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Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. IV. The Kinematic Signature of the Galactic Warp
Wang, H. -F.; Huang, Y.; Chen, B. -Q. +5 more
Using a sample of nearly 140,000 red clump stars selected from the LAMOST and Gaia Galactic surveys, we have mapped mean vertical velocity $\overline{{V}_{z}}$ in the X-Y plane for a large volume of the Galactic disk (6 < R < 16 kpc; -20 < φ < 50°; $| Z| \lt 1$ kpc). A clear signature where $\overline{{V}_{z}}$ increases with R is dete…
Low-cost precursor of an interstellar mission
Heller, René; Hippke, Michael; Kervella, Pierre +1 more
The solar photon pressure provides a viable source of thrust for spacecraft in the solar system. Theoretically it could also enable interstellar missions, but an extremely small mass per cross section area is required to overcome the solar gravity. We identify aerographite, a synthetic carbon-based foam with a density of 0.18 kg m-3 (15…
Improved Infrared Photometry and a Preliminary Parallax Measurement for the Extremely Cold Brown Dwarf CWISEP J144606.62-231717.8
Meisner, Aaron M.; Cushing, Michael C.; Kirkpatrick, J. Davy +6 more
We present follow-up Spitzer observations at 3.6 µm (ch1) and 4.5 µm (ch2) of CWISEP J144606.62-231717.8, one of the coldest known brown dwarfs in the solar neighborhood. This object was found by mining the Wide-field Infrared Survey Explorer (WISE) and NEOWISE data via the CatWISE Preliminary Catalog by Meisner et al., where an initia…
First detection of NHD and ND2 in the interstellar medium. Amidogen deuteration in IRAS 16293-2422
Caselli, P.; Sipilä, O.; Bizzocchi, L. +7 more
Context. Deuterium fractionation processes in the interstellar medium (ISM) have been shown to be highly efficient in the family of nitrogen hydrides. To date, observations have been limited to ammonia (NH2D, NHD2, ND3) and imidogen radical (ND) isotopologues.
Aims: We want to explore the high-frequency window…
Evidence for Disk Truncation at Low Accretion States of the Black Hole Binary MAXI J1820+070 Observed by NuSTAR and XMM-Newton
Fabian, Andrew C.; Walton, Dominic J.; Hare, Jeremy +3 more
We present results from NuSTAR and XMM-Newton observations of the new black hole X-ray binary MAXI J1820+070 at low accretion rates (below 1% of the Eddington luminosity). We detect a narrow Fe Kα emission line, in contrast to the broad and asymmetric Fe Kα line profiles commonly present in black hole binaries at high accretion rates. The narrow l…
White Dwarfs in the Era of the LSST and Its Synergies with Space-based Missions
McConnachie, Alan W.; Côté, Patrick; Fantin, Nicholas J.
With the imminent start of the Legacy Survey for Space and Time (LSST) at the Vera C. Rubin Observatory and several new space telescopes expected to begin operations later in this decade, both time-domain and wide-field astronomy are on the threshold of a new era. In this paper, we use a new multicomponent model for the distribution of white dwarf…
The power of coordinate transformations in dynamical interpretations of Galactic structure
Hogg, David W.; Kawata, Daisuke; Johnston, Kathryn V. +3 more
Gaia DR2 has provided an unprecedented wealth of information about the positions and motions of stars in our Galaxy and has highlighted the degree of disequilibria in the disc. As we collect data over a wider area of the disc, it becomes increasingly appealing to start analysing stellar actions and angles, which specifically label orbit space, ins…
Piercing through Highly Obscured and Compton-thick AGNs in the Chandra Deep Fields. II. Are Highly Obscured AGNs the Missing Link in the Merger-triggered AGN-Galaxy Coevolution Models?
Yang, Guang; Brandt, William N.; Comastri, Andrea +12 more
By using a large, highly obscured ( ${N}_{{\rm{H}}}\gt {10}^{23}\ {\mathrm{cm}}^{-2}$ ) active galactic nucleus (AGN) sample (294 sources at z ∼ 0-5) selected from detailed X-ray spectral analyses in the deepest Chandra surveys, we explore distributions of these X-ray sources in various optical/infrared/X-ray color-color diagrams and their host-ga…
Systematics and accuracy of VLBI astrometry: A comparison with Gaia Data Release 2
Liu, N.; Zhu, Z.; Liu, J. -C. +1 more
Context. The third generation of the ICRF - ICRF3 - was published in 2018. This new fundamental catalog provides radio source positions measured independently at three bands: S/X, K, and X/Ka, representing three independent radio celestial frames which altogether constitute a multi-frequency ICRF.
Aims: We aim to investigate the overall prope…
The M31/M33 tidal interaction: a hydrodynamic simulation of the extended gas distribution
Li, Di; Bland-Hawthorn, Joss; Tepper-García, Thor
We revisit the orbital history of the Triangulum galaxy (M33) around the Andromeda galaxy (M31) in view of the recent Gaia Data Release 2 proper motion measurements for both Local Group galaxies. Earlier studies consider highly idealized dynamical friction, but neglect the effects of dynamical mass loss. We show the latter process to be important …