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Stellar Characterization of M Dwarfs from the APOGEE Survey: A Calibrator Sample for M-dwarf Metallicities
Wanderley, Fábio; Cunha, Katia; Smith, Verne V. +18 more
We present spectroscopic determinations of the effective temperatures, surface gravities, and metallicities for 21 M dwarfs observed at high resolution (R ∼ 22,500) in the H band as part of the Sloan Digital Sky Survey (SDSS)-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. The atmospheric parameters and metallicities are…
[C II] 158 µm self-absorption and optical depth effects
Beuther, H.; Stutzki, J.; Güsten, R. +7 more
Context. The [C II] 158 µm far-infrared fine-structure line is one of the most important cooling lines of the star-forming interstellar medium (ISM). It is used as a tracer of star formation efficiency in external galaxies and to study feedback effects in parental clouds. High spectral resolution observations have shown complex structures in…
The Saga of M81: Global View of a Massive Stellar Halo in Formation
Bell, Eric F.; Monachesi, Antonela; Bailin, Jeremy +7 more
Recent work has shown that Milky Way-mass galaxies display an incredible range of stellar halo properties, yet the origin of this diversity is unclear. The nearby galaxy M81—currently interacting with M82 and NGC 3077—sheds unique light on this problem. We present a Subaru Hyper Suprime-Cam survey of the resolved stellar populations around M81, re…
Exploring AGN and star formation activity of massive galaxies at cosmic noon
Papovich, Casey; Finkelstein, Steven L.; Kirkpatrick, Allison +11 more
We investigate the relation between active galactic nucleus (AGN) and star formation (SF) activity at 0.5 < z < 3 by analysing 898 galaxies with X-ray luminous AGNs (LX > 1044 erg s-1) and a large comparison sample of ~320 000 galaxies without X-ray luminous AGNs. Our samples are selected from a large (11.…
Different Fates of Young Star Clusters after Gas Expulsion
Tang, Shih-Yun; Pang, Xiaoying; Pasquato, Mario +2 more
We identify structures of the young star cluster NGC 2232 in the solar neighborhood (323.0 pc) and a newly discovered star cluster, LP 2439 (289.1 pc). Member candidates are identified using the Gaia DR2 sky position, parallax, and proper-motion data by an unsupervised machine-learning method, STARGO. Member contamination from the Galactic disk is…
A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores
Louvet, F.; Hennebelle, P.; Guillet, V. +8 more
Context. Recent observational progress has challenged the dust grain-alignment theories used to explain the polarized dust emission routinely observed in star-forming cores.
Aims: In an effort to improve our understanding of the dust grain alignment mechanism(s), we have gathered a dozen ALMA maps of (sub)millimeter-wavelength polarized dust …
High-resolution UV/Optical/IR Imaging of Jupiter in 2016-2019
de Pater, Imke; Wong, Michael H.; Fletcher, Leigh N. +13 more
Imaging observations of Jupiter with high spatial resolution were acquired beginning in 2016, with a cadence of 53 days to coincide with atmospheric observations of the Juno spacecraft during each perijove pass. The Wide Field Camera 3 (WFC3) aboard the Hubble Space Telescope (HST) collected Jupiter images from 236 to 925 nm in 14 filters. The Nea…
The Ionizing Photon Production Efficiency (ξion) of Lensed Dwarf Galaxies at z ∼ 2
Richard, Johan; Siana, Brian; Freeman, William R. +5 more
We measure the ionizing photon production efficiency (ξion) of low-mass galaxies (107.8-109.8 M⊙) at 1.4 < z < 2.7 to better understand the contribution of dwarf galaxies to the ionizing background and reionization. We target galaxies that are magnified by strong-lensing galaxy clusters and use Kec…
Distinguishing between Wet and Dry Atmospheres of TRAPPIST-1 e and f
Rauer, H.; Sánchez-López, A.; López-Puertas, M. +7 more
The nearby TRAPPIST-1 planetary system is an exciting target for characterizing the atmospheres of terrestrial planets. The planets e, f, and g lie in the circumstellar habitable zone and could sustain liquid water on their surfaces. During the extended pre-main-sequence phase of TRAPPIST-1, however, the planets may have experienced extreme water …
Facing problems in the determination of stellar temperatures and gravities: Galactic globular clusters
Bonifacio, P.; Mucciarelli, A.
We analysed red giant branch stars in 16 Galactic globular clusters, computing their atmospheric parameters both from the photometry and from excitation and ionisation balances. The spectroscopic parameters are lower than the photometric ones and this discrepancy increases with decreasing metallicity, reaching differences of ~350 K in effective te…