Search Publications
Probing the Nature of Rotation in the Pleiades, Alpha Persei, and Hyades Clusters
Hao, C. J.; Xu, Y.; Hou, L. G. +5 more
Unraveling the internal kinematics of open clusters is crucial for understanding their formation and evolution. However, there is a dearth of research on this topic, primarily due to the lack of high-quality kinematic data. Using the exquisite-precision astrometric parameters and radial velocities provided by Gaia data release 3, we investigate th…
Discovery of a Proto–White Dwarf with a Massive Unseen Companion
Hermes, J. J.; Zakamska, Nadia L.; El-Badry, Kareem +8 more
We report the discovery of SDSS J022932.28+713002.7, a nascent extremely low-mass (ELM) white dwarf (WD) orbiting a massive (>1 M ⊙ at 2σ confidence) companion with a period of 36 hr. We use a combination of spectroscopy, including data from the ongoing fifth-generation Sloan Digital Sky Survey (SDSS-V), and photometry to measure the…
The Clearing Timescale for Infrared-selected Star Clusters in M83 with HST
Calzetti, Daniela; Johnson, Kelsey E.; Sabbi, Elena +6 more
We present an analysis of Hubble Space Telescope data from Wide Field Camera 3 (WFC3)/Ultraviolet Imaging Spectrometer, WFC3/IR, and the Advanced Camera for Surveys, investigating the young stellar cluster (YSC) population in the face-on spiral galaxy M83. Within the field of view of the IR pointings, we identify 454 sources with compact F814W con…
Relative Yield of Thermal and Nonthermal Emission during Weak Flares Observed by STIX during 2021 September 20–25
Awasthi, Arun Kumar; Mrozek, Tomasz; Kołomański, Sylwester +3 more
The disparate nature of the thermal–nonthermal energy partition during flares, particularly during weak flares, is still an open issue. Following the Neupert effect, quantifying the relative yield of X-ray emission in different energy bands can enable the inferring of the underlying energy release mechanism. During 2021 September 20–25, the Solar …
The Proper Motion of the High Galactic Latitude Pulsar Calvera
Mereghetti, S.; Gotthelf, E. V.; Halpern, J. P. +2 more
Calvera (1RXS J141256.0+792204) is a pulsar of characteristic age 285 kyr at a high Galactic latitude of b = +37°, detected only in soft thermal X-rays. We measure a new and precise proper motion for Calvera using Chandra High Resolution Camera observations obtained 10 yr apart. We also derive a new phase-connected ephemeris using 6 yr of NICER da…
Why Observations at Mid-infrared Wavelengths Partially Mitigate M Dwarf Star Host Stellar Activity Contamination in Exoplanet Transmission Spectroscopy
Seager, Sara; Shapiro, Alexander I.
Exoplanet atmosphere transmission spectroscopy for planets orbiting M dwarf stars faces significant challenges due to contamination from stellar magnetic features, i.e., spots and faculae. These features make the stellar surface inhomogeneous and introduce wavelength-dependent signals in the transmission spectrum that complicate its analysis. We i…
Origins of Very Low Helium Abundance Streams Detected in the Solar Wind Plasma
Yashiro, Seiji; Gopalswamy, N.; Srivastava, Nandita +4 more
The abundance of helium (A He) in the solar wind exhibits variations typically in the range from 2% to 5% with respect to solar cycle activity and solar wind velocity. However, there are instances where the observed A He is exceptionally low (<1%). These low-A He occurrences are detected both near the Sun and at…
METAL-Z: Measuring Dust Depletion in Low-metallicity Dwarf Galaxies
Jenkins, Edward B.; Gordon, Karl D.; Rafelski, Marc +6 more
The cycling of metals between interstellar gas and dust is a critical aspect of the baryon cycle of galaxies, yet our understanding of this process is limited. This study focuses on understanding dust depletion effects in the low-metallicity regime (<20% Z ⊙) typical of cosmic noon. Using medium-resolution UV spectroscopy from the Co…
Spectral Modeling of the Supersoft X-Ray Source CAL87 Based on Radiative Transfer Codes
Tsujimoto, Masahiro; Wada, Qazuya; Ebisawa, Ken +2 more
Supersoft X-ray sources (SSSs) are white dwarf (WD) binaries that radiate almost entirely below ~1 keV. Their X-ray spectra are often complex when viewed with the X-ray grating spectrometers, where numerous emission and absorption features are intermingled and hard to separate. The absorption features are mostly from the WD atmosphere, for which r…
Jovian Electrons in the Inner Heliosphere: Opportunities for Multi-spacecraft Observations and Modeling
Mitchell, J. G.; Rankin, J. S.; Ferreira, S. E. S. +11 more
In this paper we explore the idea of using multi-spacecraft observations of Jovian electrons to measure the 3D distribution of these particles in the inner heliosphere. We present simulations of Jovian electron intensities along selected spacecraft trajectories for 2021 and compare these, admittedly qualitatively, to these measurements. Using the …