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The 11 yr of low activity of the magnetar XTE J1810-197
Pintore, Fabio; Mereghetti, Sandro; Esposito, Paolo +5 more
In 2003, the magnetar XTE J1810-197 started an outburst that lasted until early 2007. In the following 11 yr, the source stayed in a quiescent/low-activity phase. XTE J1810-197 is one of the closest magnetars, hence its X-ray properties can be studied in detail even in quiescence and an extended monitoring has been carried out to study its long-te…
A Search for Water Vapor Plumes on Europa using SOFIA
Sparks, W. B.; Dello Russo, N.; Hand, K. P. +8 more
We present mid-infrared Stratospheric Observatory for Infrared Astronomy (SOFIA)/Echelon Cross Echelle Spectrograph (EXES) spectroscopy of Europa, seeking direct evidence of the presence of water vapor arising from plumes venting from the surface. We place quantitatively useful upper limits on the strength of water vibrational-rotational emission …
Comprehensive abundance analysis of red giants in the open clusters Stock 2, NGC 2168, 6475, 6991, and 7762
Lambert, David L.; Reddy, Arumalla B. S.
We have analysed high-dispersion Echelle spectra (R = 60 000) of red giant members of five open clusters to derive abundances for many elements from Na to Eu. The [Fe/H] values are -0.06 ± 0.03 for Stock 2, -0.11 ± 0.03 for NGC 2168, -0.01 ± 0.03 for NGC 6475, 0.00 ± 0.03 for NGC 6991, and -0.07 ± 0.03 for NGC 7662. Sodium is enriched in the giant…
Characterising the high-mass star forming filament G351.776-0.527 with Herschel and APEX dust continuum and gas observations
König, C.; Menten, K. M.; Testi, L. +13 more
G351.776-0.527 is among the most massive, closest, and youngest filaments in the inner Galactic plane and therefore it is an ideal laboratory to study the kinematics of dense gas and mass replenishment on a large scale. In this paper, we present far-infrared and submillimetre wavelength continuum observations combined with spectroscopic C18
Lifetimes and Occurrence Rates of Dark Vortices on Neptune from 25 Years of Hubble Space Telescope Images
Wong, Michael H.; Simon, Amy A.; Hsu, Andrew I.
We scoured the full set of blue-wavelength Hubble Space Telescope images of Neptune, finding one additional dark spot in new Hubble data beyond those discovered in 1989, 1994, 1996, and 2015. We report the complete disappearance of the SDS-2015 dark spot, using new Hubble data taken on 2018 September 9-10, as part of the Outer Planet Atmospheres L…
The HST lightcurve of (486958) 2014 MU69
Stern, S. A.; Buie, M. W.; Spencer, J. R. +6 more
We report Hubble Space Telescope (HST) lightcurve observations of the New Horizons spacecraft encounter Kuiper Belt object (KBO) (486958) 2014 MU69 acquired near opposition in July 2017. In order to plan the optimum flyby sequence the New Horizons mission planners needed to learn as much as possible about the target in advance of the en…
Genus Statistic Applied to the X-Ray Remnant of SN 1572: Clues to the Clumpy Ejecta Structure of Type Ia Supernovae
Sato, Toshiki; Hughes, John P.; Williams, Brian J. +1 more
Clumpy structures are a common feature in X-ray images of young Type Ia supernova remnants (SNRs). Although the precise origin of such clumps remains unclear, there are three generic possibilities: clumpiness imposed during the explosion, hydrodynamic instabilities that act during the remnant’s evolution, and preexisting structures in the ambient …
Exoplanet transits with next-generation radio telescopes
Pope, Benjamin J. S.; Withers, Paul; Vogt, Marissa F. +1 more
Nearly everything we know about extrasolar planets to date comes from optical astronomy. While exoplanetary aurorae are predicted to be bright at low radio frequencies (<1 GHz), we consider the effect of an exoplanet transit on radio emission from the host star. As radio emission from solar-like stars is concentrated in active regions, a planet…
A Comparison of the X-Ray Properties of FU Ori-type Stars to Generic Young Stellar Objects
Hillenbrand, Lynne A.; Kuhn, Michael A.
Like other young stellar objects (YSOs), FU Ori-type stars have been detected as strong X-ray emitters. However, little is known about how the outbursts of these stars affect their X-ray properties. We assemble available X-ray data from XMM-Newton and Chandra observations of 16 FU Ori stars, including a new XMM-Newton observation of Gaia 17bpi dur…
Solar microflares: a case study on temperatures and the Fe XVIII emission
Del Zanna, G.; Mitra-Kraev, U.
In this paper, we discuss the temperature distribution and evolution of a microflare, simultaneously observed by Hinode's X-Ray Telescope (XRT), its Extreme Ultraviolet Imaging Spectrometer (EIS), as well as the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory (SDO). Using EIS lines, we find that during peak emission the …