Search Publications
The Proper Motion of the Central Compact Object RX J0822-4300 in the Supernova Remnant Puppis A, Revisited
Kraft, Ralph; Becker, Werner; Winkler, P. Frank +2 more
We present an improved proper-motion measurement of the central compact object RX J0822-4300, located in the supernova remnant Puppis A. By employing a new data set taken in 2019 February by the High Resolution Camera on board the Chandra X-ray Observatory, we approximately double the available temporal baseline for our analysis to slightly more t…
Final Spitzer IRAC Observations of the Rise and Fall of SN 1987A
Gehrz, Robert D.; Woodward, Charles E.; Arendt, Richard G. +4 more
Spitzer's final Infrared Array Camera observations of SN 1987A show the 3.6 and 4.5 µm emission from the equatorial ring (ER) continues a period of steady decline. Deconvolution of the images reveals that the emission is dominated by the ring, not the ejecta, and is brightest on the west side. Decomposition of the marginally resolved emissio…
Free-form Lens Model and Mass Estimation of the High-redshift Galaxy Cluster ACT-CL J0102-4915, "El Gordo"
Sharon, K.; Zitrin, A.; Coe, D. +7 more
We examine the massive colliding cluster El Gordo, one of the most massive clusters at high redshift. We use a free-form lensing reconstruction method that avoids making assumptions about the mass distribution. We use data from the RELICS program and identify new multiply lensed system candidates. The new set of constraints and free-form method pr…
Discovery of technetium- and niobium-rich S stars: The case for bitrinsic stars
Jorissen, A.; Escorza, A.; Van Winckel, H. +4 more
Context. S stars are late-type giants with overabundances of s-process elements. They come in two flavors depending on the presence or lack of presence of technetium (Tc), an element without stable isotopes. Intrinsic S stars are Tc-rich and genuine asymptotic giant branch (AGB) stars, while extrinsic S stars owe their s-process over abundances to…
High-resolution observations of the solar photosphere, chromosphere, and transition region. A database of coordinated IRIS and SST observations
Gošić, M.; De Pontieu, B.; Sainz Dalda, A. +30 more
NASA's Interface Region Imaging Spectrograph (IRIS) provides high-resolution observations of the solar atmosphere through ultraviolet spectroscopy and imaging. Since the launch of IRIS in June 2013, we have conducted systematic observation campaigns in coordination with the Swedish 1 m Solar Telescope (SST) on La Palma. The SST provides complement…
Computational tools for the spectroscopic analysis of white dwarfs
Zakamska, Nadia L.; Chandra, Vedant; Hwang, Hsiang-Chih +1 more
The spectroscopic features of white dwarfs are formed in the thin upper layer of their stellar photosphere. These features carry information about the white dwarf's surface temperature, surface gravity, and chemical composition (hereafter 'labels'). Existing methods to determine these labels rely on complex ab-initio theoretical models, which are …
Deciphering the 3D Orion Nebula-I: Expanding Shells in the Huygens Region
Abel, N. P.; O'Dell, C. R.; Ferland, G. J.
Based on imaging and spectroscopic data, we develop a 3D model for the Huygens Region of the Orion Nebula. θ^{1} Ori C, the hottest star in the Trapezium, is surrounded by a wind-blown Central Bubble that opens SW into the Extended Orion Nebula. Outside of this feature lies a layer of ionized gas at about 0.4 pc from θ^{1} Ori C. Both of these fea…
The great Kite in the sky: A LOFAR observation of the radio source in Abell 2626
Di Gennaro, G.; Brunetti, G.; Hardcastle, M. J. +15 more
Context. The radio source at the center of the galaxy cluster Abell 2626, also known as the Kite, stands out for its unique morphology composed of four symmetric arcs. Previous studies have probed the properties of this source at different frequencies and its interplay with the surrounding thermal plasma, but the puzzle of its origin is still unso…
Super-Earth ingestion can explain the anomalously high metal abundances of M67 Y2235
Liu, Fan; Church, Ross P.; Mustill, Alexander J.
We investigate the hypothesis that ingestion of a terrestrial or super-Earth planet could cause the anomalously high metal abundances seen in a turn-off star in the open cluster M67, when compared to other turn-off stars in the same cluster. We show that the mass of the convective envelope of the star is likely only 3.45 × 10^{-3} {M_{⊙ }}, and he…
Three-dimensional structure of the Sagittarius dwarf spheroidal core from RR Lyrae
Strigari, Louis E.; Ferguson, Peter S.
We obtain distances to a sample of RR Lyrae in the central core of the Sagittarius dwarf spheroidal galaxy from OGLE data. We use these distances, along with RR Lyrae from Gaia DR2, to measure the shape of the stellar distribution within the central ∼2 kpc. The best-fitting stellar distribution is triaxial, with axis ratios 1 : 0.76 : 0.43. A prol…