, 1313; astro-ph/9411016) have developed a new technique for measuring stellar oscillations and claimed a detection in the G subgiant eta Boo. The technique involves monitoring temperature fluctuations in a star…
(shortened) We have obtained blue integrated spectra of 175 nearby early-type galaxies, covering a wide range in galaxy velocity dispersion, and emphasizing those with sigma < 100 km/s. Galaxies have been observed both in the Virgo cluster…
An analysis of H alpha and H beta spectra in a sample of 30 cool dwarf and subgiant stars is presented using MARCS model atmospheres based on the most recent calculations of the line opacities. A detailed quantitative comparison of the…
Balmer lines serve as important indicators of stellar effective temperatures in late-type stellar spectra. One of their modelling uncertainties is the influence of convective flows on their shape. We aim to characterize the influence of…
The intensities of the hydrogen Balmer lines of solar-like stars are investigated for stellar chromospheric activity by using the co-source spectral data of the LAMOST Low-Resolution Spectroscopic Survey (LRS) and Medium-Resolution…
To analyse stellar populations in galaxies a widely used method is to apply theoretically derived responses of stellar spectra and line indices to element abundance variations, hereafter referred to as response functions. These are applied…
Stellar population models to predict the H Balmer and HeI lines in absorption are presented. Models are computed for burst and continuous star formation. It is found that the Balmer and HeI line profiles are sensitive to the age, except…
With the successful launch and commissioning of JWST we are now able to routinely spectroscopically probe the rest-frame optical emission of galaxies at $z>6$ for the first time. Amongst the most useful spectral diagnostics used in the…
Magnetic fields and stellar spots can alter the equivalent widths of absorption lines in stellar spectra, varying during the activity cycle. This also influences the information that we derive through spectroscopic analysis. In this study…
Through the study of two absorption spectral features in the optical range (Mg2 and the 4000 A break), we find evidence for star formation in the inner regions of cooling-flow galaxies. The application of simple stellar population models…
We use near-infrared (NIR) spectroscopy obtained with GNIRS on Gemini, NIRSPEC on KECK, and ISAAC on the VLT to study the rest-frame optical continua of three `Distant Red Galaxies' (having Js - Ks > 2.3) at z>2. All three galaxy spectra…
From stellar spectra, a variety of physical properties of stars can be derived. In particular, the chemical composition of stellar atmospheres can be inferred from absorption line analyses. These provide key information on large scales,…
Standard models of structure formation allow us to predict the cosmic timescales relevant for the onset of star formation and the assembly history of galaxies at high redshifts ($z > 10$). The strength of the Balmer break represents a…
Balmer lines are an important diagnostic of stellar atmospheric structure, since they are formed at a wide range of depths within the atmosphere. The different Balmer lines are formed at slightly different depths making them useful…