Search Publications
Deciphering Star Cluster Evolution by Shape Morphology
Hu, Qingshun; Zhang, Yu; Esamdin, Ali +2 more
We analyze the morphological evolution of open clusters and provide shape parameters for 265 open clusters. The results show that the overall shape of sample clusters becomes more elliptical as they grow older, while their core remains circular or slightly trending to circular. There is a negative correlation of the ellipticities with the number o…
S5: The Destruction of a Bright Dwarf Galaxy as Revealed by the Chemistry of the Indus Stellar Stream
Lewis, Geraint F.; Casey, Andrew R.; Erkal, Denis +14 more
The recently discovered Indus stellar stream exhibits a diverse chemical signature compared to what is found for most other streams due to the abundances of two outlier stars, Indus_0 and Indus_13. Indus_13 exhibits an extreme enhancement in rapid neutron-capture (r-)process elements with [Eu/Fe] = + 1.81. It thus provides direct evidence of the a…
Probing Jets from Young Embedded Sources: Clues from HST Near-IR [Fe II] Images
Hartigan, Patrick; Giannini, Teresa; Nisini, Brunella +6 more
We present near-infrared [Fe II] images of four Class 0/I jets (HH 1/2, HH 34, HH 111, HH 46/47) observed with the Hubble Space Telescope (HST) Wide Field Camera 3. The unprecedented angular resolution allows us to measure proper motions, jet widths and trajectories, and extinction along the jets. In all cases, we detect the counterjet, which was …
Simulating the Solar Minimum Corona in UV Wavelengths with Forward Modeling II. Doppler Dimming and Microscopic Anisotropy Effect
Susino, Roberto; Fineschi, Silvano; Cranmer, Steven R. +5 more
In ultraviolet (UV) spectropolarimetric observations of the solar corona, the existence of a magnetic field, solar wind velocity, and temperature anisotropies modify the linear polarization associated with resonant scattering. Unlike previous empirical models or global models, which present blended results of the above physical effects, in this wo…
Modeling Solar Wind Variations over an 11 Year Cycle with Alfvén Wave Dissipation: A Parameter Study
Réville, Victor; Hazra, Soumitra; Strugarek, Antoine +3 more
We study the behavior and properties of the solar wind using a 2.5D Alfvén wave (AW)-driven wind model. We first systematically compare the results of an AW-driven wind model with a polytropic approach. Polytropic magnetohydrodynamic wind models are thermally driven, while AWs act as additional acceleration and heating mechanisms in the AW-driven …
A Long Stream of Metal-poor Cool Gas around a Massive Starburst Galaxy at z = 2.67
Cooray, A.; Fu, Hai; Prochaska, J. X. +5 more
We present the first detailed dissection of the circumgalactic medium (CGM) of massive starburst galaxies at z > 2. Our target is a submillimeter galaxy (SMG) at z = 2.674 that has a star formation rate of 1200 M⊙ yr-1 and a molecular gas reservoir of 1.3 × 1011 M⊙. We characterize its CGM with two ba…
Radiative Driving of the AGN Outflows in the Narrow-line Seyfert 1 Galaxy NGC 4051
Fischer, Travis C.; Crenshaw, D. Michael; Schmitt, Henrique R. +5 more
We explore the properties of ionized gas in the nuclear and circumnuclear environment of the narrow-line Seyfert 1 galaxy NGC 4051 using spectroscopic and imaging observations from the Hubble Space Telescope (HST) and Apache Point Observatory's ARC 3.5 m Telescope. We identify an unresolved moderate-density intermediate-width component and a high-…
Detecting Biosignatures in the Atmospheres of Gas Dwarf Planets with the James Webb Space Telescope
Kendrew, Sarah; Hu, Renyu; Valenti, Jeff +5 more
Exoplanets with radii between those of Earth and Neptune have stronger surface gravity than Earth, and can retain a sizable hydrogen-dominated atmosphere. In contrast to gas giant planets, we call these planets gas dwarf planets. The James Webb Space Telescope (JWST) will offer unprecedented insight into these planets. Here, we investigate the det…
Stellar Spins in the Pleiades, Praesepe, and M35 Open Clusters
Schlaufman, Kevin C.; Healy, Brian F.; McCullough, P. R.
We analyze spectroscopic and photometric data to determine the projected inclinations of stars in three open clusters: the Pleiades, Praesepe, and M35. We determine the $\sin i$ values of 42, 35, and 67 stars in each cluster, respectively, and from their distributions we find that isotropic spins and moderate alignment are both consistent with the…
The Consistency of Chemical Clocks among Coeval Stars
Jofré, Paula; Chanamé, Julio; Casamiquela, Laia +1 more
The abundance ratios of some chemical species have been found to correlate with stellar age, leading to the possibility of using stellar atmospheric abundances as stellar age indicators. These chemical clocks have already been calibrated with solar twins and open clusters, but it remains to be seen whether they can be effective at identifying coev…