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The early expansion of cluster cores
Bastian, N.; Smith, L. J.; Goodwin, S. P. +4 more
The observed properties of young star clusters, such as the core radius and luminosity profile, change rapidly during the early evolution of the clusters. Here we present observations of six young clusters in M51 where we derive their sizes using Hubble Space Telescope (HST) imaging and ages using deep Gemini-North spectroscopy. We find evidence f…
Spectropolarimetric Observation of an Emerging Flux Region: Triggering Mechanisms of Ellerman Bombs
Shibata, K.; Ueno, S.; Kitai, R. +6 more
A high spatial resolution observation of an emerging flux region (EFR) was made using a vector magnetograph and a Hα Lyot filtergraph with the Domeless Solar Telescope at Hida Observatory on 2006 October 22. In Hα wing images, we could see many Ellerman bombs (EBs) in the EFR. Observations in two modes, slit scan and slit fixed, were performed wit…
The Stellar Mass Distribution in the Giant Star Forming Region NGC 346
Tosi, M.; Sabbi, E.; Nota, A. +8 more
Deep F555W and F814W Hubble Space Telescope (HST ) Advanced Camera for Survey (ACS) images are the basis for a study of the present-day mass function (PDMF) of NGC 346, the largest active star-forming region in the Small Magellanic Cloud (SMC). We find a PDMF slope of Γ = -1.43 ± 0.18 in the mass range 0.8-60 Msun, in excellent agreemen…
Molecular Gas in NUclei of GAlaxies (NUGA). IX. The decoupled bars and gas inflow in NGC 2782
Tacconi, L. J.; Hunt, L. K.; Krips, M. +8 more
We present CO(1-0) and CO(2-1) maps of the starburst/Seyfert 1 galaxy NGC 2782 obtained with the IRAM interferometer, at 2.1 arcsec×1.5 arcsec and 0.7 arcsec×0.6 arcsec resolution respectively. The CO emission is aligned along the stellar nuclear bar of radius ~1 kpc, configured in an elongated structure with two spiral arms at high pitch angle ~9…
Circumstellar water vapour in M-type AGB stars: radiative transfer models, abundances, and predictions for HIFI
Olofsson, H.; Schöier, F. L.; Bergman, P. +2 more
Context: Surprisingly high amounts of H2O have recently been reported in the circumstellar envelope around the M-type asymptotic giant branch star W Hya. This has lead to the speculation that evaporation of icy cometary or planetary bodies might be an effective ongoing mechanism in such systems. However, substantial uncertainties remain, as the re…
A microlensing study of the accretion disc in the quasar MG 0414+0534
Wyithe, J. S. B.; Bate, N. F.; Floyd, D. J. E. +1 more
Observations of gravitational microlensing in multiply imaged quasars currently provide the only direct probe of quasar emission region structure on submicroarcsecond scales. The analyses of microlensing variability are observationally expensive, requiring long-term monitoring of lensed systems. Here, we demonstrate a technique for constraining th…
Distribution and escape of molecular hydrogen in Titan's thermosphere and exosphere
Yelle, R. V.; Volk, K.; Cui, J.
We present an in-depth study of the distribution and escape of molecular hydrogen (H2) on Titan, based on the global average H2 distribution at altitudes between 1000 and 6000 km, extracted from a large sample of Cassini/Ion and Neutral Mass Spectrometer (INMS) measurements. Below Titan's exobase, the observed H2 d…
SOHO/SUMER observations of prominence oscillation before eruption
Solanki, S. K.; Innes, D. E.; Chen, P. F.
Context: Coronal mass ejections (CMEs), as a large-scale eruptive phenomenon, often reveal some precursors in the initiation phase, e.g., X-ray brightening, filament darkening, etc., which are useful for CME modelling and space weather forecasting.
Aims: With the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectroscopic observa…
Cluster observations of an ion-scale current sheet in the magnetotail under the presence of a guide field
RèMe, H.; Fazakerley, A. N.; Klecker, B. +9 more
We report on Cluster observations of a thin current sheet interval under the presence of a strong ∣BY∣ during a fast earthward flow interval between 1655 UT and 1703 UT on 17 August 2003. The strong ∣BY∣ in the tail could be associated with a strong IMF ∣BY∣, but the large fluctuations in BY, not seen in…
Prevalence of High X-Ray Obscuring Columns among AGNs that Host H2O Masers
Tilak, Avanti; Greenhill, Lincoln J.; Madejski, Grzegorz
Of 104 AGNs known to exhibit H2O maser emission, X-ray data that enable estimation of column densities, or lower limits, are available for 42. Contributing to this, we report analysis of new and archival X-ray data for eight galaxies and collation of values for three more. Maser emission is indicative of large columns of cold gas, and i…