Search Publications
New bright optical spectrophotometric standards: A-type stars from the STIS Next Generation Spectral Library
del Burgo, C.; Allende Prieto, C.
Exoplanets have sparked interest in extremely high signal-to-noise ratio spectroscopic observations of very bright stars, in a regime where flux calibrators, in particular DA white dwarfs, are not available. We argue that A-type stars offer a useful alternative and reliable space-based spectrophotometry is now available for a number of bright ones…
The Agilkia boulders/pebbles size-frequency distributions: OSIRIS and ROLIS joint observations of 67P surface
Jorda, L.; Lamy, P. L.; Jaumann, R. +57 more
By using the images acquired by the OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System) and ROLIS (ROsetta Lander Imaging System) cameras, we derive the size-frequency distribution (SFD) of cometary pebbles and boulders covering the size range 0.05-30.0 m on the Agilkia landing site. The global SFD measured on OSIRIS images, reflect…
MUSE three-dimensional spectroscopy and kinematics of the gigahertz peaked spectrum radio galaxy PKS 1934-63: interaction, recently triggered active galactic nucleus and star formation
Roche, Nathan; Humphrey, Andrew; Lagos, Patricio +4 more
We observe the radio galaxy PKS 1934-63 (at z = 0.1825) using the Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT). The radio source is a gigahertz peaked spectrum source and is compact (0.13 kpc), implying an early stage of evolution (≤104 yr). Our data show an interacting pair of galaxies, with projected sepa…
The tight subgiant branch of the intermediate-age star cluster NGC 411 implies a single-aged stellar population
Bastian, N.; Niederhofer, F.; Li, C. +3 more
The presence of extended main-sequence turn-off (eMSTO) regions in intermediate-age star clusters in the Large and Small Magellanic Clouds is often interpreted as resulting from extended star formation histories (SFHs), lasting ≥300 Myr. This strongly conflicts with the traditional view of the dominant star formation mode in stellar clusters, whic…
No signatures of black hole spin in the X-ray spectrum of the Seyfert 1 galaxy Fairall 9
Turner, T. J.; Yaqoob, T.; Tatum, M. M. +2 more
Fairall 9 is one of several type 1 active galactic nuclei for which it has been claimed that the angular momentum (or spin) of the supermassive black hole can be robustly measured, using the Fe Kα emission line and Compton-reflection continuum in the X-ray spectrum. The method rests upon the interpretation of the Fe Kα line profile and associated …
Investigation of the energy dependence of the orbital light curve in LS 5039
Zhang, S.; Kretschmar, P.; Kuulkers, E. +5 more
LS 5039 is so far the best-studied γ-ray binary system at multiwavelength energies. A time-resolved study of its spectral energy distribution (SED) shows that above 1 keV its power output is changing along its binary orbit as well as being a function of energy. To disentangle the energy dependence of the power output as a function of orbital phase…
ALMA probes the molecular gas reservoirs in the changing-look Seyfert galaxy Mrk 590
Vestergaard, M.; Peterson, B. M.; Koay, J. Y. +2 more
We investigate if the active galactic nucleus (AGN) of Mrk 590, whose supermassive black hole was until recently highly accreting, is turning off due to a lack of central gas to fuel it. We analyse new subarcsecond resolution Atacama Large Millimetre/submilllimetre Array maps of the 12CO(3-2) line and 344 GHz continuum emission in Mrk 5…
Gamma-ray burst polarization reduction induced by the Lorentz invariance violation
Chang, Zhe; Li, Xin; Lin, Hai-Nan
It has been observed that photons in the prompt emission of some gamma-ray bursts (GRBs) are highly polarized. The high polarization is used by some authors to give a strict constraint on the Lorentz invariance violation (LIV). If the Lorentz invariance is broken, the polarization vector of a photon may rotate during its propagation. The rotation …
Limb-darkening coefficients from line-blanketed non-LTE hot-star model atmospheres
Howarth, I. D.; Reeve, D. C.
We present grids of limb-darkening coefficients computed from non-local thermodynamic equilibrium (non-LTE), line-blanketed TLUSTY model atmospheres, covering effective-temperature and surface-gravity ranges of 15-55 kK and 4.75 dex (cgs) down to the effective Eddington limit, at 2×, 1×, 0.5× (Large Magellanic Cloud), 0.2× (Small Magellanic Cloud)…
Searching for FUV line emission from 107 K gas in massive elliptical galaxies and galaxy clusters as a tracer of turbulent velocities
Anderson, Michael E.; Sunyaev, Rashid
Non-thermal pressure from turbulence and bulk flows is a fundamental ingredient in hot gaseous haloes, and in the intracluster medium, it will be measured through emission line kinematics with calorimeters on future X-ray spacecraft. In this paper, we present a complementary method for measuring these effects, using forbidden FUV emission lines of…