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Metallic-line Stars Identified from Low-resolution Spectra of LAMOST DR5
Qin, Li; Luo, A. -Li; Hou, Wen +6 more
The Large Sky Area Multi-Object Fibre Spectroscopic Telescope data release 5 (DR5) released more than 200,000 low-resolution spectra of early-type stars with a signal-to-noise ratio > 50. The search for metallic-line (Am) stars in such a large database and a study of their statistical properties are presented in this paper. Six machine-learning…
Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. III. A New Velocity Substructure and Time Stamps of the Galactic Disk Asymmetry in the Disk between 12 and 15 kpc
Huang, Y.; Chen, B. -Q.; Wang, C. +11 more
We investigate the three-dimensional asymmetrical kinematics and present time stamps of the Milky Way disk between Galactocentric distances of R = 12 and 15 kpc, using red clump stars selected from the LAMOST Galactic survey, also with proper motion measurements provided by the Gaia DR2. We discover velocity substructure above the Galactic plane c…
Gaia-DR2 distance to the W3 Complex in the Perseus Arm
Damineli, Augusto; Navarete, Felipe; Galli, Phillip A. B.
The Perseus Arm is the closest Galactic spiral arm from the Sun, offering an excellent opportunity to study in detail its stellar population. However, its distance has been controversial with discrepancies by a factor of two. Kinematic distances are in the range 3.9-4.2 kpc as compared to 1.9-2.3 kpc from spectrophotometric and trigonometric paral…
Exposing the plural nature of molecular clouds. Extracting filaments and the cosmic infrared background against the true scale-free interstellar medium
Schneider, N.; Bontemps, S.; Elia, D. +2 more
We present the Multiscale non-Gaussian Segmentation (MnGSeg) analysis technique. This wavelet-based method combines the analysis of the probability distribution function (PDF) of map fluctuations as a function of spatial scales and the power spectrum analysis of a map. This technique allows us to extract the non-Gaussianities identified in the mul…
Observations of Binary Stars with the Differential Speckle Survey Instrument. VIII. Measures of Metal-poor and Triple Stars from 2015 to 2018
Kane, Stephen R.; Howell, Steve B.; Hirsch, Lea A. +15 more
We present 248 speckle observations of 43 binary and 19 trinary star systems chosen to make progress in two main areas of investigation: the fundamental properties of metal-poor stars and star formation mechanisms. The observations were taken at the Gemini North and South telescopes during the period 2015 July to 2018 April, mainly with the Differ…
Asteroseismology of the Hyades red giant and planet host ɛ Tauri
Christensen-Dalsgaard, J.; Andersen, M. F.; Grundahl, F. +23 more
Context. Asteroseismic analysis of solar-like stars allows us to determine physical parameters such as stellar mass, with a higher precision compared to most other methods. Even in a well-studied cluster such as the Hyades, the masses of the red giant stars are not well known, and previous mass estimates are based on model calculations (isochrones…
Semi-empirical model atmospheres for the chromosphere of the sunspot penumbra and umbral flashes
Rouppe van der Voort, Luc; Henriques, Vasco M. J.; Bose, Souvik +1 more
Context. The solar chromosphere and the lower transition region are believed to play a crucial role in the heating of the solar corona. Models that describe the chromosphere (and the lower transition region), accounting for its highly dynamic and structured character are, so far, found to be lacking. This is partly due to the breakdown of complete…
TOI-216b and TOI-216 c: Two Warm, Large Exoplanets in or Slightly Wide of the 2:1 Orbital Resonance
Latham, David W.; Esquerdo, Gilbert A.; Zhou, George +32 more
Warm, large exoplanets with 10-100 day orbital periods pose a major challenge to our understanding of how planetary systems form and evolve. Although high eccentricity tidal migration has been invoked to explain their proximity to their host stars, a handful reside in or near orbital resonance with nearby planets, suggesting a gentler history of i…
Prevalence of neutral gas in centres of merging galaxies-II: nuclear H I and multiwavelength properties
Srianand, R.; Gupta, N.; Dutta, R.
Using a sample of 38 radio-loud galaxy mergers at z ≤ 0.2, we confirm the high detection rate (∼84 per cent) of H I 21-cm absorption in mergers, which is significantly higher (∼4 times) than in non-mergers. The distributions of the H I column density [N({H I})] and velocity shift of the absorption with respect to the systemic redshift of the galax…
Stellar and Dust Properties of a Complete Sample of Massive Dusty Galaxies at 1 ≤ z ≤ 4 from MAGPHYS Modeling of UltraVISTA DR3 and Herschel Photometry
Martis, Nicholas S.; Muzzin, Adam; Brammer, Gabriel +5 more
We investigate the stellar and dust properties of massive (log M */M ⊙ ≥ 10.5) and dusty (A V ≥ 1) galaxies at 1 ≤ z ≤ 4 by modeling their spectral energy distributions (SEDs) obtained from the combination of UltraVISTA DR3 photometry and Herschel PACS-SPIRE data using MAGPHYS. Although the rest-frame U-V versus …