Search Publications
Lava heating and loading of ice sheets on early Mars: Predictions for meltwater generation, groundwater recharge, and resulting landforms
Head, James W.; Cassanelli, James P.
Recent modeling studies of the early Mars climate predict a predominantly cold climate, characterized by the formation of regional ice sheets across the highland areas of Mars. Formation of the predicted "icy highlands" ice sheets is coincident with a peak in the volcanic flux of Mars involving the emplacement of the Late Noachian - Early Hesperia…
Luminosity-dependent change of the emission diagram in the X-ray pulsar 4U 1626-67
Gilfanov, Marat; Koliopanos, Filippos
We detect variability of the Fe K α emission line in the spectrum of X-ray pulsar 4U 1626-67, correlated with changes in its luminosity and in the shape of its pulse profile. Analysis of archival Chandra and RXTE observations revealed the presence of an intrinsically narrow Fe K α emission line in the spectrum obtained during the source's current …
Quantitative prediction of type II solar radio emission from the Sun to 1 AU
Cairns, Iver H.; Schmidt, J. M.
Coronal mass ejections (CMEs) are frequently associated with shocks and type II solar radio bursts. Despite involving fundamental plasma physics and being the archetype for collective radio emission from shocks, type II bursts have resisted detailed explanation for over 60 years. Between 29 November and 1 December 2013 the two widely separated spa…
Strong Lyα Emission in the Proximate Damped Lyα Absorption Trough toward the Quasar SDSS J095253.83+011422.0
Shu, Xinwen; Gu, Qiusheng; Li, Zhenzhen +10 more
SDSS J095253.83+011422.0 (J0952+0114) was reported by Hall et al. as an exotic quasar at zem = 3.020. In contrast to prominent broad metal-line emission with FWHM ∼ 9000 km s-1, only a narrow Lyα emission line is present with FWHM ∼ 1000 km s-1. The absence of a broad Lyα emission line has been a mystery for more t…
New Insights into the Spectral Variability and Physical Conditions of the X-Ray Absorbers in NGC 4151
Turner, T. J.; Kraemer, S. B.; Crenshaw, D. M. +1 more
We investigate the relationship between the long-term X-ray spectral variability in the Seyfert 1.5 galaxy NGC 4151 and its intrinsic absorption, by comparing the 2014 simultaneous ultraviolet/X-ray observations taken with Hubble STIS Echelle and Chandra HETGS with archival observations from Chandra, XMM-Newton, and Suzaku. The observations are di…
Morphological Properties of Lyα Emitters at Redshift 4.86 in the Cosmos Field: Clumpy Star Formation or Merger?
Koekemoer, Anton M.; Kajisawa, Masaru; Nagao, Tohru +7 more
We investigate morphological properties of 61 Lyα emitters (LAEs) at z = 4.86 identified in the COSMOS field, based on Hubble Space Telescope Advanced Camera for Surveys (ACS) imaging data in the F814W band. Out of the 61 LAEs, we find the ACS counterparts for 54 LAEs. Eight LAEs show double-component structures with a mean projected separation of…
Hektor - an exceptional D-type family among Jovian Trojans
Nesvorný, D.; Brož, M.; Durda, D. D. +4 more
In this work, we analyse Jovian Trojans in the space of suitable resonant elements and we identify clusters of possible collisional origin by two independent methods: the hierarchical clustering and a so-called randombox. Compared to our previous work, we study a twice larger sample. Apart from Eurybates, Ennomos and 1996 RJ families, we have foun…
Baryon content and dynamic state of galaxy clusters: XMM-Newton observations of A1095 and A1926
Tripp, Todd M.; Wang, Q. Daniel; Li, Zhiyuan +3 more
We have initiated a program to study the baryon content and dynamic state of galaxy clusters. Here we present results primarily from XMM-Newton observations of two optically selected galaxy clusters, A1095 (z ≃ 0.210) and A1926 (z ≃ 0.136). We find that both of them are actually cluster pairs at similar redshifts. We characterize the temperatures …
An AO-assisted Variability Study of Four Globular Clusters
Contreras Ramos, R.; Catelan, M.; Hakala, P. +4 more
The image-subtraction technique applied to study variable stars in globular clusters represented a leap in the number of new detections, with the drawback that many of these new light curves could not be transformed to magnitudes due to severe crowding. In this paper, we present observations of four Galactic globular clusters, M 2 (NGC 7089), M 10…
The Quest for the Largest Depleted Galaxy Core: Supermassive Black Hole Binaries and Stalled Infalling Satellites
Graham, Alister W.; Bonfini, Paolo
Partially depleted cores are practically ubiquitous in luminous early-type galaxies (M B ≲ -20.5 mag) and are typically smaller than 1 kpc. In one popular scenario, supermassive black hole (SMBH) binaries—established during dry (I.e., gas-poor) galaxy mergers—kick out the stars from a galaxy’s central region via three-body interaction…