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The Low-Mass Pre-Main-Sequence Population of the Stellar Association LH 52 in the Large Magellanic Cloud Discovered with Hubble Space Telescope WFPC2 Observations
Henning, Th.; Brandner, W.; Gouliermis, D.
We report on the serendipitous discovery of ~500 low-mass candidate pre-main-sequence (PMS) stars in the vicinity of the stellar association LH 52 in the Large Magellanic Cloud. We present evidence that the red faint sequence of these stars seen in the CMD of LH 52 from Hubble Space Telescope (HST) WFPC2 observations belongs only to the associatio…
Detailed Spectral Study of an Ultra-Luminous Compact X-Ray Source, M81 X-9, in the Disk-Dominated State
Makishima, Kazuo; Tsunoda, Naoko; Kubota, Aya +3 more
We report on the results of detailed spectral studies of an ultra-luminous X-ray source (ULX), M81 X-9 (Holmberg IX X-1), conducted with XMM-Newton on 2001 April 22 and with ASCA on 1999 April 6. On both occasions, the source showed an unabsorbed 0.5-10keV luminosity of ∼2 × 1040erg s-1 (assuming a distance of 3.4Mpc) and a s…
Solar Wind Electric Fields in the Ion Cyclotron Frequency Range
Bale, S. D.; Horbury, T. S.; Reme, H. +2 more
Measurements of fluctuations of electric fields in the frequency range from a fraction of 1 to 12.5 Hz are presented and corrected for the Lorentz transformation of magnetic fluctuations to give the electric fields in the plasma frame. The electric fields are large enough to provide the dominant force on the ions of the solar wind in the region ne…
Automatic Detection and Classification of Coronal Mass Ejections
Jing, Ju; Wang, Haimin; Qu, Ming +1 more
We present an automatic algorithm to detect, characterize, and classify coronal mass ejections (CMEs) in Large Angle Spectrometric Coronagraph (LASCO) C2 and C3 images. The algorithm includes three steps: (1) production running difference images of LASCO C2 and C3; (2) characterization of properties of CMEs such as intensity, height, angular width…
The Influence of Magnetic Field on Oscillations in the Solar Chromosphere
Mathioudakis, Mihalis; Bloomfield, D. Shaun; McAteer, R. T. James +1 more
Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photospheric magnetic flux measured by the Michelson Doppler Interferometer on the Solar Heliospheric Observatory to study wave behavior in differing magnetic environments. Wa…
Resolved Hubble space spectroscopy of ultracool binary systems
Martín, E. L.; Bouy, H.; Brandner, W. +4 more
Using the low-resolution mode of the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST), we obtain spectra from 20 spatially-resolved, ultracool dwarfs, eighteen of which belong to nine very low-mass binary systems with known angular separations in the range 0.37 arcsec-0.098 arcsec. For these dwarfs, we derive the…
Star forming galaxies at z ≈ 6 and reionization
Ellis, Richard; Bunker, Andrew; Lacy, Mark +3 more
We determine the abundance of i'-band drop-outs in the HST/ACS GOODS surveys and the Hubble Ultra Deep Field (UDF). The majority of these sources are likely to be z ≈ 6 galaxies whose flux decrement between the F775W i'-band and F850LP z'-band arises from Lyman- α absorption. We have shown with Keck/DEIMOS and Gemini/GMOS spectroscopy that this te…
OMEGA/Mars Express: Visual channel performances and data reduction techniques
Gondet, B.; Langevin, Y.; Poulet, F. +4 more
In this paper we discuss the on-ground and in-flight performances of the visual channel of the OMEGA instrument on board the European mission Mars Express. OMEGA is a mapping spectrometer designed for mineralogical and atmospheric investigation of Mars. This work aims to be a guide to future users for the analysis of the OMEGA data. We give a deta…
Evidence for T Tauri-like emission in the EXor V1118 Ori from near-IR and X-ray data
Larionov, V. M.; Arkharov, A. A.; Puccetti, S. +6 more
Aims.We present a near-IR study of the EXor variable V1118 Ori, performed by following a slightly declining phase after a recent outburst. In particular, the near-IR (0.8-2.3 µm) spectrum, obtained for the first time, shows a wide variety of emission features of the H I (Paschen and Brackett series), He I recombination, and CO overtone.
M…
Dwarf elliptical galaxies in Centaurus A group: stellar populations in AM 1339-445 and AM 1343-452
Rejkuba, M.; Da Costa, G. S.; Zoccali, M. +2 more
We study the red giant populations of two dE galaxies, AM 1339-445 and AM 1343-452, with the aim of investigating the number and luminosity of any upper asymptotic giant branch (AGB) stars present. The galaxies are members of the Centaurus A group (D ≈ 3.8 Mpc) and are classified as outlying (R ≈ 350 kpc) satellites of Cen A. The analysis is based…