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Variation of the full Sun hydrogen Lyman profiles through solar cycle 23
Vial, J. -C.; Wilhelm, K.; Curdt, W. +3 more
The hydrogen Lyman (Lyα, 121.267 nm and Lyβ, 102.572 nm) lines are important contributors to the solar extreme ultra violet (EUV) flux which illuminates the upper Earth’s atmosphere. From high resolution spectral observations performed with the solar ultraviolet measurement of emitted radiations (SUMER) spectrometer on the Solar and Heliospheric O…
Rotation periods for stars of the TW Hydrae association: the evidence for two spatially and rotationally distinct pre-main-sequence populations
Lawson, Warrick A.; Crause, Lisa A.
We have conducted a photometric study of late-type members of the TW Hydrae association (TWA) and measured the rotation periods for 16 stars in 12 systems. For TWA stars listed by Webb et al. and Sterzik et al. (TWA 1-13 led by TW Hya = TWA 1) we find a median period of 4.7 d. However, for stars that we measured in the TWA 14-19 group identified b…
Energy deposition of pickup ions and heating of Titan's atmosphere
Johnson, R. E.; Michael, M.
The deposition of energy, escape of atomic and molecular nitrogen and heating of the upper atmosphere of Titan are studied using a Direct Simulation Monte Carlo method. It is found that the globally averaged flux of deflected magnetospheric atomic nitrogen ions and molecular pickup ions deposit more energy in Titan's upper atmosphere than solar ra…
Ring Analysis of Solar Subsurface Flows and Their Relation to Surface Magnetic Activity
Howe, R.; Komm, R.; Hill, F. +3 more
We measure the horizontal flows in the outer 2% of the Sun by analyzing 14 consecutive Carrington rotations of Global Oscillation Network Group (GONG) Doppler images and two of Michelson Doppler Imager (MDI) Dynamics Program data with the ring-diagram technique. The zonal and meridional flows show no variation with activity at low to medium activi…
A High Angular Resolution Search for the Progenitor of the Type Ic Supernova 2004gt
Cenko, S. B.; Kulkarni, S. R.; Matthews, K. +6 more
We report the results of a high spatial resolution search for the progenitor of Type Ic supernova SN 2004gt, using the newly commissioned Keck laser guide star adaptive optics (LGSAO) system along with archival Hubble Space Telescope data. This is the deepest search yet performed for the progenitor of any Type Ib/c event in a wide wavelength range…
Magnetic Fields from SOHO MDI Converted to the Mount Wilson 150 Foot Solar Tower Scale
Ulrich, Roger K.; Tran, Tham; Bertello, Luca +1 more
In order to permit the construction of long-duration time series dependent on the Sun's magnetic field, this paper presents a detailed cross-correlation between sets of simultaneous magnetograms from the Mount Wilson Observatory (MWO) and the Michelson Doppler Imager (MDI) aboard the SOHO spacecraft. The MWO 150 foot (45.72 m) solar tower telescop…
A Chandra X-ray survey of nearby dwarf starburst galaxies - I. Data reduction and results
Ott, Jürgen; Walter, Fabian; Brinks, Elias
We present an analysis of Chandra X-ray observations of a sample of eight dwarf starburst galaxies (IZw18, VIIZw403, NGC1569, NGC3077, NGC4214, NGC4449, NGC5253 and He2-10). Extended, diffuse X-ray emission is detected in all but two of the objects. Unresolved sources were found within all dwarf galaxies (total: 55 sources). These point sources ar…
The evolution of actively star-forming galaxies in the mid-infrared
Panuzzo, P.; Bressan, A.; Chavez, M. +3 more
In this paper we analyze the evolution of actively star-forming galaxies in the mid-infrared (MIR). This spectral region, characterized by continuum emission by hot dust and by the presence of strong emission features generally ascribed to polycyclic aromatic hydrocarbon (PAH) molecules, is the most strongly affected by the heating processes assoc…
A Hubble Space Telescope Search for Substellar Companions in the Young Cluster IC 348
Luhman, K. L.; McLeod, K. K.; Goldenson, N.
We present the results of a search for substellar companions to members of the star-forming cluster IC 348. Using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope, we have obtained deep, high-resolution images of the cluster through the F791W and F850LP filters. These data encompass 150 known members of IC 348, including 14 pr…
The 1-50 keV spectral and timing analysis of IGR J18027-2016: an eclipsing, high mass X-ray binary
Hill, A. B.; Knigge, C.; Walter, R. +9 more
We report the association of the INTEGRAL source IGR J18027-2016 with the BeppoSAX source SAX J1802.7-2017. IGR J18027-2016 is seen to be a weak, persistent source by the IBIS/ISGRI instrument on board INTEGRAL with an average source count rate of 0.58 counts s-1 ( 6.4 mCrab) in the 20-40 keV band. Timing analysis performed on the ISGRI…