Search Publications
HST PanCET Program: A Complete Near-UV to Infrared Transmission Spectrum for the Hot Jupiter WASP-79b
Nikolov, Nikolay; Sing, David K.; MacDonald, Ryan J. +12 more
We present a new optical transmission spectrum of the hot Jupiter WASP-79b. We observed three transits with the STIS instrument mounted on the Hubble Space Telescope (HST), spanning 0.3-1.0 µm. Combining these transits with previous observations, we construct a complete 0.3-5.0 µm transmission spectrum of WASP-79b. Both HST and ground-…
TOI 540 b: A Planet Smaller than Earth Orbiting a Nearby Rapidly Rotating Low-mass Star
Latham, David W.; Ziegler, Carl; Vanderspek, Roland +20 more
We present the discovery of TOI 540 b, a hot planet slightly smaller than Earth orbiting the low-mass star 2MASS J05051443-4756154. The planet has an orbital period of P = 1.239149 days (±170 ms) and a radius of $r=0.903\pm 0.052{R}_{\oplus }$ , and is likely terrestrial based on the observed mass-radius distribution of small exoplanets at similar…
A Lyα Transit Left Undetected: the Environment and Atmospheric Behavior of K2-25b
Youngblood, Allison; Mann, Andrew W.; Charbonneau, David +6 more
K2-25b is a Neptune-sized exoplanet (3.45R⊕) that orbits its M4.5 host with a period of 3.48 days. Due to its membership in the Hyades Cluster, the system has a known age (727 ± 75 Myr). K2-25b's youth and its similarities with Gl 436b suggested that K2-25b could be undergoing strong atmospheric escape. We observed two transits of K2-25…
Concordance: In-flight Calibration of X-Ray Telescopes without Absolute References
Drake, Jeremy J.; Guainazzi, Matteo; van Dyk, David A. +7 more
We describe a process for cross-calibrating the effective areas of X-ray telescopes that observe common targets. The targets are not assumed to be "standard candles" in the classic sense, in that we assume that the source fluxes have well-defined, but a priori unknown values. Using a technique developed by Chen et al. that involves a statistical m…
Quest for the Upcoming Periastron Passage of an Episodic Dust Maker and Particle-accelerating Colliding-wind Binary: WR 125
Pandey, J. C.; Pandey, S. B.; Sharma, Saurabh +4 more
We have carried out a long-term infrared and X-ray investigation of the colliding-wind binary WR 125 (WC7 + O9III). The source was monitored using AstroSat Soft X-ray Telescope and the Tata Institute of Fundamental Research Near Infrared Imaging Camera-II mounted at the back of 3.6 m Devasthal Optical Telescope. WR 125 appeared brighter in the nea…
What's Behind the Elephant's Trunk? Identifying Young Stellar Objects on the Outskirts of IC 1396
Principe, David A.; Wolk, Scott J.; Kim, Jinyoung Serena +2 more
Empirically, the estimated lifetime of a typical protoplanetary disk is <5-10 Myr. However, the disk lifetimes required to produce a variety of observed exoplanetary systems may exceed this timescale. Some hypothesize that this inconsistency is due to estimating disk fractions at the cores of clusters, where radiation fields external to a star-…
Five New Hot Jupiter Transits Investigated with Swift-UVOT
Rauscher, Emily; King, George W.; Reynolds, Mark +3 more
Short-wavelength exoplanet transit measurements have been used to probe mass loss in exoplanet atmospheres. We present the Swift-UVOT transit light curves for five hot Jupiters orbiting UV-bright F-type stars: XO-3, KELT-3, WASP-3, WASP-62, and HAT-P-6. We report one positive transit detection of XO-3b and one marginal detection of KELT-3b. We pla…
HD 63021: Chromospheric Activity and Mass Transfer in a Close Binary
Lester, Kathryn V.; Labadie-Bartz, Jonathan; Stringfellow, Guy S. +13 more
Prompted by X-ray detections from multiple surveys, we investigated the A-type star HD 63021 and found that it is a double-lined spectroscopic binary with highly variable emission associated with the primary star. Analysis of our multiepoch spectroscopic observations, the majority of which were carried out on small-aperture telescopes, indicates a…
Change-point Detection and Image Segmentation for Time Series of Astrophysical Images
Zezas, Andreas; Xu, Cong; Kashyap, Vinay L. +2 more
Many astrophysical phenomena are time-varying, in the sense that their intensity, energy spectrum, and/or the spatial distribution of the emission suddenly change. This paper develops a method for modeling a time series of images. Under the assumption that the arrival times of the photons follow a Poisson process, the data are binned into 4D grids…
X-Rays in Cepheids: XMM-Newton Observations of η Aql
Mérand, Antoine; Drake, Jeremy J.; Guzik, Joyce A. +13 more
X-ray bursts have recently been discovered in the Cepheids δ Cep and β Dor modulated by the pulsation cycle. We have obtained an observation of the Cepheid η Aql with the XMM-Newton satellite at the phase of maximum radius; the phase at which there is a burst of X-rays in δ Cep. No X-rays were seen from the Cepheid η Aql at this phase, and the imp…