Search Publications
Angular correlation functions of X-ray point-like sources in the full exposure XMM-LSS field
Chiappetti, L.; Pierre, M.; Gosset, E. +8 more
Aims: Our aim is to study the large-scale structure of different types of AGN using the medium-deep XMM-LSS survey.
Methods: We measure the two-point angular correlation function of 5700 and 2500 X-ray point-like sources over the 11 sq. deg. XMM-LSS field in the soft (0.5-2 keV) and hard (2-10 keV) bands. For the conversion from the angu…
Newly Discovered Global Temperature Structures in the Quiet Sun at Solar Minimum
Landi, Enrico; Gombosi, Tamas I.; Frazin, Richard A. +3 more
Magnetic loops are building blocks of the closed-field corona. While active region loops are readily seen in images taken at EUV and X-ray wavelengths, quiet-Sun (QS) loops are seldom identifiable and are therefore difficult to study on an individual basis. The first analysis of solar minimum (Carrington Rotation 2077) QS coronal loops utilizing a…
Dependence of solar proton events on their associated activities: Coronal mass ejection parameters
Moon, Y. -J.; Gopalswamy, N.; Park, J.
In this study we have examined the occurrence probability of solar proton events (SPEs) and their peak fluxes depending on coronal mass ejection (CME) parameters, linear speed (V), angular width (AW), and location (L). For this we used the NOAA SPE list and their associated CME data from 1997 to 2006. We found that the probability strongly depends…
The Distance to M101 Hosting Type Ia Supernova 2011fe Based on the Tip of the Red Giant Branch
Lee, Myung Gyoon; Jang, In Sung
We present a new determination of the distance to M101, host of the Type Ia supernova (SN Ia) 2011fe, based on the tip of the red giant branch (TRGB) method. Our determination is based on Hubble Space Telescope archival F555W and F814W images of nine fields within the galaxy. Color-magnitude diagrams of arm-free regions in all fields show a promin…
Atomic oxygen on the Venus nightside: Global distribution deduced from airglow mapping
Montmessin, F.; Bertaux, J. -L.; Drossart, P. +3 more
The Visible and Infra-Red Thermal Imaging Spectrometer (VIRTIS) instrument on board the Venus Express spacecraft has measured the O 2(a 1Δ) nightglow distribution at 1.27 µm in the Venus mesosphere for more than two years. Nadir observations have been used to create a statistical map of the emission on Venus nightside. …
Evidence of Photoevaporation and Spatial Variation of Grain Sizes in the Orion 114-426 Protoplanetary Disk
Ricci, L.; Miotello, Anna; Robberto, Massimo +1 more
Deep Hubble Space Telescope broadband images taken with Advanced Camera for Surveys (ACS) and WFPC2 of the giant (~1000 AU diameter) dark silhouette proplyd 114-426 in the Orion Nebula show that this system is tilted, asymmetric, warped, and photoevaporated. The exquisite angular resolution of ACS allows us to map the distribution of dust grains a…
Numerical simulation of the effects of a solar energetic particle event on the ionosphere of Mars
Simon Wedlund, C.; Haider, S. A.; Withers, Paul +5 more
We investigate the ionospheric effects of a solar energetic particle (SEP) event at Mars, specifically the 29 September 1989 event. We use its energy spectrum and a steady state ionospheric model to simulate vertical profiles of ion and electron densities. The ionospheric response to this large event would have been readily observable. It caused e…
Revealing a ring-like cluster complex in a tidal tail of the starburst galaxy NGC 2146
Bastian, N.; Larsen, S. S.; Gallagher, J. S. +9 more
We report the discovery of a ring-like cluster complex in the starburst galaxy NGC 2146. The Ruby Ring, so named due to its appearance, shows a clear ring-like distribution of star clusters around a central object. It is located in one of the tidal streams that surround the galaxy. NGC 2146 is part of the Snapshot Hubble U-band Cluster Survey (SHU…
The formation of small cones in Isidis Planitia, Mars through mobilization of pyroclastic surge deposits
Ghent, Rebecca R.; Anderson, Steven W.; Pithawala, Taronish M.
We investigate the distinctive distribution and pattern of subkilometer-sized cones in Isidis Planitia, and their relationship to the material that fills the basin. We observe that: (1) the cones show uniform size, spacing, and morphology across the entire basin; (2) they have large central depressions (relative to cone basal diameters) that are g…
Secular Changes in Eta Carinae's Wind 1998-2011
Walter, Frederick M.; Humphreys, Roberta M.; Davidson, Kris +4 more
Stellar wind-emission features in the spectrum of eta Carinae have decreased by factors of 1.5-3 relative to the continuum within the last 10 years. We investigate a large data set from several instruments (STIS, GMOS, UVES) obtained between 1998 and 2011 and analyze the progression of spectral changes in direct view of the star, in the reflected …