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Plasma Transport in Saturn's Low-Latitude Ionosphere: Cassini Data
Wahlund, J. -E.; Waite, J. H.; Cravens, T. E. +7 more
In 2017 the Cassini Orbiter made the first in situ measurements of the upper atmosphere and ionosphere of Saturn. The Ion and Neutral Mass Spectrometer in its ion mode measured densities of light ion species (H+, H2+, H3+, and He+), and the Radio and Plasma Wave Science instrument m…
Chemical Composition of Globular Clusters of Milky Way Subsystems from Gaia DR2 Data
Bobylev, V. V.; Bajkova, A. T.; Korchagin, V. I. +1 more
Results of a study of the kinematic and chemical properties of globular clusters of the Milky Way based on data from the Gaia DR2 catalog and meaurements with the Hubble Space Telescope are presented. A new method for dividing globular clusters into Galatic subsystems based on the elements of their Galactic orbits is proposed. Samples of globular …
A study of full space motions of outer Galactic disc A and F stars in two deep pencil beams
Monguió, M.; Harris, A.; Drew, J. E.
A and F stars can be used as probes of outer Galactic disc kinematics: here we extend the work of Harris et al. by cross-matching their A/F sample with Gaia DR2 to bring in proper motions. These are combined with the already measured radial velocities and spectrophotometric distances to obtain full space motions. We use this sample of 1173 stars, …
A revisit to the enigmatic variable star 21 Comae
Kallinger, Thomas; Pribulla, Theodor; Walczak, Przemysław +12 more
The magnetic chemically peculiar (Ap/CP2) star 21 Com has been extensively studied in the past, albeit with widely differing and sometimes contradictory results, in particular concerning the occurrence of short-term variability between about 5 to 90 min. We have performed a new investigation of 21 Com using Microvariability and Oscillations of Sta…
Concerning the occurrence of bow shocks around high-mass X-ray binaries
Prišegen, M.
Context. We investigate the occurrence of stellar bow shocks around high-mass X-ray binaries (HMXBs) in the Galaxy.
Aims: We seek to conduct a survey of HMXBs in the mid-infrared to search for the presence of bow shocks around these objects.
Methods: Telescopes operating in the mid-infrared, such as the Spitzer Space Telescope or Wide-fi…
Infrared and sub-mm observations of outbursting young stars with Herschel and Spitzer
Rab, C.; Audard, M.; Güdel, M. +3 more
Context. Episodic accretion plays an important role in the evolution of young stars. Although it has been under investigation for a long time, the origin of such episodic accretion events is not yet understood.
Aims: We investigate the dust and gas emission of a sample of young outbursting sources in the infrared to get a better understanding…
Envelopes and vertical amplitudes of disc-crossing orbits
Vieira, Ronaldo S. S.; Ramos-Caro, Javier
We recently found that regular orbits in axially symmetric galactic discs have their envelopes Z(R) accurately described by the relation Z(R)∝[ΣI(R)]-1/3, if their amplitudes are comparable to the disc thickness, where ΣI is the surface density of the disc (integrated over its whole vertical range). Moreover, the u…
Magnetic fields and extraordinarily bright radio emission in the X-ray faint galaxy group MRC 0116 + 111
Böhringer, H.; Simionescu, A.; Mernier, F. +4 more
MRC 0116 + 111 is a nearby (z = 0.132) poor galaxy group, which was previously known for exhibiting a bright diffuse radio emission with no central point-like source, presumably related to a past activity of the active galactic nucleus (AGN) in its central cD galaxy. Here, we present an X-ray observation (∼30 ks of cleaned XMM-Newton/EPIC exposure…
Enhanced Ionization in Magnetic Anomaly Regions of the Martian Lower Ionosphere Associated With Dust Storms
Haider, S. A.; Venkateswara Rao, N.; Leelavathi, V. +2 more
The Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express spacecraft observes vertical echoes from the normal ionosphere and oblique echoes from ionization bulges. The peak frequencies of these two kinds of echoes are, in general, nearly equal. In the present study, we report the detection of oblique echoes…
Development of Hydrogen and Helium Proximity Zones around Quasars
Zheng, Wei; Meiksin, Avery; Syphers, David
Increasing evidence suggests that He II proximity profiles in the quasar spectra at z ∼ 3-4 are sensitive probes of quasar ages. But the development of their H I counterparts is difficult to trace and remains poorly constrained. We compare the UV spectra of 15 He II quasars with their high-resolution optical counterparts and find a significant cor…