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The Green Bank Ammonia Survey: A Virial Analysis of Gould Belt Clouds in Data Release 1
Caselli, Paola; Chen, Mike; Di Francesco, James +14 more
We perform a virial analysis of starless dense cores in three nearby star-forming regions: L1688 in Ophiuchus, NGC 1333 in Perseus, and B18 in Taurus. Our analysis takes advantage of comprehensive kinematic information for the dense gas in all of these regions made publicly available through the Green Bank Ammonia Survey Data Release 1, which is u…
Large-amplitude Quasiperiodic Pulsations as Evidence of Impulsive Heating in Hot Transient Loop Systems Detected in the EUV with SDO/AIA
Testa, Paola; Petralia, Antonino; Reale, Fabio +1 more
Short heat pulses can trigger plasma pressure fronts inside closed magnetic tubes in the corona. The alternation of condensations and rarefactions from the pressure modes drive large-amplitude pulsations in the plasma emission. Here we show the detection of such pulsations along magnetic tubes that brighten transiently in the hot 94 Å EUV channel …
Dusk over dawn O2 asymmetry in Europa's near-surface atmosphere
Johnson, Robert E.; Chaufray, Jean-Yves; Oza, Apurva V. +4 more
The evolution of Europa's water-product exosphere over its 85-h day, based on current models, has not been shown to exhibit any diurnal asymmetries. Here we simulate Europa's exosphere using a 3-D Monte Carlo routine including, for the first time, the role of Europa's rotation on the evolution of exospheric molecules tracked throughout the orbit. …
How Comets Work
Blum, J.; Fulle, M.; Rotundi, A.
Two major questions regarding comets have been up to now far from any solution. (i) How is it possible that water-ice sublimation from the nucleus surface does not lead to an insulating crust, stopping every gas and dust ejection within a few days? (ii) How is it possible that the gas flow crossing the refractory surface crust ejects dust particle…
Orbital Motion of the Wide Planetary-mass Companion GSC 6214-210 b: No Evidence for Dynamical Scattering
Rizzuto, Aaron C.; Dupuy, Trent J.; Ireland, Michael J. +5 more
Direct-imaging exoplanet surveys have discovered a class of 5-20 {M}Jup} substellar companions at separations >100 au from their host stars, which present a challenge to planet and star formation models. Detailed analysis of the orbital architecture of these systems can provide constraints on possible formation mechanisms, including …
Velocity profiles of [CII], [CI], CO, and [OI] and physical conditions in four star-forming regions in the Large Magellanic Cloud
Hughes, Annie; Güsten, Rolf; Okada, Yoko +4 more
Aims: The aim of our study is to investigate the physical properties of the star-forming interstellar medium (ISM) in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. The LMC provides a unique local template to bridge studies in the Galaxy and high redshift galaxies because of its low m…
Red and Reddened: Ultraviolet through Near-infrared Observations of Type Ia Supernova 2017erp
Wang, Lifan; Hsiao, E. Y.; Ruiter, Ashley J. +22 more
We present space-based ultraviolet/optical photometry and spectroscopy with the Swift Ultra-Violet/Optical Telescope and Hubble Space Telescope (HST), respectively, along with ground-based optical photometry and spectroscopy and near-infrared spectroscopy of supernova SN 2017erp. The optical light curves and spectra are consistent with a normal SN…
Kiloparsec-Scale Variations in the Star Formation Efficiency of Dense Gas: The Antennae Galaxies (NGC 4038/39)
Wilson, Christine D.; Bemis, Ashley
We study the relationship between dense gas and star formation in the Antennae galaxies by comparing Atacama large millimeter/submillimeter array (ALMA) observations of dense-gas tracers (HCN, HCO+, and HNC J = 1-0) with the total infrared luminosity (L TIR) calculated using data from the Herschel Space Observatory and the Sp…
Age gradients throughout the Galaxy with long-period variables
Evans, N. W.; Belokurov, V.; Grady, J.
We assemble the largest sample of oxygen-rich (O-rich) Miras and associated long-period variables (LPVs) to date and highlight their importance for age dating the components of the Galaxy. Using data from the Catalina Surveys and the All Sky Automated Survey for Supernovae, we extract a clean sample of ∼2200 O-rich LPVs, stretching from the Galact…
Calibrating Mg II-based Black Hole Mass Estimators with Hβ Reverberation Measurements
Park, Daeseong; Woo, Jong-Hak; Bahk, Hyeonguk
We present the new calibration of black hole mass ({M}BH}) estimators based on the Mg II λ2798 broad emission line using the Hβ reverberation-mapped (RM) sample of 31 active galactic nuclei (AGNs) that have high-quality UV spectra. The updated and enlarged sample at redshift z < 0.16 covers a large dynamic range in {M}BH} …