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Cometary Activity Discovered on a Distant Centaur: A Nonaqueous Sublimation Mechanism
Chandler, Colin Orion; Trujillo, Chadwick A.; Oldroyd, William J. +2 more
Centaurs are minor planets thought to have originated in the outer solar system region known as the Kuiper Belt. Active Centaurs enigmatically display comet-like features (e.g., tails, comae) even though they orbit in the gas giant region where it is too cold for water to readily sublimate. Only 18 active Centaurs have been identified since 1927 a…
Coronal Photopolarimetry with the LASCO-C2 Coronagraph over 24 Years [1996 - 2019]
Lamy, Philippe; Gilardy, Hugo; Llebaria, Antoine +3 more
We present an in-depth characterization of the polarimetric channel of the Large-Angle Spectrometric COronagraph/LASCO-C2 onboard the Solar and Heliospheric Observatory (SOHO). The polarimetric analysis of the white-light images makes use of polarized sequences composed of three images obtained though three polarizers oriented at +60∘, …
Abundance analyses of Li-enriched and normal giants in the GALAH survey
Lambert, David L.; Deepak; Reddy, Bacham E.
Compositions of lithium-enriched and normal giants among the GALAH survey are compared. Except for Li, the only detectable abundance difference between lithium-enriched and normal giants among the investigated elements from carbon to europium occurs for carbon. Among Li-rich giants with A(Li) = 1.8-3.1, the C deficiency is very similar to that rep…
The MUSE view of the planetary nebula NGC 3132
Monreal-Ibero, Ana; Walsh, Jeremy R.
Aims: Two-dimensional spectroscopic data for the whole extent of the NGC 3132 planetary nebula have been obtained. We deliver a reduced data-cube and high-quality maps on a spaxel-by-spaxel basis for the many emission lines falling within the Multi-Unit Spectroscopic Explorer (MUSE) spectral coverage over a range in surface brightness >100…
Detailed Imaging of Coronal Rays with the Parker Solar Probe
Vourlidas, Angelos; Poirier, Nicolas; Kouloumvakos, Athanasios +13 more
The Wide-field Imager for Solar PRobe (WISPR) obtained the first high-resolution images of coronal rays at heights below 15 R⊙ when the Parker Solar Probe (PSP) was located inside 0.25 au during the first encounter. We exploit these remarkable images to reveal the structure of coronal rays at scales that are not easily discernible in im…
Analysis of Cassini radio tracking data for the construction of INPOP19a: A new estimate of the Kuiper belt mass
Laskar, J.; Fienga, A.; Iess, L. +3 more
Context. Recent discoveries of new trans-Neptunian objects have greatly increased the attention by the scientific community to this relatively unknown region of the solar system. The current level of precision achieved in the description of planet orbits has transformed modern ephemerides in the most updated tools for studying the gravitational in…
Incoherent fast variability of X-ray obscurers. The case of NGC 3783
Kaastra, J. S.; Kriss, G. A.; Arav, N. +22 more
Context. Obscuration events caused by outflowing clumps or streams of high column density and low ionised gas, shown to absorb the X-ray continuum heavily, have been witnessed across a number of Seyfert galaxies.
Aims: We report on the X-ray spectral-timing analysis of the December 2016 obscuration event in NGC 3783, which was aimed at probin…
Abell 30 - A binary central star among the born-again planetary nebulae
Jones, David; Jacoby, George H.; Hillwig, Todd C.
Eight planetary nebulae have been identified as 'born-again', a class of object typified by knotty secondary ejecta having low masses (${\sim}10^{-4}$ M⊙) with nearly no hydrogen. Abell 30, the archetype of the class, also belongs to a small subset of planetary nebulae that exhibit extreme abundance discrepancy factors (where Abell 30 i…
The State of the Heliosphere Revealed by Limb-halo Coronal Mass Ejections in Solar Cycles 23 and 24
Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji
We compare the properties of halo coronal mass ejections (CMEs) that originate close to the limb (within a central meridian distance range of 60°-∼90°) during solar cycles 23 and 24 to quantify the effect of the heliospheric state on CME properties. There are 44 and 38 limb halos in cycles 23 and 24, respectively. Normalized to the cycle-averaged …
New Beta Cephei Stars from the KELT Project
Pepper, Joshua; Stassun, Keivan G.; Siverd, Robert J. +9 more
We present the results of a search for Galactic β Cephei stars, which are massive pulsating stars with both pressure modes and mixed modes. Thus, these stars can serve as benchmarks for seismological studies of the interiors of massive stars. We conducted the search by performing a frequency analysis on the optical light curves of known O- and B-t…