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Diverse properties of Ly α emission in low-redshift compact star-forming galaxies with extremely high [O III]/[O II] ratios
Schaerer, D.; Thuan, T. X.; Izotov, Y. I. +5 more
We present observations with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope of eight compact star-forming galaxies at redshifts z = 0.02811-0.06540, with low oxygen abundances 12 + log(O/H) = 7.43-7.82 and extremely high emission-line flux ratios O32 = [O III] λ5007/[O II] λ3727 ∼ 22-39, aiming to study the propertie…
Atmospheric regimes and trends on exoplanets and brown dwarfs
Zhang, Xi
A planetary atmosphere is the outer gas layer of a planet. Besides its scientific significance among the first and most accessible planetary layers observed from space, it is closely connected with planetary formation and evolution, surface and interior processes, and habitability of planets. Current theories of planetary atmospheres were primaril…
The ARCiS framework for exoplanet atmospheres. Modelling philosophy and retrieval
Helling, Christiane; Min, Michiel; Ormel, Chris W. +2 more
Aims: We present ARCiS, a novel code for the analysis of exoplanet transmission and emission spectra. The aim of the modelling framework is to provide a tool able to link observations to physical models of exoplanet atmospheres.
Methods: The modelling philosophy chosen in this paper is to use physical and chemical models to constrain cer…
Strong biases in retrieved atmospheric composition caused by day-night chemical heterogeneities
Parmentier, Vivien; Leconte, Jérémy; Pluriel, William +1 more
Most planets currently amenable to transit spectroscopy are close enough to their host stars to exhibit a relatively strong day to night temperature gradient. For hot planets this leads to a chemical composition dichotomy between the two hemispheres. In the extreme case of ultra-hot Jupiters, some species, such as molecular hydrogen and water, are…
Dust-to-Gas and Refractory-to-Ice Mass Ratios of Comet 67P/Churyumov-Gerasimenko from Rosetta Observations
Pätzold, Martin; Choukroun, Mathieu; Thomas, Nicolas +9 more
This chapter reviews the estimates of the dust-to-gas and refractory-to-ice mass ratios derived from Rosetta measurements in the lost materials and the nucleus of 67P/Churyumov-Gerasimenko, respectively. First, the measurements by Rosetta instruments are described, as well as relevant characteristics of 67P. The complex picture of the activity of …
A kilonova associated with GRB 070809
Li, Xiang; Jin, Zhi-Ping; Covino, Stefano +4 more
For on-axis typical short gamma-ray bursts (sGRBs), the forward shock emission is usually so bright1,2 that it renders the identification of kilonovae (also known as macronovae)3-6 in the early afterglow (t < 0.5 d) phase rather challenging. This is why previously no thermal-like kilonova component has been identified at s…
Direct evidence for shock-powered optical emission in a nova
Wade, Gregg A.; Moffat, Anthony F. J.; Izzo, Luca +39 more
Classical novae are thermonuclear explosions that occur on the surfaces of white dwarf stars in interacting binary systems1. It has long been thought that the luminosity of classical novae is powered by continued nuclear burning on the surface of the white dwarf after the initial runaway2. However, recent observations of giga…
The Lowest-frequency Fast Radio Bursts: Sardinia Radio Telescope Detection of the Periodic FRB 180916 at 328 MHz
Palazzi, E.; Naletto, G.; Rea, N. +35 more
We report on the lowest-frequency detection to date of three bursts from the fast radio burst FRB 180916.J0158+65, observed at 328 MHz with the Sardinia Radio Telescope (SRT). The SRT observed the periodic repeater FRB 180916.J0158+65 for five days from 2020 February 20 to 24 during a time interval of active radio bursting, and detected the three …
Refining the Census of the Upper Scorpius Association with Gaia
Luhman, K. L.; Esplin, T. L.
We have refined the census of stars and brown dwarfs in the Upper Sco association (∼10 Myr, ∼145 pc) by (1) updating the selection of candidate members from our previous survey to include the high-precision astrometry from the second data release of Gaia, (2) obtaining spectra of a few hundred candidate members to measure their spectral types and …
The ASAS-SN catalogue of variable stars - V. Variables in the Southern hemisphere
Kochanek, C. S.; Stanek, K. Z.; Shappee, B. J. +13 more
The All-Sky Automated Survey for Supernovae (ASAS-SN) provides long baseline (∼4 yr) light curves for sources brighter than V ≲ 17 mag across the whole sky. As part of our effort to characterize the variability of all the stellar sources visible in ASAS-SN, we have produced ∼30.1 million V-band light curves for sources in the Southern hemisphere u…