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The distance to the Galactic center determined by OB stars
Branham, Richard L.
The OB stars are concentrated near the Galactic plane and should permit a determination of the distance to the Galactic center. van Leeuwen's new reduction of the Hipparcos catalog provides, after 824 Gould belt stars have been excluded, 6288 OB stars out to 1 kpc and Westin's compilation an additional 112 stars between 1 kpc and 3 kpc. The reduct…
Power spectrum analysis of limb and disk spicule using Hinode Ca H-line broadband filter
Tavabi, E.
We present observations of a solar quiet region obtained using the Hinode Solar Optical telescope (SOT) in the Ca II H-line with broadband filter taken on November 2006. We study off-limb and on-disk spicules to find a counterpart of the limb spicule on the disk. This investigation shows a strong correspondence between the limb and near limb spicu…
Searching for a gas cloud surrounding the WASP-18 planetary system
Fossati, L.; Kochukhov, O.; Bohlender, D. +5 more
Near-UV (NUV) Hubble Space Telescope (HST) observations of the extreme hot-Jupiter WASP-12b revealed the presence of diffuse exospheric gas extending beyond the planet's Roche lobe. Furthermore the NUV observations showed a complete lack of the normally bright core emission of the Mg II h&k resonance lines, in agreement with the measured anomalous…
The ultraviolet radiation environment in the habitable zones around low-mass exoplanet host stars
Loyd, R. O. Parke; France, Kevin; Linsky, Jeffrey L.
The EUV (200–911 Å), FUV (912–1750 Å), and NUV (1750–3200 Å) spectral energy distribution of exoplanet host stars has a profound influence on the atmospheres of Earth-like planets in the habitable zone. The stellar EUV radiation drives atmospheric heating, while the FUV (in particular, Lyα) and NUV radiation fields regulate the atmospheric chemist…
Observation of kink waves and their reconnection-like origin in solar spicules
Ebadi, H.; Ghiassi, M.
We analyze the time series of Ca II H-line obtained from Hinode/SOT on the solar limb. We follow three cases of upwardly propagating kink waves along a spicule and inverted Y-shaped structures at the cusp of it. The time-distance analysis shows that the axis of spicule undergos quasi-periodic transverse displacement at different heights from the p…
The local ISM in three dimensions: kinematics, morphology and physical properties
Redfield, Seth; Linsky, Jeffrey L.
We summarize the results of our long-term program to study the kinematics, morphology, and physical properties of warm partially ionized interstellar gas located within 100 pc of the Sun. Using the Space Telescope Imaging Spectrograph (STIS) and other spectrographs on the Hubble Space Telescope (HST), we measure radial velocities of neutral and si…
Oscillations in solar jets observed with the SOT of Hinode: viscous effects during reconnection
Koutchmy, S.; Tavabi, E.
Transverse oscillatory motions and recurrence behavior in the chromospheric jets observed by Hinode/SOT are studied. A comparison is considered with the behavior that was noticed in coronal X-ray jets observed by Hinode/XRT. A jet like bundle observed at the limb in Ca II H line appears to show a magnetic topology that is similar to X-ray jets (i.…
On vortex motion in chromospheric network boundaries
Tavabi, E.
A large percent of spicules shows a surge-like behavior on the solar limb, supporting a multi-component model with twisted threads. The counterpart of limb spicules foot-points is investigated on the disk, and this re-examination indicates that the interpretation of transverse motion of off-limb spicules could directly be related to rotational mot…
A study of line widths and kinetic parameters of ions in the solar corona
Wu, D. J.; Zhao, G. Q.; Wang, C. B.
Solar extreme-ultraviolet (EUV) lines emitted by highly charged ions have been extensively studied to discuss the issue of coronal heating and solar wind acceleration. Based on observations of the polar corona by the SUMER/SOHO spectrometer, this paper investigates the relation between the line widths and kinetic parameters of ions. It is shown th…
The most compact bright radio-loud AGN—I. A new target sample selected for the space VLBI
Frey, Sándor; An, Tao; Wu, Xiaocong
We investigated the archival ground-based VLBI images of the extragalactic radio sources included in both the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck catalogues, and selected 49 bright and compact sources as potential targets for space Very Long Baseline Interferometry (VLBI) observations at mm wavelengths. These sources have a …