Search Publications
Visual Orbits of Spectroscopic Binaries with the CHARA Array. I. HD 224355
Gies, Douglas R.; Lester, Kathryn V.; Monnier, John D. +5 more
We present the visual orbit of the double-lined spectroscopic binary HD 224355 from interferometric observations with the CHARA Array, as well as an updated spectroscopic analysis using echelle spectra from the Apache Point Observatory 3.5 m telescope. By combining the visual and spectroscopic orbital solutions, we find the binary components to ha…
High-fidelity Imaging of the Inner AU Mic Debris Disk: Evidence of Differential Wind Sculpting?
Stark, Christopher C.; Kowalski, Adam F.; Davenport, James R. A. +17 more
We present new high-fidelity optical coronagraphic imagery of the inner ∼50 au of AU Mic’s edge-on debris disk using the BAR5 occulter of the Hubble Space Telescope Imaging Spectrograph (HST/STIS) obtained on 2018 July 26-27. This new imagery reveals that “feature A,” residing at a projected stellocentric separation of 14.2 au on the southeast sid…
An extremely X-ray weak blazar at z = 5
Ghisellini, G.; Moretti, A.; Caccianiga, A. +5 more
We present the discovery and properties of DES J014132.4-542749.9 (DES0141-54), a new powerful radio-loud active galactic nucleus (AGN) in the early Universe (z = 5.0). It was discovered by cross-matching the first data release of the Dark Energy Survey (DES DR1) with the Sidney University Molonglo Survey (SUMSS) radio catalog at 0.843 GHz. This o…
Kinetic Alfvén solitary waves in a plasma with two-temperature superthermal electron populations: the case of Saturn's magnetosphere
Singh, Manpreet; Saini, N. S.; Kourakis, I.
Thanks to the evidence provided by the Cassini spacecraft mission, it is now established that Saturn's magnetospheric plasma consists of various types of positive ions, as well as two distinct populations of electrons, at different temperatures. The electron population energy distributions are characterized by long suprathermal tails and have been…
Hubble Space Telescope Emission-line Images of Nearby 3CR Radio Galaxies: Two Photoionization, Accretion, and Feedback Modes
Sparks, William B.; Chiaberge, Marco; Capetti, Alessandro +3 more
We present HST/ACS narrowband images of a low-z sample of 19 3C radio galaxies to study the Hα and [O III] emissions from the narrow-line region. Based on nuclear emission-line ratios, we divide the sample into high- and low-excitation galaxies (HEGs and LEGs). We observe different line morphologies, extended [O III] emission, large [O III]/Hα sca…
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…