Search Publications
A time-dependent photochemical model for Titan's atmosphere and the origin of H2O
Lara, L. M.; Lellouch, E.; Moreno, R. +2 more
Context. Titan's stratosphere contains oxygen compounds (CO, CO2, and H2O), implying an external source of oxygen whose nature is still uncertain. Recent observations from the Herschel Space Observatory using the HIFI and PACS instruments and the Cassini/CIRS, as well as steady-state photochemical modeling indicate that the a…
The coronal energy input from magnetic braiding
Yeates, A. R.; Welsch, B. T.; Bianchi, F. +1 more
We estimate the energy input into the solar corona from photospheric footpoint motions, using observations of a plage region by the Hinode Solar Optical Telescope. Assuming a perfectly ideal coronal evolution, two alternative lower bounds for the Poynting flux are computed based on field line footpoint trajectories, without requiring horizontal ma…
Differential emission measure analysis of active region cores and quiet Sun for the non-Maxwellian κ-distributions
Dzifčáková, E.; Dudík, J.; Mackovjak, Š.
Context. The non-Maxwellian κ-distributions have been detected in the solar wind and can explain intensities of some transition region lines. Presence of such distributions in the outer layers of the solar atmosphere influences the ionization and excitation equilibrium and widens the line contribution functions. This behavior may be reflected on t…
Atmospheric parameters and carbon abundance for hot DB white dwarfs
Gänsicke, B. T.; Koester, D.; Provencal, J.
Atmospheric parameters for hot DB (helium atmosphere) white dwarfs near effective temperatures of 25 000 K are extremely difficult to determine from optical spectroscopy. The neutral He lines reach a maximum in this range and change very little with effective temperature and surface gravity. Moreover, an often unknown amount of hydrogen contaminat…
A quiescent galaxy at the position of the long GRB 050219A
Covino, S.; Pian, E.; D'Elia, V. +25 more
Context. Long-duration gamma-ray bursts (LGRBs) are produced by the collapse of very massive stars. Because of the short life time of their progenitors, LGRBs pinpoint star-forming galaxies. Recent studies demonstrate that LGRBs populate all types of star-forming galaxies from sub-luminous, blue compact dwarfs to luminous infrared galaxies.
A…
Wind collisions in three massive stars of Cygnus OB2
Nazé, Yaël; Rauw, Gregor; Cazorla, Constantin
Aims: We wish to study the origin of the X-ray emission of three massive stars in the Cyg OB2 association: Cyg OB2 #5, Cyg OB2 #8A, and Cyg OB2 #12.
Methods: To this aim, dedicated X-ray observations from XMM-Newton and Swift are used, as well as archival ROSAT and Suzaku data.
Results: Our results on Cyg OB2 #8A improve the phase c…
A non-equilibrium ortho-to-para ratio of water in the Orion PDR
Bergin, E. A.; Plume, R.; van der Tak, F. F. S. +1 more
Context. The ortho-to-para ratio (OPR) of H2O is thought to be sensitive to the temperature of water formation. The OPR of H2O is thus useful for studying the formation mechanism of water.
Aims: We investigate the OPR of water in the Orion PDR (photon-dominated region), at the Orion Bar and Orion S positions, using data …
Deep optical observations of the γ-ray pulsar J0357+3205
Zharikov, S.; Shternin, P.; Kirichenko, A. +3 more
Context. A middle-aged radio-quiet pulsar J0357+3205 was discovered in gamma rays with Fermi and later in X-rays with Chandra and XMM-Newton observatories. It produces an unusual thermally emitting pulsar wind nebula that is observed in X-rays.
Aims: Deep optical observations were obtained to search for the pulsar optical counterpart and its …
Planetary companions in K giants β Cancri, µ Leonis, and β Ursae Minoris
Hatzes, A. P.; Lee, B. -C.; Park, M. -G. +3 more
Aims: The aim of our paper is to investigate the low-amplitude and long-period variations in evolved stars with a precise radial velocity survey.
Methods: The high-resolution, the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used from 2003 to 2013 for a radial velocity survey of giant stars as part of the exoplanet sea…
The scale height of gas traced by [C ii] in the Galactic plane
Langer, W. D.; Pineda, J. L.; Velusamy, T.
Context. The distribution of various interstellar gas components and the pressure in the interstellar medium (ISM) is a result of the interplay of different dynamical mechanisms and energy sources on the gas in the Milky Way. The scale heights of the different gas tracers, such as H i and CO, are a measure of these processes. The scale height of […