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The old globular cluster system of the dIrr galaxy NGC 1427A in the Fornax cluster
Infante, L.; Hilker, M.; Georgiev, I. Y. +5 more
We present a study of the old globular cluster (GC) population of the dwarf irregular galaxy NGC 1427A using multi-wavelength VLT observations in U,B,V,I, Hα and J bands under excellent observing conditions. We applied color and size selection criteria to select old GC candidates and made use of archival ACS images taken with the Hubble Space Tele…
Magnetic reconfiguration before the X 17 Solar flare of October 28 2003
Mandrini, C. H.; Schmieder, B.; Démoulin, P. +3 more
An active region (AR) NOAA 10486, which produced a large number of X-ray flares during October November 2003, was observed during a multi-wavelength campaign with ground based and space instruments. We focus our analysis on the observations of October 28, 2003. The magnetic field was observed with THEMIS (Na D1) and MDI (Ni I), the chromosphere wi…
Mira B Rejuvenated
Wood, Brian E.; Karovska, Margarita
Recent ultraviolet spectra from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) satellites demonstrate that UV line and continuum fluxes observed from Mira B are increasing back toward the levels that the International Ultraviolet Explorer (IUE) observed in 1979-1980 and 1990-1995, after having been found in a ve…
Searching for Annihilation Radiation from SN 1006 with SPI on INTEGRAL
Boggs, S. E.; Kalemci, E.; Milne, P. A. +1 more
Historical Type Ia supernovae are a leading candidate as the source of positrons observed through diffuse annihilation emission in the Galaxy. However, a search for annihilation emission from individual Type Ia supernovae was not possible before the improved sensitivity of INTEGRAL. The total 511 keV annihilation flux from individual SNe Ia, as we…
A Statistical Study of Transequatorial Loops
Zhang, Hongqi; Chen, Jie; Bao, Shudong
We identify 356 transequatorial loops (TLs) from the data set of Yohkoh Soft X-Ray Telescope (SXT) in the period of solar cycles 22 and 23. The classification of the TLs can be made on two bases. One is according to the magnetic polarities of the footpoints of TLs, and the other is according to the number of TLs in the same region. Based on the fi…
Extraordinarily Hot X-Ray Emission from the O9 Emission-Line Star HD 119682
Testa, Paola; Wolk, S. J.; Rakowski, Cara E. +1 more
We present new optical and X-ray observations to show that the X-ray source 1WGA J1346.5-6255 previously associated with the SNR G309.2-0.6 can be unequivocally identified with the emission-line star HD 119682 located in the foreground open cluster NGC 5281. Images from Chandra in the X-ray band as well as from Magellan in the narrow optical Hα ba…
A Photoionized Herbig-Haro Object in the Orion Nebula
Martin, P. G.; Blagrave, K. P. M.; Baldwin, J. A.
The spectra of Herbig-Haro objects are usually characteristic of ionization and excitation in shock-heated gas, whether an internal shock in an unsteady outflow or a bow shock interface with the interstellar medium. We examine the easternmost shock-the leading optically visible shock-of a Herbig-Haro outflow (HH 529) seen projected on the face of …
Vertical pressure profile of Titan—observations of the PPI/HASI instrument
Harri, Ari-Matti; Mäkinen, Teemu; Siili, Tero +2 more
The Huygens entry probe descended through the atmosphere of Titan and provided an excellent set of observations of the atmosphere and the surface of Titan. During the 150-min descent the Huygens Atmospheric Structure Instrument (HASI) observed a comprehensive set of variables, including pressure, temperature, density and atmospheric electricity. T…
Surface-brightness fluctuations in stellar populations. IAC-star models for the optical and near-IR wavelengths
Marín-Franch, A.; Aparicio, A.
Aims.A new theoretical calibration of surface-brightness fluctuations (SBF) for single age, single metallicity stellar populations is presented for the optical and near-IR broad-band filters, as well as for the HST WFPC2 and ACS filters.
Methods: .The IAC-star code is used. Two Padua and the Teramo stellar evolution libraries have been conside…
Chlorine in the Galactic Interstellar Medium: Revised f-Values with the Far Ultraviolet Spectroscopic Explorer and the Space Telescope Imaging Spectrograph
York, D. G.; Sonnentrucker, P.; Friedman, S. D.
Cl I is the atomic species most directly coupled to molecular hydrogen due to its chemistry. Its weakest lines are thereby probably the best tracer of optically thick H2 components in diffuse clouds. We report on the empirical determination of the oscillator strengths for four Cl I absorption lines predicted to be weak and often detecte…