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A New Candidate Transitional Millisecond Pulsar in the Subluminous Disk State: 4FGL J0407.7-5702
Strader, Jay; Dage, Kristen C.; Chomiuk, Laura +7 more
We report the discovery of a variable optical and X-ray source within the error ellipse of the previously unassociated Fermi Large Area Telescope γ-ray source 4FGL J0407.7-5702. A 22 ks observation from XMM-Newton/European Photon Imaging Camera (EPIC) shows an X-ray light curve with rapid variability and flaring. The X-ray spectrum is well fit by …
Rotational spectral modulation of cloudless atmospheres for L/T brown dwarfs and extrasolar giant planets
Apai, D.; Tremblin, P.; Bonnefoy, M. +5 more
Aims: The rotational spectral modulation (spectro-photometric variability) of brown dwarfs is usually interpreted as a sign indicating the presence of inhomogeneous cloud covers in the atmosphere. This paper is aimed at exploring the role of temperature fluctuations in these spectral modulations. These fluctuations could naturally arise in a …
A Mini-Neptune and a Radius Valley Planet Orbiting the Nearby M2 Dwarf TOI-1266 in Its Venus Zone: Validation with the Habitable-zone Planet Finder
Cochran, William D.; Endl, Michael; Mahadevan, Suvrath +26 more
We report on the validation of two planets orbiting the nearby (36 pc) M2 dwarf TOI-1266 observed by the TESS mission. This system is one of a few M dwarf multiplanet systems with close-in planets where the inner planet is substantially larger than the outer planet. The inner planet is sub-Neptune-sized (R = 2.46 ± 0.08 R⊕) with an orbi…
Burst-induced coronal cooling in GS 1826-24. The clock wagging its tail
Sánchez-Fernández, C.; Kuulkers, E.; Poutanen, J. +2 more
Type I X-ray bursts in GS 1826-24, and in several other systems, may induce cooling of the hot inner accretion flow that surrounds the bursting neutron star. Given that GS 1826-24 remained persistently in the hard state over the period 2003-2008 and presented regular bursting properties, we stacked the spectra of the X-ray bursts detected by INTEG…
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 …