Search Publications
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 …
Mapping the Milky Way in 5D with 170 Million Stars
Conroy, Charlie; Ting, Yuan-Sen; Cargile, Phillip A. +18 more
We present Augustus, a catalog of distance, extinction, and stellar parameter estimates for 170 million stars from 14 mag < r < 20 mag and with ∣b∣ > 10° drawing on a combination of optical to near-infrared photometry from Pan-STARRS, 2MASS, UKIDSS, and unWISE along with parallax measurements from Gaia DR2 and 3D dust extinction maps. Aft…
BP3M: Bayesian Positions, Parallaxes, and Proper Motions Derived from the Hubble Space Telescope and Gaia Data
van der Marel, Roeland P.; Watkins, Laura L.; Libralato, Mattia +9 more
We present a hierarchical Bayesian pipeline, BP3M, that measures positions, parallaxes, and proper motions (PMs) for cross-matched sources between Hubble Space Telescope (HST) images and Gaia—even for sparse fields (N * < 10 per image)—expanding from the recent GaiaHub tool. This technique uses Gaia-measured astrometry as priors to p…
An Elemental Abundance Diagnostic for Coordinated Solar Orbiter/SPICE and Hinode/EIS Observations
Matthews, Sarah A.; Warren, Harry P.; Brooks, David H. +2 more
Plasma composition measurements are a vital tool for the success of current and future solar missions, but density- and temperature-insensitive spectroscopic diagnostic ratios are sparse, and their underlying accuracy in determining the magnitude of the first ionization potential (FIP) effect in the solar atmosphere remains an open question. Here …
A 9 Month Hubble Space Telescope Near-UV Survey of M87. II. A Strongly Enhanced Nova Rate near the Jet of M87
Shara, Michael M.; Sparks, William; Lessing, Alec M. +3 more
The 135 classical novae that we have discovered in M87 with two Hubble Space Telescope imaging surveys appear to be strongly concentrated along that galaxy's jet. Detailed simulations show that the likelihood that this distribution occurred by chance is of order 0.3%. The novae near the jet display outburst characteristics (peak luminosities, colo…