Search Publications
Serendipitous discovery of a faint dwarf galaxy near a Local Volume dwarf
Karachentsev, I. D.; Makarova, L. N.; Tully, R. B. +2 more
A faint dwarf irregular galaxy has been discovered in the HST/ACS field of LV J1157+5638. The galaxy is resolved into individual stars, including the brightest magnitude of the red giant branch. The dwarf is very likely a physical satellite of LV J1157+5638. The distance modulus of LV J1157+5638 using the tip of the red giant branch (TRGB) distanc…
Stepped fans and facies-equivalent phyllosilicates in Coprates Catena, Mars
Warner, N. H.; Gupta, S.; Grindrod, P. M. +2 more
Stepped fan deposits and phyllosilicate mineralogies are relatively common features on Mars but have not previously been found in association with each other. Both of these features are widely accepted to be the result of aqueous processes, but the assumed role and nature of any water varies. In this study we have investigated two stepped fan depo…
The evolution of X-ray bursts in the `Bursting Pulsar' GRO J1744-28
Court, J. M. C.; Altamirano, D.; Albayati, A. C. +8 more
GRO J1744-28, commonly known as the `Bursting Pulsar', is a low-mass X-ray binary containing a neutron star and an evolved giant star. This system, together with the Rapid Burster (MXB 1730-33), are the only two systems that display the so-called type II X-ray bursts. These types of bursts, which last for tens of seconds, are thought to be caused …
Ionized Gas Motions and the Structure of Feedback near a Forming Globular Cluster in NGC 5253
Turner, Jean L.; Beck, Sara C.; Martin, Emily C. +2 more
We observed Brackett α 4.05 µm emission toward the supernebula in NGC 5253 with NIRSPEC on Keck II in adaptive optics mode, NIRSPAO, to probe feedback from its exciting embedded super star cluster (SSC). NIRSPEC's Slit-viewing Camera was simultaneously used to image the K-band continuum at ∼0.″1 resolution. We register the IR continuum with …
Exploring the Origins of Earth’s Nitrogen: Astronomical Observations of Nitrogen-bearing Organics in Protostellar Environments
Bergin, Edwin A.; Wampfler, S. F.; Jørgensen, Jes K. +1 more
It is not known whether the original carriers of Earth’s nitrogen were molecular ices or refractory dust. To investigate this question, we have used data and results of Herschel observations toward two protostellar sources: the high-mass hot core of Orion KL, and the low-mass protostar IRAS 16293-2422. Toward Orion KL, our analysis of the molecula…
Inorbit performance of the Hard X-ray Telescope (HXT) on board the Hitomi (ASTRO-H) satellite
Maeda, Yoshitomo; Ishida, Manabu; Kunieda, Hideyo +16 more
Hitomi (ASTRO-H) carries two Hard X-ray Telescopes (HXTs), which can focus x-rays up to 80 keV. Combined with the hard x-ray imagers (HXIs) that detect the focused x-rays, imaging spectroscopy in the high-energy band from 5 to 80 keV is made possible. We studied characteristics of HXTs after the launch, such as the encircled energy function (EEF) …
Circumgalactic Gas at Its Extreme: Tidal Gas Streams around the Whale Galaxy NGC 4631 Explored with HST/COS
Wakker, B. P.; Gentile, G.; Winkel, B. +8 more
We present a detailed analysis of the absorption properties of one of the tidal gas streams around the “Whale” galaxy NGC 4631 in the direction of the quasar 2MASS J12421031+3214268. Our study is based on ultraviolet spectral data obtained with the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope (HST) and 21cm-data from the H…
Statistical Study of Magnetic Topology for Eruptive and Confined Solar Flares
Xu, Yan; Wang, Haimin; Liu, Siqing +1 more
Large flares and halo coronal mass ejections (CMEs) can often cause strong space environment disturbances and sequently a series of space environment effects. The X-class flares associated with halo CMEs are particular prone to these effects. In this paper, 58 X-class flares were collected and studied with the source locations in 30° from the disk…
The Main Belt Asteroid Shape Distribution from Gaia Data Release 2
Moskovitz, Nicholas; Mommert, Michael; Trilling, David E. +2 more
Gaia Data Release 2 includes observational data for 14099 pre-selected asteroids. From the sparsely sampled G-band photometry, we derive lower-limit light curve amplitudes for 11665 main belt asteroids (MBA) in order to provide constraints on the distribution of shapes in the asteroid main belt. Assuming a triaxial shape model for each asteroid, d…
Does Nearby Open Flux Affect the Eruptivity of Solar Active Regions?
DeRosa, Marc L.; Barnes, Graham
The most energetic solar flares are typically associated with the ejection of a cloud of coronal material into the heliosphere in the form of a coronal mass ejection (CME). However, large flares exist that are not accompanied by a CME. The existence of these noneruptive flares raises the question of whether such flares suffer from a lack of access…