Search Publications
A Highly Magnified Gravitationally Lensed Red QSO at z = 2.5 with a Significant Flux Ratio Anomaly
Djorgovski, S. G.; Stern, Daniel; Lacy, Mark +12 more
We present the discovery of a gravitationally lensed dust-reddened QSO at z = 2.517, identified in a survey for QSOs by infrared selection. Hubble Space Telescope imaging reveals a quadruply lensed system in a cusp configuration, with a maximum image separation of ~1.″8. We find that, compared to the central image of the cusp, the neighboring brig…
Hubble WFC3 Spectroscopy of the Terrestrial Planets L 98-59 c and d: No Evidence for a Clear Hydrogen Dominated Primary Atmosphere
Zhu, Yi-Nan; Zhou, Li; Ma, Bo +1 more
The nearby bright M-dwarf star L 98-59 has three terrestrial-sized planets. One challenge remaining in characterizing atmospheres around such planets is that it is not known a priori whether they possess any atmospheres. Here we report on study of the atmospheres of L 98-59 c and L 98-59 d using near-infrared spectral data from the G141 grism of H…
Detection of He++ ion in the star-forming ring of the Cartwheel using MUSE data and ionizing mechanisms
Charlot, S.; Bruzual, G.; Plat, A. +3 more
We here report the detection of the nebular He II λ4686 line in 32 H II regions in the metal-poor collisional ring galaxy Cartwheel using the Multi-Unit Spectroscopic Explorer (MUSE) data set. The measured I(He II λ4686)/I(H β) ratio varies from 0.004 to 0.07, with a mean value of 0.010 ± 0.003. Ten of these 32 H II regions are coincident with the…
Estimating Distances from Parallaxes. VI. A Method for Inferring Distances and Transverse Velocities from Parallaxes and Proper Motions Demonstrated on Gaia Data Release 3
Bailer-Jones, C. A. L.
The accuracy of stellar distances inferred purely from parallaxes degrades rapidly with distance. Proper motion measurements, when combined with some idea of typical velocities, provide independent information on stellar distances. Here, I build a direction- and distance-dependent model of the distribution of stellar velocities in the Galaxy, then…
Temperature of quiet Sun small scale brightenings observed by EUI on board Solar Orbiter: Evidence for a cooler component
Mierla, M.; Zhukov, A. N.; Berghmans, D. +16 more
Context. On May 30, 2020, small and short-lived extreme-UV (EUV) brightenings in the quiet Sun were observed over a four-minute sequence by the EUV channel of the Extreme Ultraviolet Imager - High Resolution Imager (EUIHRIEUV) on board the Solar Orbiter. The brightenings' physical origin and possible impact on coronal or transition regi…
Carbon stars as standard candles - III. Un-binned maximum likelihood fitting and comparison with TRGB estimations
Rousseau-Nepton, Laurie; Heyl, Jeremy; Richer, Harvey +2 more
In the second paper of this series, we developed a new distance determination method using the median J magnitude of carbon-rich asymptotic giant branch stars (CS) as standard candles and the Magellanic Clouds as the fundamental calibrators. The J-band CS luminosity function was modelled using a modified Lorentzian distribution whose parameters we…
High-mass eclipsing binaries: A testbed for models of interior structure and evolution. Accurate fundamental properties and surface chemical composition for V1034 Sco, GL Car, V573 Car, and V346 Cen
Southworth, J.; Tkachenko, A.; Van Reeth, T. +2 more
Aims: The surface chemical compositions of stars are affected by physical processes that bring the products of thermonuclear burning to the surface. Despite their potential in helping us understand the structure and evolution of stars, elemental abundances are available for only a few high-mass binary stars. We aim to enlarge this sample by d…
What boost galaxy mergers in two massive galaxy protoclusters at z = 2.24?
Fan, Xiaohui; Cai, Zheng; Zheng, Xian Zhong +10 more
Characterizing the structural properties of galaxies in high-redshift protoclusters is key to our understanding of the environmental effects on galaxy evolution in the early stages of galaxy and structure formation. In this study, we assess the structural properties of 85 and 87 Hα emission-line candidates (HAEs) in the densest regions of two mass…
Evidence of a Massive Stellar Disruption in the X-Ray Spectrum of ASASSN-14li
Ramirez-Ruiz, Enrico; Drake, Jeremy J.; Raymond, John +7 more
The proximity and duration of the tidal disruption event ASASSN-14li led to the discovery of narrow, blueshifted absorption lines in X-rays and UV. The gas seen in X-ray absorption is consistent with bound material close to the apocenter of elliptical orbital paths, or with a disk wind similar to those seen in Seyfert-1 active galactic nuclei. We …
SRGeJ045359.9+622444: A 55 Minute Period Eclipsing AM Canum Venaticorum Star Discovered from a Joint SRG/eROSITA + ZTF Search
Szkody, Paula; El-Badry, Kareem; Graham, Matthew J. +24 more
AM Canum Venaticorum (AM CVn) systems are ultracompact binaries where a white dwarf accretes from a helium-rich degenerate or semidegenerate donor. Some AM CVn systems will be among the loudest sources of gravitational waves for the upcoming Laser Interferometer Space Antenna; yet the formation channel of AM CVns remains uncertain. We report the s…