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RR Lyrae stars in M31 globular clusters: B514
Clementini, G.; Marconi, M.; Cacciari, C. +8 more
We present preliminary results of a variable star search in the metal-poor globular cluster B514 of the Andromeda galaxy (M31), based on Hubble Space Telescope Wide Field Planetary Camera 2 and Advanced Camera for Surveys observations. A large number of RR Lyrae stars have been identified for the first time in a globular cluster of M31. The averag…
EUV spectral energy distribution of quasars restored from associated absorbers
Reimers, D.; Levshakov, S. A.; Agafonova, I. I. +2 more
Aims: We reconstruct the spectral shape of the quasar ionizing radiation in the extreme-UV range (1 Ryd ≤ E < 10 Ryd) from the analysis of narrow absorption lines (NAL) of the associated systems.
Methods: The computational technique for inverse spectroscopic problems - a Monte Carlo Inversion augmented by the spectral shape recovering proce…
Structure of the near-Earth plasma sheet during tailward flows
Balogh, A.; Nakamura, R.; Fujimoto, M. +10 more
A detailed analysis of successive tailward flow bursts in the near-Earth magnetotail (X~-19 RE) plasma sheet is performed on the basis of in-situ multi-point observations by the Cluster spacecraft on 15 September 2001. The tailward flows were detected during a northward IMF interval, 2.5 h after a substorm expansion. Each flow burst (V<…
Modeling PSBL high speed ion beams observed by Cluster and Double Star
Bosqued, Jean-Michel; El-Alaoui, Mostafa; Walker, Raymond J. +3 more
On October 8, 2004, the Cluster and Double Star spacecraft crossed the near-Earth (12 19 RE) magnetotail neutral sheet during the recovery phase of a small, isolated substorm. Although they were separated in distance by ∼7 RE and in time by ∼30 min, both Cluster and Double Star observed steady, but highly structured Earthward…
The Non-Thermal Radio Jet Toward the NGC 2264 Star Formation Region
Rodríguez, Luis F.; Trejo, Alfonso
We report sensitive VLA 3.6 cm radio observations toward the head of the Cone Nebula in NGC 2264, made in 2006. The purpose of these observations was to study a non-thermal radio jet recently discovered, which appears to emanate from the head of the Cone Nebula. The jet is highly polarized, with well-defined knots, and one-sided. Comparison of our…
Confirmation of the binary status of Chamaeleon Hα 2 - a very young low-mass binary in Chamaeleon
Neuhäuser, R.; Schmidt, T. O. B.; Vogt, N. +3 more
Context: Neuhäuser & Comerón (1998, Science, 282, 83; 1999, A&A, 350, 612) presented direct imaging evidence, as well as first spectra, of several young stellar and sub-stellar M6- to M8-type objects in the Cha I dark cloud. One of these objects is Cha Hα 2, classified as brown dwarf candidate in several publications and suggested as possi…
Refining the Parallax in Visual Double Stars Using Orbital and Spectral Data: Application to the System of the K0 Giants, A 1808
Docobo, J. A.; Andrade, M.; Tamazian, V. S. +2 more
In this paper, we show how Hipparcos parallaxes of distant visual binaries (πHip <~ 10 mas) can be refined. This is accomplished by using relevant orbital and spectral data. To this end, we study the pair of K0 giants, A 1808. A revised orbit of this system is presented that was calculated by taking into account a set of interferomet…
RX J1648.7+6109: Witnessing the Formation of a Massive Group/Poor Cluster and Its Brightest Galaxy
Mulchaey, John S.; Lubin, Lori M.; Jeltema, Tesla E.
Using deep Chandra and optical spectroscopic observations, we investigate an intriguing young massive group, RX J1648.7+6109, at z = 0.376, and we combine these observations with previous measurements to fit the scaling relations of intermediate-redshift groups and poor clusters. RX J1648 appears to be in an early stage of formation; while it foll…
XMM-Newton X-ray and optical monitor far UV observations of NGC 7070A and ESO 2400100 shell galaxies
Marino, A.; Trinchieri, G.; Rampazzo, R. +3 more
Context: Shell galaxies are considered to be the debris of recent accretion/merging episodes. Their high frequency in low density environments suggests that these episodes could drive the secular evolution of at least some fraction of the early-type galaxy population.
Aims: We present XMM-Newton X-ray observations of two shell galaxies, NGC 70…
The Cygnus region: A laboratory for nucleosynthesis
Martin, Pierrick; Knödlseder, Jürgen; Meynet, Georges
We have observed the Cygnus region in the gamma-ray decay lines of 26Al and 60Fe with the INTEGRAL/SPI spectrometer. A study of the morphology of the 1809 keV emission from 26Al suggests an emission region centered about the massive star cluster Cyg OB2, with a characteristic size between 6° and 9° or possibly high…