Search Publications
Empirical estimate of Lyα escape fraction in a statistical sample of Lyα emitters
Schaerer, D.; Östlin, G.; Hayes, M. +4 more
Context: The Lyman-alpha (Lyα) recombination line is a fundamental tool for galaxy evolution studies and modern observational cosmology. However, subsequent interpretations are still prone to a number of uncertainties. Besides numerical efforts, empirical data are urgently needed for a better understanding of the Lyα escape process.
Aims: We e…
A cool starspot or a second transiting planet in the TrES-1 system?
Alonso, R.; Deeg, H. J.; Brown, T. M. +6 more
Aims: We investigate the origin of a flux increase found during a transit of TrES-1, observed with the HST (Hubble Space Telescope). This feature in the HST light curve cannot be attributed to noise and is supposedly a dark area on the stellar surface of the host star eclipsed by TrES-1 during its transit. We investigate the likelihood of two poss…
The size-density relation of extragalactic H II regions
Hunt, L. K.; Hirashita, H.
Aims: We investigate the size-density relation in extragalactic H ii regions, with the aim of understanding the role of dust and different physical conditions in the ionized medium.
Methods: First, we compiled several observational data sets for Galactic and extragalactic H ii regions and confirm that extragalactic H ii regions follow the same…
Quiet Sun mini-coronal mass ejections activated by supergranular flows
Innes, D. E.; Potts, H. E.; Attie, R. +1 more
Context: The atmosphere of the quiet Sun is controlled by photospheric flows sweeping up concentrations of mixed polarity magnetic field. Along supergranule boundaries and junctions, there is a strong correlation between magnetic flux and bright chromospheric and transition region emission.
Aims: The aim is to investigate the relationship betw…
A joint spectro-imaging analysis of the XMM-Newton and HESS observations of the supernova remnant RX J1713.7-3946
Ballet, J.; Lemoine-Goumard, M.; Decourchelle, A. +5 more
Context: The supernova remnant (SNR) RX J1713.7-3946 (also known as G347.3-0.5) is part of the class of remnants dominated by synchrotron emission in X-rays. It is also one of the few shell-type SNRs observed at TeV energies allowing us to investigate particle acceleration at SNRs shock.
Aims: Our goal is to compare spatial and spectral proper…
XMM-Newton observations of Seyfert galaxies from the Palomar spectroscopic survey: the X-ray absorption distribution
Georgantopoulos, I.; Akylas, A.
We present XMM-Newton spectral analysis of all 38 Seyfert galaxies from the Palomar spectroscopic sample of galaxies. These are found at distances of up to 67 Mpc and cover the absorbed 2-10 keV luminosity range ~1038-1043 erg s-1. Our aim is to determine the distribution of the X-ray absorption in the local Univer…
Lithium abundances of halo dwarfs based on excitation temperature. I. Local thermodynamic equilibrium
García Pérez, A. E.; Norris, J. E.; Ryan, S. G. +2 more
Context: The discovery of the Spite plateau in the abundances of 7Li for metal-poor stars led to the determination of an observationally deduced primordial lithium abundance. However, after the success of the Wilkinson Microwave Anisotropy Probe (WMAP) in determining the baryon density, Ω_Bh2, there was a discrepancy between …
Designing future dark energy space missions. I. Building realistic galaxy spectro-photometric catalogs and their first applications
Kneib, J. -P.; Aussel, H.; Ilbert, O. +12 more
Context: Future dark energy space missions such as JDEM and EUCLID are being designed to survey the galaxy population to trace the geometry of the universe and the growth of structure, which both depend on the cosmological model. To reach the goal of high precision cosmology they need to evaluate the capabilities of different instrument designs ba…
The physical properties of Lyα emitting galaxies: not just primeval galaxies?
Castellano, M.; Pentericci, L.; Santini, P. +4 more
Aims: We have analyzed a sample of Lyman break galaxies from z ~ 3.5 to z ~ 6 selected from the GOODS-S field as B, V, and i-dropouts, and with spectroscopic observations showing that they have the Lyα line in emission. Our main aim is to investigate their physical properties and their dependence on the emission line characteristic and to shed lig…
The radial distribution of the two stellar populations in NGC 1851
Salaris, M.; Anderson, J.; Milone, A. P. +4 more
We have analyzed ACS/WFC and WFPC2 images from HST, as well as ground-based data to study the radial distribution of the double sub-giant branch (SGB) recently discovered in the Galactic globular cluster NGC 1851. We found that the SGB split can be followed all the way from the cluster center out to at least 8´ from the center. Beyond this distanc…