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The T Tauri Star Population of the Young Cluster NGC 2264
Simon, Theodore; Dahm, S. E.
An Hα emission survey of the young cluster NGC 2264 in the Mon OB1 association resulted in the detection of 490 Hα emission stars in a 25'×40' field approximately centered between the O7 V multiple star S Mon and the Cone Nebula. The survey was carried out with the wide-field grism spectrograph (WFGS) on the University of Haw…
Magnetic field variations in the Jovian magnetotail induced by solar wind dynamic pressure enhancements
Yokoyama, Takaaki; Tao, Chihiro; Kataoka, Ryuho +2 more
In order to understand the response of the Jovian magnetosphere to solar wind dynamic pressure enhancements, we investigate magnetic field variations observed by the Galileo spacecraft. The lack of solar wind monitoring just upstream of the Jovian magnetosphere is overcome by simulating a one-dimensional magnetohydrodynamic (MHD) propagation of th…
The abundance discrepancy - recombination line versus forbidden line abundances for a northern sample of galactic planetary nebulae
Barlow, M. J.; Liu, X. -W.; Wesson, R.
We present deep optical spectra of 23 galactic planetary nebulae, which are analysed in conjunction with archival infrared and ultraviolet spectra. We derive nebular electron temperatures based on standard collisionally excited line (CEL) diagnostics as well as the hydrogen Balmer jump and find that, as expected, the Balmer jump almost always yiel…
Spatially resolved microwave pulsations of a flare loop
Melnikov, V. F.; Nakariakov, V. M.; Shibasaki, K. +1 more
A microwave burst with quasi-periodic pulsations was studied with high spatial resolution using observations with the Nobeyama Radioheliograph (NoRH). We found that the time profiles of the microwave emission at 17 and 34 GHz exhibit quasi-periodic (with two well defined periods P_1= 14-17 s and P_2= 8-11 s) variations of the intensity at differen…
Deep ACS Imaging of the Halo of NGC 5128: Reaching the Horizontal Branch
Greggio, Laura; Peng, Eric W.; Rejkuba, Marina +2 more
Using the Hubble Space Telescope (HST) Wide Field Camera (WFC) of the Advanced Camera for Surveys (ACS), we have obtained deep (V, I) photometry of an outer halo field in NGC 5128, to a limiting magnitude of I~=29. Our photometry directly reveals the core helium burning stellar population (the ``red clump'' or horizontal branch) in a giant E/S0 ga…
Discovery of the Accretion-powered Millisecond X-Ray Pulsar IGR J00291+5934
Chakrabarty, Deepto; Galloway, Duncan K.; Markwardt, Craig B. +2 more
We report on observations of the sixth accretion-powered millisecond pulsar, IGR J00291+5934, with the Rossi X-Ray Timing Explorer. The source is a faint recurrent X-ray transient initially identified by the International Gamma-Ray Astrophysics Laboratory. The 599 Hz (1.67 ms) pulsation had a fractional rms amplitude of 8% in the 2-20 keV range, a…
Evolution of X-ray emission from young massive star clusters
Oskinova, L. M.
The evolution of X-ray emission from young massive star clusters is modelled, taking into account the emission from the stars as well as from the cluster wind. It is shown that the level and character of the soft (0.2-10 keV) X-ray emission change drastically with cluster age and are tightly linked with stellar evolution. Using the modern X-ray ob…
The Planetary Fourier Spectrometer (PFS) onboard the European Mars Express mission
Grigoriev, A.; Rodrigo, R.; Rodriguez, J. +44 more
The Planetary Fourier Spectrometer (PFS) for the Mars Express mission is an infrared spectrometer optimised for atmospheric studies. This instrument has a short wave (SW) channel that covers the spectral range from 1700 to 8200.0cm-1 (1.2- 5.5µm) and a long-wave (LW) channel that covers 250- 1700cm-1 (5.5- 45µm). …
On the nature of nearby GRB/SN host galaxies
Sollerman, J.; Östlin, G.; Fynbo, J. P. U. +3 more
We present and discuss optical diagnostics of the low redshift ( z < 0.2) galaxies that are known to have hosted supernovae associated with γ-ray bursts (GRBs). The three galaxies are all actively star forming sub-luminous ( L < L⋆) galaxies with relatively low metallicities ( Z ≲ Z⊙). We find no evidence for substantia…
On the Nature of Dark Extreme Ultraviolet Structures Seen by SOHO/EIT and TRACE
Heinzel, P.; Anzer, U.
Spectral lines in the extreme ultraviolet (EUV) observed on the Sun can originate either from the hot corona or the cooler chromosphere to corona transition region. In the present paper we concentrate on coronal lines and in particular on iron lines at 171, 195, and 284 Å, which have been frequently observed by the Solar and Heliospheric Observato…