Search Publications
Hubble Space Telescope FUV observations of M31's globular clusters suggest a spatially homogeneous helium-enriched subpopulation
Kundu, Arunav; Strader, Jay; Zepf, Stephen E. +4 more
We present high spatial resolution, far ultraviolet (FUV) F140LP observations of 12 massive globular clusters in M 31 obtained using the ACS/SBC on the Hubble Space Telescope (HST). These observations resolve the cluster profiles to scales similar to their core radii and enable the study of the spatial distribution of blue and extreme horizontal b…
X-Ray Study of Variable Gamma-Ray Pulsar PSR J2021+4026
Takata, J.; Zhao, J.; Lin, L. C. C. +2 more
PSR J2021+4026 showed a sudden decrease in the gamma-ray emission at the glitch that occurred around 2011 October 16, and a relaxation of the flux to the pre-glitch state at around 2014 December. We report X-ray analysis results of the data observed by XMM-Newton on 2015 December 20 in the post-relaxation state. To examine any change in the X-ray …
On the Asymmetry Between Upward and Downward Field-Aligned Currents Interacting With the Ionosphere
Streltsov, A. V.
The paper presents results from the numerical study of the magnetosphere-ionosphere interactions driven by the large-scale electric field in the magnetically conjugate, high-latitude regions of northern and southern hemispheres. Simulations of the two-fluid MHD model demonstrate that these interactions can lead to a generation of a system of small…
Cracking the Conundrum of F-supergiant Coronae
Ayres, Thomas R.
Chandra X-ray and HST far-ultraviolet (FUV) observations of three early-F supergiants have shed new light on a previous puzzle involving a prominent member of the class: α Persei (HD 20902: F5 Ib). The warm supergiant is a moderately strong, hard coronal (T∼ {10}7 K) X-ray source, but has 10 times weaker “subcoronal” Si IV 1393 Å (T∼ 8×…
Understanding the origin of methane on Mars through isotopic and molecular data from the ExoMars orbiter
Etiope, Giuseppe
The identification of methane (CH4) and its origin on Mars is a major mandate of the ExoMars mission, because this gas has potential links with biological activity. Starting in 2018, the NOMAD spectrometer suite of the ExoMars Trace Gas Orbiter can measure, in the martian atmosphere, important parameters that can contribute to identific…
X-ray cavities in the hot corona of the lenticular galaxy NGC 4477
Li, Yijia; Jones, Christine; Su, Yuanyuan
NGC 4477 is a low-mass lenticular galaxy in the Virgo Cluster, residing at 100 kpc to the north of M87. Using a total of 116 ks Chandra observations, we study the interplay between its hot (∼0.3 keV) gas halo and the central supermassive black hole. A possible cool core is indicated by the short cooling time of the gas at the galaxy centre. We ide…
Dense Molecular Filaments Feeding a Starburst: ALMA Maps of CO(3-2) in Henize 2-10
Turner, Jean L.; Beck, Sara C.; Consiglio, S. Michelle
We present Atacama Large Millimeter/Submillimeter Array CO(3-2) observations at 0.″3 resolution of He 2-10, a starburst dwarf galaxy and possible high-z galaxy analog. The warm dense gas traced by CO(3-2) is found in clumpy filaments that are kinematically and spatially distinct. The filaments have no preferred orientation or direction; this may i…
Saturn's Northern Auroras and Their Modulation by Rotating Current Systems During Late Northern Spring in Early 2014
Lamy, L.; Badman, S. V.; Cowley, S. W. H. +3 more
The Hubble Space Telescope imaged Saturn's northern ultraviolet auroras during February-June 2014, when Saturn's northern and southern magnetic perturbation fields were locked in antiphase and matched in rotation period ( 10.69 hr). During this coalescence period, we test for evidence of rotational modulation of the auroras using the latest rotati…
Studies of high-energy pulsars: The special case of PSR J1849-0001
Vleeschower Calas, Laila; Kaufmann, Sarah; Álvarez Ochoa, César +1 more
We present the results from the data analysis of the XMM-Newton observation (53.6 ks) on PSR J1849-0001. We studied in detail the X-ray emission of this pulsar and we found extended emission (up to ≈ 100 arcsec) from the Pulsar Wind Nebula (PWN), confirming that this is a case of a Pulsar/PWN system and strengthening the evidence that X-ray, hard …
On the origin of internal layers in comet nuclei
Li, Jian-Yang; Belton, Michael J. S.; Asphaug, Erik +1 more
We present an analysis of the layered structure on 67P/Churyumov-Gerasimenko' s Hathor cliff and propose a mechanism (self-sustaining, dual-mode propagation of amorphous to crystalline ice phase-change fronts into the nucleus interior) for its origin. If this is a viable mechanism, the strata must be geologically young (∼106 y). The Hat…