Search Publications
Techniques and Review of Absolute Flux Calibration from the Ultraviolet to the Mid-Infrared
Gordon, Karl D.; Tremblay, P. -E.; Bohlin, Ralph C.
The measurement of precise absolute fluxes for stellar sources has been pursued with increased vigor since the discovery of the dark energy and the realization that its detailed understanding requires accurate spectral energy distributions (SEDs) of redshifted Ia supernovae in the rest frame. The flux distributions of spectrophotometric standard s…
The Typecasting of Active Galactic Nuclei: Mrk 590 no Longer Fits the Role
Martini, P.; Peterson, B. M.; Pogge, R. W. +9 more
We present multiwavelength observations that trace more than 40 yr in the life of the active galactic nucleus (AGN) in Mrk 590, traditionally known as a classic Seyfert 1 galaxy. From spectra recently obtained from Hubble Space Telescope, Chandra, and the Large Binocular Telescope, we find that the activity in the nucleus of Mrk 590 has diminished…
The Wolf-Rayet stars in the Large Magellanic Cloud. A comprehensive analysis of the WN class
Foellmi, C.; Hamann, W. -R.; Oskinova, L. M. +6 more
Context. Massive stars, although being important building blocks of galaxies, are still not fully understood. This especially holds true for Wolf-Rayet (WR) stars with their strong mass loss, whose spectral analysis requires adequate model atmospheres.
Aims: Following our comprehensive studies of the WR stars in the Milky Way, we now present …
The VLT-FLAMES Tarantula Survey. XVII. Physical and wind properties of massive stars at the top of the main sequence
Crowther, P. A.; Herrero, A.; Simón-Díaz, S. +12 more
The evolution and fate of very massive stars (VMS) is tightly connected to their mass-loss properties. Their initial and final masses differ significantly as a result of mass loss. VMS have strong stellar winds and extremely high ionising fluxes, which are thought to be critical sources of both mechanical and radiative feedback in giant H ii regio…
Dust in the diffuse interstellar medium. Extinction, emission, linear and circular polarisation
Siebenmorgen, R.; Bagnulo, S.; Voshchinnikov, N. V.
We present a model for the diffuse interstellar dust that explains the observed wavelength-dependence of extinction, emission, and the linear and circular polarisation of light. The model is set up with a small number of parameters. It consists of a mixture of amorphous carbon and silicate grains with sizes from the molecular domain of 0.5 up to a…
Reverberation Mapping of the Seyfert 1 Galaxy NGC 7469
Motohara, K.; Skowron, D. M.; Skowron, J. +43 more
A large reverberation-mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hβ λ4861 and He II λ4686 and a central black hole mass measurement M BH ≈ 1 × 107 M ⊙, consistent with previous measurements. A very low level of variability during the monitoring campaign precluded meeting our o…
Hubble Space Telescope CALSPEC Flux Standards: Sirius (and Vega)
Bohlin, R. C.
The Space Telescope Imaging Spectrograph (STIS) has measured the flux for Sirius from 0.17 to 1.01 µm on the Hubble Space Telescope (HST) White Dwarf scale. Because of the cool debris disk around Vega, Sirius is commonly recommended as the primary IR flux standard. The measured STIS flux agrees well with predictions of a special Kurucz model…
Physical properties of fullerene-containing Galactic planetary nebulae
Otsuka, Masaaki; Peeters, E.; Bernard-Salas, J. +2 more
We searched the Spitzer Space Telescope data archive for Galactic planetary nebulae (PNe), which show the characteristic 17.4 and 18.9 µm features due to C60, also known as buckminsterfullerene. Out of 338 objects with Spitzer/Infrared Spectrograph data, we found eleven C60-containing PNe, six of which (Hen2-68, IC2501,…
Winds of Low-metallicity OB-type Stars: HST-COS Spectroscopy in IC 1613
Garcia, Miriam; Herrero, Artemio; Najarro, Francisco +2 more
We present the first quantitative ultraviolet spectroscopic analysis of resolved OB stars in IC 1613. Because of its alleged very low metallicity (lsim1/10 Z ⊙, from H II regions), studies in this Local Group dwarf galaxy could become a significant step forward from the Small Magellanic Cloud (SMC) toward the extremely metal-poor massiv…
Influence of physical galaxy properties on Lyα escape in star-forming galaxies
Hayes, Matthew; Schaerer, Daniel; Östlin, Göran +4 more
Context. Among the different observational techniques used to select high-redshift galaxies, the hydrogen recombination line Lyman-alpha (Lyα) is of particular interest because it gives access to the measurement of cosmological quantities such as the star formation rate (SFR) of distant galaxy populations. However, interpreting this line and calib…