Search Publications
Polar Coronal Holes During Solar Cycles 22 and 23
Woch, J.; Zhang, Jun; Solanki, S.
Data from the Solar Wind Ion Composition Spectrometer (SWICS) on Ulysses and synoptic maps from Kitt Peak are used to analyze the polar coronal holes of solar activity cycles 22 and 23 (from 1990 to end of 2003). In the beginning of the declining phase of solar cycles 22 and 23, the north polar coronal holes (PCHs) appear about one year earlier th…
The absolute magnitude of K0V stars from Hipparcos data using an analytical treatment of the Malmquist bias
Butkevich, A. G.; Teerikorpi, P.; Berdyugin, A. V.
We calculate the average absolute magnitude for Hipparcos single K0V stars, using a theoretical curve for the distance-dependent Malmquist bias in the data. This method is shown to be well applicable to stellar data with good parallaxes and gives results in agreement with a previous study that used another treatment of the bias developed in extrag…
Reply to comment by M. L. Kaiser et al. on ``Rotation rate of Saturn's interior from magnetic field observations''
Dougherty, Michele K.; Russell, Christopher T.; Smith, Edward J. +1 more
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Vigorous star formation in a bulge-dominated extremely red object at z= 1.34
Simpson, Chris; Cotter, Garret; Bolton, Rosemary C.
We present near-infrared (near-IR) spectroscopy of three extremely red objects (EROs) using the OHS/CISCO spectrograph at the Subaru Telescope. One target exhibits a strong emission line, which we identify as Hα at z= 1.34. Using new and existing ground-based optical and near-IR imaging, and archival Hubble Space Telescope imaging, we argue that t…
Energetic Particles in the Heliosphere
Heber, Bernd
The heliosphere is the region around the Sun that is filled by the solar wind and its embedded magnetic field. The interaction of the supersonic solar wind with the local interstellar medium leads to a transition from supersonic to subsonic speeds at the heliospheric termination shock. The latter is regarded to be the source of the anomalous compo…
Multiple flux rope events at the magnetopause observations by TC-1 on 18 March 2004
Wei, Y.; Zhang, T. L.; Dandouras, I. +7 more
From 23:10 to 23:50 UT on 18 March 2004, the Double Star TC-1 spacecraft detected eight flux ropes at the outbound crossing of the southern dawnside magnetopause. A notable guide field existed inside all ropes. In the mean time the Cluster spacecraft were staying in the magnetosheath and found that the events occurred under the condition of southw…
Debris Discs Around Stars: The 2004 ISO Legacy
de Muizon, Marie Jourdain
Debris discs around stars were first discovered by the Infrared Astronomical Satellite (IRAS) in 1983. For the first time material orbiting another star than the Sun, but distinct from a circumstellar envelope, was observed through its far infrared emission. This major discovery motivated astronomers to investigate those discs by further analyzing…
New variable and multiple stars in the lower part of the Cepheid instability strip
Lampens, P.; Fremat, Y.; van Cauteren, P. +1 more
We obtained high-resolution spectra for 33 A-type stars during 4 consecutive nights. All our targets are Hipparcos program stars located in the lower part of the Cepheid instability strip which show hints for variability in radial velocity of a yet unidentified nature. CCD photometry was acquired for some of the most promising candidates and used …
Coronal oscillation above a supergranular cell of the quiet Sun chromospheric network?
Peter, H.; Gontikakis, C.; Dara, H. C.
We have detected an oscillation in the low corona, using a raster of the SUMER EUV spectrograph in the Ne viii, 770 Å line formed at about 700 000 K. The oscillation was found in the Ne viii Doppler map above the interior of a supergranular cell of the chromospheric network in the quiet Sun, while it is absent in line radiance. The photospheric ma…
Radiation hardness studies for the X-ray Solar Monitor (XSM) onboard the ESA SMART-1 mission
Andersson, H.; Alha, L.; Huovelin, J. +7 more
The X-ray detection performance of the X-ray Solar Monitor (XSM, onboard the ESA SMART-1 satellite) Si pin -detector was studied after exposure to several types of radiation typical of the space environment (i.e. protons, electrons and γ -radiation). The detector withstands the tested radiation types at the expected mission dose levels. Hence, the…