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Properties of sunspots in cycle 23. I. Dependence of brightness on sunspot size and cycle phase
Solanki, S. K.; Martínez Pillet, V.; Krivova, N. A. +1 more
Aims:In this paper we investigate the dependence of umbral core brightness, as well as the mean umbral and penumbral brightness on the phase of the solar cycle and on the size of the sunspot.
Methods: Albregtsen & Maltby (1978, Nature, 274, 41) reported an increase in umbral core brightness from the early to the late phase of solar cycle f…
A Floor in the Solar Wind Magnetic Field
Cliver, E. W.; Svalgaard, L.
Long-term (~130 years) reconstruction of the interplanetary magnetic field (IMF) based on geomagnetic indices indicates that the solar wind magnetic field strength has a ``floor,'' a baseline value in annual averages that it approaches at each 11 yr solar minimum. In the ecliptic plane at 1 AU, the IMF floor is ~4.6 nT, a value substantiated by di…
The trigonometric parallax of the neutron star Geminga
Anderson, Jay; Walter, Frederick M.; Faherty, Jacqueline
We obtained a series of four observations of the isolated neutron star Geminga over an 18 month period using the Advanced Camera for Surveys (ACS) Wide Field Camera (WFC) on the Hubble Space Telescope in order to determine its trigonometric parallax. We find the parallax π=4.0±1.3 mas, corresponding to a distance to Geminga of 250
Spectrophotometric analysis of Ellerman bombs in the Ca II, Hα, and UV range
Schmieder, B.; Pariat, E.; Wang, S. +4 more
Context: Even if Ellerman bombs have been observed in the Hα line within emerging magnetic flux regions since the early 20th century, their origin and the mechanisms that lead to their formation have been strongly debated. Recently, new arguments in favor of chromospheric magnetic reconnection have been advanced. Ellerman bombs seem to be the sign…
On the Origin of Three Seismic Sources in the Proton-rich Flare of 2003 October 28
Zharkova, Valentina V.; Zharkov, Sergei I.
The three seismic sources, S1, S2, and S3, detected from MDI Dopplergrams using the time-distance (TD) diagram technique are presented with the locations, areas, and vertical and horizontal velocities of the visible wave displacements. Within the data cube of 120 Mm, the horizontal velocities and the wave propagation times vary slightly from sourc…
The GLARE Survey - II. Faint z ~ 6 Lyα line emitters in the HUDF
Bunker, Andrew J.; Glazebrook, Karl; Abraham, Roberto G. +6 more
The galaxy population at z ~ 6 has been the subject of intense study in recent years, culminating in the Hubble Ultra Deep Field (HUDF) - the deepest imaging survey yet. A large number of high-redshift galaxy candidates have been identified within the HUDF, but until now analysis of their properties has been hampered by the difficulty of obtaining…
Venus Monitoring Camera for Venus Express
Dierker, C.; Jaumann, R.; Keller, H. U. +28 more
The Venus Express mission will focus on a global investigation of the Venus atmosphere and plasma environment, while additionally measuring some surface properties from orbit. The instruments PFS and SPICAV inherited from the Mars Express mission and VIRTIS from Rosetta form a powerful spectrometric and spectro-imaging payload suite. Venus Monitor…
A Portrait of the Nucleus of Comet 67P/Churyumov-Gerasimenko
Toth, Imre; Lamy, Philippe L.; Gutiérrez, Pedro +5 more
In 2003, comet 67P/Churyumov-Gerasimenko was selected as the new target of the Rosetta mission as the most suitable alternative to the original target, comet 46P/Wirtanen, on the basis of orbital considerations even though very little was known about the physical properties of its nucleus. In a matter of a few years and based on highly focused obs…
Investigating the Nuclear Obscuration in Two Types of Seyfert 2 Galaxies
Shu, X. W.; Wang, J. X.; Jiang, P. +2 more
We build a large sample of Seyfert 2 galaxies (Sy2s) with both optical spectropolarimetric and X-ray data available, in which 29 of the Sy2s have a detection of polarized broad emission lines (PBLs) and 25 do not. We find that for luminous Sy2s with L[OIII>1041 ergs s-1, sources with PBLs have smaller X-ray abso…
The Plasma Environment of Comet 67P/Churyumov-Gerasimenko Throughout the Rosetta Main Mission
Alexander, C.; Combi, M. R.; Gombosi, T. I. +6 more
The plasma environment of comet 67P/Churyumov-Gerasimenko, the Rosetta mission target comet, is explored over a range of heliocentric distances throughout the mission: 3.25 AU (Rosetta instruments on), 2.7 AU (Lander down), 2.0 AU, and 1.3 AU (perihelion). Because of the large range of gas production rates, we have used both a fluid-based magnetoh…