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Kinematics of gas and stars in the circumnuclear star-forming ring of NGC3351
Terlevich, Roberto; Terlevich, Elena; Díaz, Ángeles I. +2 more
We have measured gas and stellar velocity dispersions in five circumnuclear star-forming regions (CNSFRs) and the nucleus of the barred spiral galaxy NGC3351. The stellar dispersions have been obtained from high-resolution spectra of the CaII triplet (CaT) lines at λλ8494, 8542, 8662Å, while the gas velocity dispersions have been measured by Gauss…
XMM-Newton study of 0.012 < z < 0.024 groups - I. Overview of the IGM thermodynamics
Finoguenov, A.; Ponman, T. J.; Osmond, J. P. F. +1 more
We study the thermodynamic properties of the hot gas in a sample of groups in the 0.012-0.024 redshift range, using XMM-Newton observations. We present measurements of temperature, entropy, pressure and iron abundance. Non-parametric fits are used to derive the mean properties of the sample and to study dispersion in the values of entropy and pres…
The Galaxy Luminosity Function at z ~= 1 in the HUDF: Probing the Dwarf Population
Panagia, N.; di Serego Alighieri, S.; Moustakas, L. A. +10 more
We present a catalog of spectrophotometric redshifts for 1308 galaxies from the Grism ACS Program for Extragalactic Science (GRAPES) observations with the Hubble Space Telescope. These low-resolution spectra between 6000 Å and 9500 Å are supplemented with U, J, H, and Ks data from various facilities, resulting in redshifts computed with…
Presence of dust with a UV bump in massive, star-forming galaxies at 1 < z < 2.5
Pannella, M.; Noll, S.; Pierini, D. +1 more
Aims:Fundamental properties of the extinction curve, like the slope in the rest-frame ultraviolet (UV) and the presence/absence of a broad absorption excess centred at 2175 Å (the UV bump), are investigated for a sample of 108 massive, star-forming galaxies at 1 < z < 2.5, selected from the FDF Spectroscopic Survey, the K20 survey, and the G…
A survey of the Wolf-Rayet population of the barred, spiral galaxy NGC 1313
Crowther, P. A.; Hadfield, L. J.
We present a VLT/FORS1 survey of Wolf-Rayet (WR) stars in the spiral galaxy NGC 1313. In total, 94 WR candidate sources have been identified from narrow-band imaging. Of these, 82 have been spectroscopically observed, for which WR emission features are confirmed in 70 cases, one of which also exhibits strong nebular He IIλ4686 emission. We also de…
New Physical Insight on the Changes in Magnetic Topology during Coronal Mass Ejections: Case Studies for the 2002 April 21 and August 24 Events
Lugaz, Noé; Roussev, Ilia I.; Sokolov, Igor V.
In order to investigate the dynamics of the coronal mass ejections on 2002 April 21 and August 24, we performed a series of numerical simulations with an ad hoc driver for the eruptions. The resulting evolution of the solar corona for each event was followed by means of three-dimensional MHD simulations. We used SOHO MDI data to set realistic boun…
Solar wind Cluster observations: Turbulent spectrum and role of Hall effect
Alexandrova, O.; Carbone, V.; Veltri, P. +1 more
Turbulent spectrum of magnetic fluctuations in the solar wind nearly follows Kolmogorov's law ∼f below the ion cyclotron frequency fci. Above this frequency, the observed steeper power law is believed to be a 'dissipative range' of the solar wind turbulence. In this paper we analyze magnetic field fluctuations measured onboard Cluster, …
Low-Mass X-Ray Binaries and Globular Clusters in Centaurus A
Sarazin, Craig L.; Jordán, Andrés; Raychaudhury, Somak +19 more
We present results of Hubble Space Telescope and Chandra X-Ray Observatory observations of globular clusters (GCs) and low-mass X-ray binaries (LMXBs) in the central regions of Centaurus A. Out of 440 GC candidates, we find 41 host X-ray point sources that are most likely LMXBs. We fit King models to our GC candidates in order to measure their str…
Color, Rotation, Age, and Chromospheric Activity Correlations in Late-Type Main-Sequence Stars
Cassatella, Angelo; Cardini, Daniela
A study of the rotation-activity-age relationships in a large sample of single late-type main-sequence stars is carried out, based on rotation period data from the literature, on our measurements of the Mg II k line chromospheric flux in IUE high-resolution spectra, and on Hipparcos parallaxes. The analysis of the rotation period data of open clus…
Properties of prominence fine-structure threads derived from SOHO/SUMER hydrogen Lyman lines
Heinzel, P.; Anzer, U.; Schmieder, B. +2 more
Context: The SOHO/SUMER observations provide us for the first time with the prominence spectra in the Lyman-α line outside the attenuator together with the higher members of the hydrogen Lyman series.
Aims: We derive the prominence fine-structure thread properties by comparing the SOHO/SUMER hydrogen Lyman series observations with the syntheti…