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Xenon isotopes in 67P/Churyumov-Gerasimenko show that comets contributed to Earth's atmosphere
Wurz, P.; Altwegg, K.; Balsiger, H. +27 more
The origin of cometary matter and the potential contribution of comets to inner-planet atmospheres are long-standing problems. During a series of dedicated low-altitude orbits, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) on the Rosetta spacecraft analyzed the isotopes of xenon in the coma of comet 67P/Churyumov-Gerasimen…
The Stellar Initial Mass Function in Early-type Galaxies from Absorption Line Spectroscopy. III. Radial Gradients
van Dokkum, Pieter; Romanowsky, Aaron J.; Conroy, Charlie +2 more
There is good evidence that the centers of massive early-type galaxies have a bottom-heavy stellar initial mass function (IMF) compared to that of the Milky Way. Here we study the radial variation of the IMF within such galaxies, using a combination of high-quality Keck spectroscopy and a new suite of stellar population synthesis models that cover…
On the generation of solar spicules and Alfvénic waves
De Pontieu, B.; Martínez-Sykora, J.; Hansteen, V. H. +3 more
In the lower solar atmosphere, the chromosphere is permeated by jets known as spicules, in which plasma is propelled at speeds of 50 to 150 kilometers per second into the corona. The origin of the spicules is poorly understood, although they are expected to play a role in heating the million-degree corona and are associated with Alfvénic waves tha…
Powering prolonged hydrothermal activity inside Enceladus
Postberg, Frank; Sotin, Christophe; Čadek, Ondřej +4 more
Geophysical data from the Cassini spacecraft imply the presence of a global ocean underneath the ice shell of Enceladus1, only a few kilometres below the surface in the South Polar Terrain2-4. Chemical analyses indicate that the ocean is salty5 and is fed by ongoing hydrothermal activity6-8. In order to …
Geoeffective Properties of Solar Transients and Stream Interaction Regions
Balogh, A.; Kilpua, E. K. J.; von Steiger, R. +1 more
Interplanetary Coronal Mass Ejections (ICMEs), their possible shocks and sheaths, and co-rotating interaction regions (CIRs) are the primary large-scale heliospheric structures driving geospace disturbances at the Earth. CIRs are followed by a faster stream where Alfvénic fluctuations may drive prolonged high-latitude activity. In this paper we hi…
Paving the way for the JWST: witnessing globular cluster formation at z > 3
Castellano, M.; Pentericci, L.; Grillo, C. +17 more
We report on five compact, extremely young (<10 Myr) and blue (βUV < -2.5, Fλ = λβ) objects observed with VLT/Multi Unit Spectroscopic Explorer at redshifts 3.1169 and 3.235, in addition to three objects at z = 6.145. These sources are strongly magnified (3-40 times) by the Hubble Frontier Field galaxy cluste…
Comoving Stars in Gaia DR1: An Abundance of Very Wide Separation Comoving Pairs
Hogg, David W.; Morton, Timothy D.; Price-Whelan, Adrian M. +2 more
The primary sample of the Gaia Data Release 1 is the Tycho-Gaia Astrometric Solution (TGAS): ≈2 million Tycho-2 sources with improved parallaxes and proper motions relative to the initial catalog. This increased astrometric precision presents an opportunity to find new binary stars and moving groups. We search for high-confidence comoving pairs of…
Machine-learned Identification of RR Lyrae Stars from Sparse, Multi-band Data: The PS1 Sample
Grebel, Eva K.; Magnier, Eugene A.; Rix, Hans-Walter +16 more
RR Lyrae stars may be the best practical tracers of Galactic halo (sub-)structure and kinematics. The PanSTARRS1 (PS1) 3π survey offers multi-band, multi-epoch, precise photometry across much of the sky, but a robust identification of RR Lyrae stars in this data set poses a challenge, given PS1's sparse, asynchronous multi-band light curves (≲ 12 …
Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles
Shi, Xian; Blum, Jürgen; Della Corte, Vincenzo +19 more
The processes that led to the formation of the planetary bodies in the Solar system are still not fully understood. Using the results obtained with the comprehensive suite of instruments onboard the European Space Agency's Rosetta mission, we present evidence that comet 67P/Churyumov-Gerasimenko likely formed through the gentle gravitational colla…
The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars
Cargile, Phillip A.; Morton, Timothy D.; Fulton, Benjamin J. +11 more
We present stellar and planetary properties for 1305 Kepler Objects of Interest hosting 2025 planet candidates observed as part of the California-Kepler Survey. We combine spectroscopic constraints, presented in Paper I, with stellar interior modeling to estimate stellar masses, radii, and ages. Stellar radii are typically constrained to 11%, comp…