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The nature of the ghost cavity in the NGC 741 group
Babul, Arif; Raychaudhury, Somak; Ponman, Trevor J. +4 more
We discuss the effects of energy injection into the intragroup medium of the group of galaxies associated with NGC 741. The X-ray emission reveals a large bubble, which in the absence of a currently bright central radio source may have been inflated by a previous cycle of nuclear activity. If the bubble is filled with a light, relativistic fluid, …
Thermal electron periodicities at 20RS in Saturn's magnetosphere
André, N.; Lewis, G. R.; Coates, A. J. +6 more
Cassini fields and particles observations show clear evidence of periodic phenomena in Saturn's magnetosphere. Periodicities have been observed in kilometric radio emissions, total electron density (in the inner magnetosphere), magnetic fields, and energetic particles (in the outer magnetosphere). In this letter the first analysis of periodicities…
The Peculiar Globular Cluster System of the s0 Galaxy NGC 7457
Brodie, Jean P.; Strader, Jay; Chomiuk, Laura
We present Hubble Space Telescope photometry and Keck spectroscopy of globular clusters (GCs) in the nearby S0 galaxy NGC 7457. The V - I color-magnitude diagram of GCs lacks the clear bimodality present in most early-type galaxies; there may be a significant population of intermediate-color objects. Of 13 spectroscopically observed GCs, two are u…
Intensity oscillations observed with Hinode near the south pole of the Sun: leakage of low frequency magneto-acoustic waves into the solar corona
Srivastava, A. K.; Dwivedi, B. N.; Zaqarashvili, T. V. +1 more
Aims: We study intensity oscillations in the solar chromosphere and corona, above a quiet-Sun magnetic network.
Methods: We analyse the time series of He II 256.32 Å, Fe XI 188.23 Å and Fe XII 195.12 Å spectral lines, observed close to the south pole, by the EUV Imaging Spectrometer (EIS), onboard Hinode. We use a standard wavelet tool, to pro…
On the Magnetic Structure of the Solar Transition Region
Judge, Philip; Centeno, Rebecca
We examine the hypothesis that cool loops dominate emission from solar transition region plasma below temperatures of 2 × 105 K. We compare published VAULT images of H Lyα, a lower transition region line, with nearly contemporaneous magnetograms from Kitt Peak, obtained during the second flight (VAULT-2) on 2002 June 14. The measured su…
Very Large Array Observations of Galactic Center OH 1720 MHz Masers in Sagittarius A East and in the Circumnuclear Disk
Sjouwerman, Loránt O.; Pihlström, Ylva M.
We present Very Large Array (VLA) radio interferometry observations of the 1720 MHz OH masers in the Galactic center (GC). Most 1720 MHz OH masers arise in regions where the supernova remnant Sgr A East is interacting with the interstellar medium. The majority of the newly found 1720 MHz OH masers are located to the northeast, independently indica…
Emission-Line Galaxies from the Pears Hubble Ultra Deep Field: a 2d Detection Method and First Results
Hathi, Nimish P.; Koekemoer, Anton M.; Gardner, Jonathan P. +11 more
The Hubble Space Telescope Advanced Camera for Surveys grism Probing Evolution And Reionization Spectroscopically (PEARS) survey provides a large dataset of low-resolution spectra from thousands of galaxies in the GOODS north and south fields. One important subset of objects in these data is emission-line galaxies (ELGs), and we have investigated …
Photometric Oscillations of Low-Luminosity Red Giant Stars
Gilliland, Ronald L.
I present details of the variations of several hundred red giant stars on timescales of a few hours to a few days from Hubble Space Telescope (HST) observations of a low-extinction galactic bulge sample from an intensive seven-day campaign. Variations in the red giants are shown to be a strong function of position within the color-magnitude diagra…
Near-surface heating on Enceladus and the south polar thermal anomaly
Nimmo, F.; Roberts, J. H.
Strike-slip motion is predicted to be a consequence of diurnal tidal stresses in most satellites of the outer solar system. Such motion can lead to near-surface heating through friction or viscous dissipation. Here we discuss the effect of near-surface shear heating on convection in the underlying ice shells of icy satellites. We present models of…
Electron trapping around a magnetic null
Escoubet, C. P.; Dandouras, I.; Glassmeier, K. -H. +18 more
Magnetic reconnection is an important process in astrophysical, space and laboratory plasmas. The magnetic null pair structure is theoretically suggested to be a crucial feature of the three-dimensional magnetic reconnection. The physics around the null pair, however, has not been explored in combination with the magnetic field configuration deduc…