Search Publications
The Positron Puzzle
Siegert, Thomas
The Positron Puzzle is a half-century old conundrum about the origin of the Galactic
Mineralogy, Morphology, and Emplacement History of the Maaz Formation on the Jezero Crater Floor From Orbital and Rover Observations
Liu, Yang; Horgan, Briony; Ravanis, Eleni +42 more
The first samples collected by the Perseverance rover on the Mars 2020 mission were from the Maaz formation, a lava plain that covers most of the floor of Jezero crater. Laboratory analysis of these samples back on Earth would provide important constraints on the petrologic history, aqueous processes, and timing of key events in Jezero crater. How…
Search for lithium-rich giants in 32 open clusters with high-resolution spectroscopy★
Pancino, E.; Bossini, D.; Sousa, S. G. +3 more
Context. Lithium-rich giant stars are rare and their existence poses a challenge to our understanding of stellar structure and evolution. In particular, open clusters aptly constrain the mass and age of their members, offering a unique opportunity to understand the evolutionary stage where Li enrichment occurs.
Aims: We take advantage of the …
Testing external photoevaporation in the σ-Orionis cluster with spectroscopy and disk mass measurements
Lodato, G.; Williams, J. P.; Ansdell, M. +8 more
Context. The evolution of protoplanetary disks is regulated by an interplay of several processes, either internal to the system or related to the environment. As most of the stars and planets, including our own Solar System, have formed in massive stellar clusters that contain OB-type stars, studying the effects of UV radiation on disk evolution i…
The Q Branch Cooling Anomaly Can Be Explained by Mergers of White Dwarfs and Subgiant Stars
Blouin, Simon; Shen, Ken J.; Breivik, Katelyn
Gaia's exquisite parallax measurements allowed for the discovery and characterization of the Q branch in the Hertzsprung-Russell diagram, where massive C/O white dwarfs (WDs) pause their dimming due to energy released during crystallization. Interestingly, the fraction of old stars on the Q branch is significantly higher than in the population of …
Redder than Red: Discovery of an Exceptionally Red L/T Transition Dwarf
Meisner, Aaron M.; Cushing, Michael C.; Kirkpatrick, J. Davy +24 more
We present the discovery of CWISE J050626.96+073842.4 (CWISE J0506+0738), an L/T transition dwarf with extremely red near-infrared colors discovered through the Backyard Worlds: Planet 9 citizen science project. Photometry from UKIRT and CatWISE give a (J - K)MKO color of 2.97 ± 0.03 mag and a J MKO - W2 color of 4.93 ± 0.02 …
Planetesimals at DZ stars - I. Chondritic compositions and a massive accretion event
Dufour, Patrick; Desch, Steven J.; Melis, Carl +4 more
There is a wealth of evidence to suggest that planetary systems can survive beyond the main sequence. Most commonly, white dwarfs are found to be accreting material from tidally disrupted asteroids, whose bulk compositions are reflected by the metals polluting the stellar photospheres. While many examples are known, most lack the deep, high-resolu…
Identifying the SN 2022acko progenitor with JWST
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Sand, David J. +17 more
We report on analysis using the JWST to identify a candidate progenitor star of the Type II-plateau (II-P) supernova SN 2022acko in the nearby, barred spiral galaxy NGC 1300. To our knowledge, our discovery represents the first time JWST has been used to localize a progenitor system in pre-explosion archival Hubble Space Telescope (HST) images. We…
Evidence for a radiation belt around a brown dwarf
Pérez-Torres, M.; Guirado, J. C.; Marcaide, J. M. +2 more
Ultracool dwarfs (UCDs) are a category of astronomical objects that includes brown dwarfs and very-low-mass stars. Radio observations of UCDs have measured their brightness as a function of time (light curves) and spectral energy distributions, providing insight into their magnetic fields. We present spatially resolved radio observations of the br…
Extreme broad He II emission at high and low redshifts: the dominant role of VMS in NGC 3125-A1 and CDFS131717
Hayes, Matthew; Smith, Linda J.; Charlot, Stephane +6 more
Super star cluster (SSC) A1 ($3.1\times 10^5\, \mathrm{M}_\odot$) in NGC 3125 has one of the strongest ($EW=4.6\pm 0.5\,$ Å) broad ($FWHM=1131\pm 40\,$ km s-1) He II λ1640 emission lines in the nearby universe and constitutes an important template for interpreting observations of extreme He II emitters out to redshifts of z ~ 2 - 3. We …