Search Publications
Herschel and IRAM-30 m observations of comet C/2012 S1 (ISON) at 4.5 AU from the Sun
Altieri, B.; Jorda, L.; Küppers, M. +9 more
Context. The sungrazer comet C/2012 S1 (ISON) (perihelion at rh = 0.0125 AU from the Sun) was bright and active when discovered in September 2012 at 6.3 AU from the Sun.
Aims: Our goal was to characterize the distant gaseous and dust activity of this comet, inbound, from observations of H2O, CO and the dust coma in the f…
Population gradients and photometric metallicities in early- and transition-type dwarf galaxies: Clues from the Sculptor group
Rejkuba, M.; Da Costa, G. S.; Grebel, E. K. +3 more
Aims: We focus on the resolved stellar populations of one early-type and four transition-type dwarf galaxies in the Sculptor group, with the aim to examine the potential presence of population gradients and place constraints on their mean metallicities.
Methods: We use deep Hubble Space Telescope images to construct color-magnitude diagr…
Evidence for partial Taylor relaxation from changes in magnetic geometry and energy during a solar flare
Bloomfield, D. S.; Gallagher, P. T.; Murray, S. A.
Context. Solar flares are powered by energy stored in the coronal magnetic field, a portion of which is released when the field reconfigures into a lower energy state. Investigation of sunspot magnetic field topology during flare activity is useful to improve our understanding of flaring processes.
Aims: Here we investigate the deviation of t…
Detection of X-rays from the jet-driving symbiotic star Hen 3-1341
Sokoloski, J. L.; Luna, G. J. M.; Stute, M. +1 more
Context. Hen 3-1341 is a symbiotic binary system consisting of a white dwarf and a red giant star that is one of about ten symbiotics that show hints of jets. The bipolar jets have been detected through displaced components of emission lines during its outburst from 1998 to 2004. These components disappeared when Hen 3-1341 reached quiescence. On …
VLA/JVLA monitoring of bright northern radio sources
López-Caniego, M.; Partridge, B.; Myers, S. +3 more
We report multiple epoch VLA/JVLA observations of 89 northern hemisphere sources, most with 37 GHz flux density >1 Jy, observed at 4.8, 8.5, 33.5, and 43.3 GHz. The high frequency selection leads to a predominantly flat spectrum sample, with 85% of our sources being in the Planck Early Release Compact Source Catalog (ERCSC). These observations …
Submillimeter observations of IRAS and WISE debris disk candidates
Dowell, C. D.; De Rosa, R. J.; McCarthy, D. +7 more
A set of six debris disk candidates identified with IRAS or WISE excesses were observed at either 350 µm or 450 µm with the Caltech Submillimeter Observatory. Five of the targets - HIP 51658, HIP 68160, HIP 73512, HIP 76375, and HIP 112460 - have among the largest measured excess emission from cold dust from IRAS in the 25-100 µm…
Fluctuations of the intergalactic ionization field at redshift z ~ 2
Reimers, D.; Hagen, H. -J.; Levshakov, S. A. +2 more
Aims: To probe the spectral energy distribution (SED) of the ionizing background radiation at z ≲ 2 and to specify the sources contributing to the intergalactic radiation field.
Methods: The spectrum of a bright quasar
WR 138: new results from X-ray and optical spectroscopy
Nazé, Y.; Rauw, G.; De Becker, M. +2 more
Context. Massive-binary evolution models predict that some systems will go through an evolutionary phase where the original primary has become a supernova and left a compact object behind that then orbits a Wolf-Rayet (WR) star. WR 138 is an X-ray bright WR star that has been described as a triple system, including a compact companion in a short-p…
The multiplicity of φ Phe revisited
Pourbaix, D.; Chini, R.; Boffin, H. M. J. +1 more
Aims: The chemically peculiar B star φ Phe was, until very recently, considered to be a triple system, even though the data were not conclusive and the orbits rather uncertain. Very recent results provided a revised orbit, different from the then available astrometric Hipparcos orbit.
Methods: Additional spectroscopic data obtained with …
Empirical determination of the temperature stratification in the photosphere of the quiet Sun
Faurobert, M.; Ricort, G.; Aime, C.
Context. Detailed realistic 3D simulations of the photosphere of the Sun are now available, but 1D models of the average quiet-Sun photosphere are still widely used, in particular for spectro-polarimetric inversions.
Aims: Here we present an empirical determination of the average radiation temperature variations as a function of the geometric…