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Observations of the Solar F-Corona from Space
Llebaria, A.; Lamy, P. L.; Gilardy, H.
We present a review of the observations of the solar F-corona from space with a special emphasis of the 25 years of continuous monitoring achieved by the LASCO-C2 and C3 coronagraphs. Our work includes images obtained by the navigation cameras of the Clementine spacecraft, the SECCHI/HI-1A heliospheric imager onboard STEREO-A, and the Wide Field I…
Effect of an Interplanetary Coronal Mass Ejection on Saturn's Radio Emission
Jackman, C. M.; Cecconi, B.; Sánchez-Cano, B. +2 more
The Saturn Kilometric Radiation (SKR) was observed for the first time during the flyby of Saturn by the Voyager spacecraft in 1980. These radio emissions, in the range of a few kHz to 1 MHz, are emitted by electrons travelling around auroral magnetic field lines. Their study is useful to understand the variability of a magnetosphere and its coupli…
Two-point Separation Functions for Modeling Wide Binary Systems in Nearby Dwarf Galaxies
Peñarrubia, Jorge; Koposov, Sergey E.; Walker, Matthew G. +1 more
We use a geometric method to derive (two-dimensional) separation functions among pairs of objects within populations of specified position function ${dN}/d{\boldsymbol{R}}$ . We present analytic solutions for separation functions corresponding to a uniform surface density within a circular field, a Plummer sphere (viewed in projection), and the mi…
Interstellar Extinction and Polarization of Stars in the Open Cluster NGC 6709
Topasna, G. A.; Kaltcheva, N. T.; Gibson, S. D.
We present BVRI polarimetric measurements of 23 stars in the direction of the open cluster NGC 6709. Fifteen stars display wavelength-dependence of polarization which is typically due to selective extinction in the interstellar medium and could be fitted to the Serkwoski equation. Based on these stars, we obtained an average maximum degree of pola…
The neutron-capture and α-elements abundance ratios scatter in old stellar populations: cosmological simulations of the stellar halo
Chiappini, Cristina; Cescutti, Gabriele; Scannapieco, Cecilia
We investigate the origin of the abundance ratios and scatter of the neutron-capture elements Sr, Ba, and Eu in the stellar halo of a Milky Way-mass galaxy formed in a hydrodynamical cosmological simulation, and compare them with those of α elements. For this, we implement a novel treatment for chemical enrichment of Type II supernovae that consid…
Understanding High-Energy (UV and X-ray) Emission from AGB Stars—Episodic Accretion in Binary Systems
Sanz-Forcada, Jorge; Sahai, Raghvendra; Ortiz, Roberto +2 more
X-ray surveys of UV-emitting AGB stars show that ∼40% of objects with FUV emission and GALEX FUV/NUV flux ratio Rfuv/nuv ∼> 0.2 (fuvAGB stars) have variable X-ray emission characterized by very high temperatures (Tx∼35–160 MK) and luminosities (Lx∼0.002–0.2 L⊙), indicating the presence of accretion associated with a close binary companion. Howe…
Massive Molecular Gas Reservoir in a Luminous Submillimeter Galaxy during Cosmic Noon
Cooray, A.; Marchetti, L.; Nayyeri, H. +11 more
We present multiband observations of an extremely dusty star-forming lensed galaxy (HERS1) at z = 2.553. High-resolution maps of HST/WFC3, SMA, and ALMA show a partial Einstein ring with a radius of ~3″. The deeper HST observations also show the presence of a lensing arc feature associated with a second lens source, identified to be at the same re…
Multi-passband Observations of a Solar Flare over the He I 10830 Å line
Polito, Vanessa; Xu, Yan; Cao, Wenda +5 more
This study presents a C3.0 flare observed by the Big Bear Solar Observatory/Goode Solar Telescope (GST) and Interface Region Imaging Spectrograph (IRIS) on 2018 May 28 around 17:10 UT. The Near-Infrared Imaging Spectropolarimeter of GST was set to spectral imaging mode to scan five spectral positions at ±0.8, ±0.4 Å and line center of He I 10830 Å…
Evolution of a dark vortex on Neptune with transient secondary features
de Pater, Imke; Wong, Michael H.; Irwin, Patrick G. J. +8 more
Dark spots on Neptune observed by Voyager and the Hubble Space Telescope are thought to be anticyclones with lifetimes of a few years, in contrast with very long-lived anticyclones in Jupiter and Saturn. The full life cycle of any Neptune dark spot has not been captured due to limited temporal coverage, but our Hubble observations of a recent feat…
The recent star formation history of NGC 628 on resolved scales
Saintonge, Amélie; De Looze, Ilse; Decleir, Marjorie +1 more
Star formation histories (SFHs) are integral to our understanding of galaxy evolution. We can study recent SFHs by comparing the star formation rate (SFR) calculated using different tracers, as each probes a different time-scale. We aim to calibrate a proxy for the present-day rate of change in SFR, dSFR/dt, which does not require full spectral en…