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The High-mass Protostellar Population of a Massive Infrared Dark Cloud
Zhang, Yichen; Tan, Jonathan C.; Lim, Wanggi +3 more
We conduct a census of the high-mass protostellar population of the ∼70,000 M⊙ infrared dark cloud (IRDC) G028.37+00.07, identifying 35 sources based on their 70 µm emission, as reported in the Herschel Hi-GAL catalog of Molinari et al. We perform aperture photometry to construct spectral energy distributions, which are then fit w…
Short-term variability and mass loss in Be stars. V. Space photometry and ground-based spectroscopy of γ Cas
Handler, G.; Weiss, A.; Rivinius, Th. +9 more
Context. Be stars are physically complex systems that continue to challenge theory to understand their rapid rotation, complex variability, and decretion disks. γ Cassiopeiae (γ Cas) is one such star but is even more curious because of its unexplained hard thermal X-ray emission.
Aims: We aim to examine the optical variability of γ Cas and th…
A fresh look at the RR Lyrae population in the Draco dwarf spheroidal galaxy with Gaia
Garofalo, Alessia; Clementini, Gisella; Muraveva, Tatiana +1 more
We present a catalogue of 285 RR Lyrae stars (RRLs) in the Draco dwarf spheroidal (dSph) galaxy, obtained by combining data from a number of different surveys including the Data Release 2 (DR2) of the European Space Agency cornerstone mission Gaia. We have determined individual distances to the RRLs in our sample using for the first time a Gaia G-…
Gemini Near-Infrared Field Spectrograph Observations of the Seyfert 2 Galaxy Mrk 3: Feeding and Feedback on Galactic and Nuclear Scales
Kraemer, S. B.; Crenshaw, D. M.; Storchi-Bergmann, T. +10 more
We explore the kinematics of the stars, ionized gas, and warm molecular gas in the Seyfert 2 galaxy Mrk 3 (UGC 3426) on nuclear and galactic scales with Gemini Near-Infrared Field Spectrograph observations, previous Hubble Space Telescope data, and new long-slit spectra from the Apache Point Observatory (APO) 3.5 m telescope. The APO spectra are c…
Weak lensing shear estimation beyond the shape-noise limit: a machine learning approach
Merten, Julian; Ofek, Eran O.; Springer, Ofer M. +1 more
Weak lensing shear estimation typically results in per galaxy statistical errors significantly larger than the sought after gravitational signal of only a few per cent. These statistical errors are mostly a result of shape noise - an estimation error due to the diverse (and a priori unknown) morphology of individual background galaxies. These erro…
Occurrence rates of small planets from HARPS. Focus on the Galactic context
Mazeh, T.; Zucker, S.; Tal-Or, L. +4 more
Context. The stars in the Milky Way thin and thick disks can be distinguished by several properties such as metallicity and kinematics. It is not clear whether the two populations also differ in the properties of planets orbiting the stars. In order to study this, a careful analysis of both the chemical composition and mass detection limits is req…
Candidate Brown-dwarf Microlensing Events with Very Short Timescales and Small Angular Einstein Radii
Han, Cheongho; Udalski, Andrzej; Lee, Chung-Uk +65 more
Short-timescale microlensing events are likely to be produced by substellar brown dwarfs (BDs), but it is difficult to securely identify BD lenses based on only event timescales ${t}_{{\rm{E}}} because short-timescale events can also be produced by stellar lenses with high relative lens-source proper motions. In this paper, we report three strong …
Effects of density on the oxygen ionization equilibrium in collisional plasmas
Del Zanna, G.; Dufresne, R. P.; Badnell, N. R.
The ion populations most frequently adopted for diagnostics in collisional plasmas are derived from the density independent coronal approximation. In higher density, lower temperature conditions, ionization rates are enhanced once metastable levels become populated, and recombination rates are suppressed if ions recombine into Rydberg levels. As a…
Discovery of a Sirius-like binary system with a very strongly magnetic white dwarf. Binarity among magnetic white dwarfs
Landstreet, John D.; Bagnulo, Stefano
Non-interacting binary systems containing a magnetic white dwarf and a main-sequence star are considered extremely rare, perhaps non-existent. In the course of a search of magnetic fields in high-mass white dwarfs we have discovered a Sirius-like wide binary system composed of a main-sequence G0 star and an M ∼ 1.1 M⊙ white dwarf with a…
Understanding Saturn's interior from the Cassini Grand Finale gravity measurements
Ni, Dongdong
Context. Measurements of Saturn's gravity field by Cassini Grand Finale have been acquired with high precision. It has been demonstrated that the even gravitational harmonics J6-J10 have larger absolute values than the predictions by typical rigid-body interior models. A four-layer structure model, proposed to interpret Juno'…