Search Publications
Similarities of magnetoconvection in the umbra and in the penumbra of sunspots
Solanki, S. K.; Lagg, A.; Löptien, B. +1 more
Context. It is unclear why there is a rather sharp boundary in sunspots between the umbra and the penumbra. Both regions exhibit magnetoconvection, which manifests in penumbral filaments in the penumbra and in umbral dots in the umbra.
Aims: Here we compare the physical properties of umbral dots and penumbral filaments. Our goal is to underst…
Ancient and present surface evolution processes in the Ash region of comet 67P/Churyumov-Gerasimenko
Jorda, L.; Groussin, O.; Bouley, S. +3 more
Aims: The Rosetta mission provided us with detailed data of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko. In order to better understand the physical processes associated with the comet activity and the surface evolution of its nucleus, we performed a detailed comparative morphometrical analysis of two depressions located in t…
X-ray emission of Seyfert 2 galaxy MCG-01-24-12
Bianchi, S.; Dadina, M.; Braito, V. +7 more
We present a detailed X-ray spectral analysis of the nearby Seyfert 2 galaxy MCG-01-24-12 based on a multi-epoch data set. Data were obtained with different X-ray satellites, namely XMM-Newton, NuSTAR, Swift, and Chandra, and cover different time intervals, from a few days to years. From 2006 to 2013 the source had a 2-10 keV flux of ∼1.5 × 10
Stellar X-rays and magnetic activity in 3D MHD coronal models
Peter, H.; Zhuleku, J.; Warnecke, J.
Context. Observations suggest a power-law relation between the coronal emission in X-rays, LX, and the total (unsigned) magnetic flux at the stellar surface, Φ. The physics basis for this relation is poorly understood.
Aims: We use three-dimensional (3D) magnetohydrodynamics (MHD) numerical models of the coronae above active region…
New precise positions in 2013-2019 and a catalog of ground-based astrometric observations of 11 Neptunian satellites (1847-2019) based on Gaia-DR2
Ren, Shulin; Fu, Yanning; Yuan, Ye +1 more
Context. Developing high-precision ephemerides for Neptunian satellites requires not only the continuation of observing campaigns but also the collection and improvement of existing observations. So far, no complete catalogs of observations of Neptunian satellites are available.
Aims: We aim to provide new, precise positions, and to compile a…
Over-expansion of a coronal mass ejection generates sub-Alfvénic plasma conditions in the solar wind at Earth
Schmieder, B.; Poedts, S.; Démoulin, P. +4 more
Context. From May 24-25, 2002, four spacecraft located in the solar wind at about 1 astronomical unit (au) measured plasma densities one to two orders of magnitude lower than usual. The density was so low that the flow became sub-Alfvénic for four hours, and the Alfvén Mach number was as low as 0.4. Consequently, the Earth lost its bow shock, and …
Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. VII. Elder suns with low-mass companions
Adamów, M.; Maciejewski, G.; Villaver, E. +3 more
Context. We present the current status of and new results from our search for exoplanets in a sample of solar-mass evolved stars observed with the HARPS-N and the 3.6 m Telescopio Nazionale Galileo (TNG), and the High-Resolution Spectrograph (HRS) and the 9.2 m Hobby-Eberly Telescope (HET).
Aims: The aim of this project is to detect and chara…
The GRAVITY young stellar object survey. V. The orbit of the T Tauri binary star WW Cha
Genzel, R.; Sturm, E.; Duchêne, G. +60 more
Context. Close young binary stars are unique laboratories for the direct measurement of pre-main-sequence (PMS) stellar masses and their comparison to evolutionary theoretical models. At the same time, a precise knowledge of their orbital parameters when still in the PMS phase offers an excellent opportunity for understanding the influence of dyna…
A new search for star forming regions in the southern outer Galaxy
König, C.; Menten, K. M.; Wyrowski, F. +2 more
Context. Star formation in the outer Galaxy is thought to be different from that in the inner Galaxy, as it is subject to different environmental parameters such as metallicity, interstellar radiation field, or mass surface density, which all change with galactocentric radius. Extending our star formation knowledge, from the inner to the outer Gal…
Detecting the intrinsic X-ray emission from the O-type donor star and the residual accretion in a supergiant fast X-ray transient in its faintest state
Salvaterra, R.; Marelli, M.; Sidoli, L. +4 more
We report on the results of an XMM-Newton observation of the supergiant fast X-ray transient (SFXT) IGR J08408-4503 performed in June 2020. The source is composed of a compact object (likely a neutron star) orbiting around an O8.5Ib-II(f)p star, LM Vel. The X-ray light curve shows a very low level of emission, punctuated by a single, faint flare. …