Search Publications
Gaia GraL: Gaia DR2 Gravitational Lens Systems. VI. Spectroscopic Confirmation and Modeling of Quadruply Imaged Lensed Quasars
Djorgovski, S. G.; Stern, D.; Surdej, J. +23 more
Combining the exquisite angular resolution of Gaia with optical light curves and WISE photometry, the Gaia Gravitational Lenses group (GraL) uses machine-learning techniques to identify candidate strongly lensed quasars, and has confirmed over two dozen new strongly lensed quasars from the Gaia Data Release 2. This paper reports on the 12 quadrupl…
HST/WFC3 Grism Observations of z 1 Clusters: Evidence for Rapid Outside-in Environmental Quenching from Spatially Resolved Hα Maps
Matharu, Jasleen; Muzzin, Adam; van der Wel, Arjen +12 more
We present and publicly release (www.gclasshst.com) the first spatially resolved Hα maps of star-forming cluster galaxies at z ~ 1, made possible with the Wide Field Camera 3 (WFC3) G141 grism on the Hubble Space Telescope (HST). Using a similar but updated method to 3D-HST in the field environment, we stack the Hα maps in bins of stellar mass, me…
Long-term Spectroscopic Survey of the Pleiades Cluster: The Binary Population
Torres, Guillermo; Latham, David W.; Quinn, Samuel N.
We present the results of a spectroscopic monitoring program of the Pleiades region aimed at completing the census of spectroscopic binaries in the cluster, extending it to longer periods than previously reachable. We gathered 6104 spectra of 377 stars between 1981 and 2021, and merged our radial velocities with 1151 measurements from an independe…
The TW Hya Rosetta Stone Project. II. Spatially Resolved Emission of Formaldehyde Hints at Low-temperature Gas-phase Formation
Wilner, David J.; Cleeves, L. Ilsedore; Walsh, Catherine +15 more
Formaldehyde (H2CO) is an important precursor to organics like methanol (CH3OH). It is important to understand the conditions that produce H2CO and prebiotic molecules during star and planet formation. H2CO possesses both gas-phase and solid-state formation pathways, involving either UV-produced radical …
Are Massive Dense Clumps Truly Subvirial? A New Analysis Using Gould Belt Ammonia Data
Caselli, Paola; Di Francesco, James; Rosolowsky, Erik +22 more
Dynamical studies of dense structures within molecular clouds often conclude that the most massive clumps contain too little kinetic energy for virial equilibrium, unless they are magnetized to an unexpected degree. This raises questions about how such a state might arise, and how it might persist long enough to represent the population of massive…
On a Possible Solution to the Tidal Realignment Problem for Hot Jupiters
Winn, Joshua N.; Penev, Kaloyan; Anderson, Kassandra R.
Hot stars with hot Jupiters have a wide range of obliquities, while cool stars with hot Jupiters tend to have low obliquities. An enticing explanation for this pattern is tidal realignment of the cool host stars, although this explanation assumes that obliquity damping occurs faster than orbital decay, an assumption that needs further exploration.…
Detection of a Multiphase Ultrafast Wind in the Narrow-line Seyfert 1 Galaxy Mrk 1044
Santos-Lleó, M.; Peterson, B. M.; Nicastro, F. +6 more
We present a detailed analysis of XMM-Newton X-ray spectra of the Narrow-Line Seyfert 1 galaxy Mrk 1044. We find robust evidence for a multiphase, ultrafast outflow, traced by four separate components in the grating spectrum. One component has high column density and ionization state, and is outflowing at ~0.15c. The other three wind components ha…
Solar Anti-Hale Bipolar Magnetic Regions: A Distinct Population with Systematic Properties
Muñoz-Jaramillo, Andrés; Campusano, Luis E.; Navarrete, Benjamín
Besides their causal connection with long and short-term magnetic variability, solar bipolar magnetic regions are our chief source of insight into the location, size, and properties of large-scale toroidal magnetic structures in the solar interior. The great majority of these regions (≈95%) follow a systematic east-west polarity orientation (Hale'…
X-Ray Constraint on the Location of the AGN Torus in the Circinus Galaxy
Tanimoto, Atsushi; Ueda, Yoshihiro; Kawamuro, Taiki +5 more
The location of the obscuring "torus" in an active galactic nucleus (AGN) is still an unresolved issue. The line widths of X-ray fluorescence lines originating from the torus, particularly Fe Kα, carry key information on the radii of line-emitting regions. Utilizing XCLUMPY, an X-ray clumpy torus model, we develop a realistic model of emission lin…
A New Identity Card for the Bulge Globular Cluster NGC 6440 from Resolved Star Counts
Vesperini, Enrico; Pallanca, Cristina; Dalessandro, Emanuele +6 more
We present a new identity card for the cluster NGC 6440 in the Galactic Bulge. We have used a combination of high-resolution Hubble Space Telescope images, wide-field ground-based observations performed with the ESO-FORS2, and the public survey catalog Pan-STARRS to determine the gravitational center, projected density profile, and structural para…