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Detection of Hα emission from PZ Telescopii B using SPHERE/ZIMPOL
Henning, Thomas; Musso Barcucci, Arianna; Launhardt, Ralf +6 more
Hα is a powerful tracer of accretion and chromospheric activity, which has been detected in the case of young brown dwarfs and even recently in planetary mass companions (e.g. PDS70 b and c). Hα detections and characterisation of brown dwarf and planet companions can further our knowledge of their formation and evolution, and expanding such a samp…
SN 2016B a.k.a. ASASSN-16ab: a transitional Type II supernova
Pandey, S. B.; Benetti, S.; Kumar, Brajesh +12 more
We present photometry, polarimetry, and spectroscopy of the Type II supernova ASASSN-16ab/SN 2016B in PGC 037392. The photometric and spectroscopic follow-up commenced about 2 weeks after shock breakout and continued until nearly 6 months. The light curve of SN 2016B exhibits intermediate properties between those of Type IIP and IIL. The early dec…
Kinematics and dynamics of the luminous infrared galaxy pair NGC 5257/58 (Arp 240)
Rosado, M.; Amram, P.; Fuentes-Carrera, I. +6 more
Context. Encounters between galaxies modify their morphology, kinematics, and star formation history. The relation between these changes and external perturbations is not straightforward. The great number of parameters involved requires both the study of large samples and individual encounters where particular features, motions, and perturbations …
On ancient solar-type stars
Fuhrmann, Klaus; Chini, Rolf
We describe a survey of ancient solar-type stars down to main-sequence effective temperatures Teff ≥ 5300 K and within 42 pc of the Sun. The underlying Gaia-based, volume-complete parent sample consists of 1633 sources, dominated by Population I. The design of the survey is such that around 130 sources are expected to be members of Popu…
Acceleration of plasma in current sheet during substorm dipolarizations in the Earth's magnetotail: Comparison of different mechanisms
Parkhomenko, Elena I.; Malova, Helmi V.; Grigorenko, Elena E. +6 more
This work is devoted to the investigation of particle acceleration during magnetospheric dipolarizations. A numerical model is presented taking into account the four scenarios of plasma acceleration that can be realized: (A) total dipolarization with characteristic time scales of ≈3 min; (B) single peak value of the normal magnetic component …
DS Andromedae: A Detached Eclipsing Double-lined Spectroscopic Binary in the Galactic Cluster NGC 752
Frandsen, S.; Milone, E. F.; Schiller, S. J. +1 more
The Wilson-Devinney program has been used to analyze well-calibrated photometric and new radial velocity data to determine the properties and distance of DS Andromedae, a 1.01 day period, double-lined, totally eclipsing binary system of early-F spectral type and a likely member of the intermediate-age open cluster NGC 752. The determinations of ma…
On the Properties of the Galactic Dust Layer within 700 pc of the Sun
Gontcharov, G. A.
We compare the spatial stellar color variations with our three-dimensional analytical model of the spatial dust distribution to refine the properties of the dust layer in Galactic solar neighborhoods. We use a complete sample of 93 992 clump giants with a small admixture of branch giants from the Gaia DR2 catalogue in a spatial cylinder with a rad…
Poisson vs. Gaussian statistics for sparse X-ray data: Application to the soft X-ray spectrometer
Eckart, Megan E.; Kelley, Richard L.; Kilbourne, Caroline A. +8 more
Reliable results when fitting X-ray data require proper consideration of the statistics involved. We probe the impact of Gaussian versus Poisson statistics at low count levels using both the standard χ2 method and maximum likelihood based on Poisson (C) statistics. The difference is studied and quantified through simulated spectra with …
Radio observations of evaporating objects in the Cygnus OB2 region
del Palacio, S.; Fernández-López, M.; Ishwara-Chandra, C. H. +2 more
We present observations of the Cygnus OB2 region obtained with the Giant Metrewave Radio Telescope (GMRT) at frequencies of 325 and 610 MHz. In this contribution we focus on the study of proplyd-like objects (also known as free-floating evaporating gas globules or frEGGs) that typically show an extended cometary morphology. We identify eight objec…
Strongly magnetic Ap stars in the Gaia DR2 Hertzsprung-Russell diagram . I. Selecting the most reliable astrometric and photometric data
Hubrig, S.; Chojnowski, S. Drew; Scholz, R. -D.
Context. Knowing the distribution of strongly magnetic Ap stars in the Hertzsprung-Russell diagram (HRD) allows us to study the evolution of their magnetic fields across the main sequence (MS). With a newly extended Ap star sample from APOGEE and available Gaia DR2 data, we can now critically review the results of previous studies based on HIPPARC…