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Reconstruction of solar irradiance variations in cycles 21-23 based on surface magnetic fields
Solanki, S. K.; Krivova, N. A.; Fröhlich, C. +1 more
Aims.We present a reconstruction of total solar irradiance (TSI) back to 1974, i.e. from the minimum of cycle 21 to the declining phase of cycle 23. We also present a cross-calibration between the magnetograms obtained by the 512 channel magnetograph and the spectromagnetograph at Kitt Peak.
Methods: .The TSI reconstruction is carried out usin…
The Arches Cluster Mass Function
Najarro, F.; Figer, Donald F.; Kim, Sungsoo S. +1 more
We have analyzed H- and Ks-band images of the Arches cluster obtained using the NIRC2 instrument on Keck with the laser guide star adaptive optics (LGS AO) system. With the help of the LGS AO system, we were able to obtain the deepest ever photometry for this cluster and its neighborhood and derive the background-subtracted present-day …
A Survey of Galaxy Kinematics to z~1 in the TKRS/GOODS-N Field. II. Evolution in the Tully-Fisher Relation
Weiner, Benjamin J.; Faber, S. M.; Willmer, Christopher N. A. +7 more
We use kinematic measurements of a large sample of galaxies from the Team Keck Redshift Survey in the GOODS-N field to measure evolution in the optical and near-IR Tully-Fisher (TF) relations to z=1.2. We construct TF relations with integrated line-of-sight velocity widths of ~1000 galaxies in B and ~670 in J; these relations have large scatter, a…
Motion of observed structures calculated from multi-point magnetic field measurements: Application to Cluster
Balogh, A.; Zong, Q. -G.; Lucek, E. +5 more
A new method is described which calculates the velocity of observed, quasi-stationary structures at every moment in time from multi-point magnetic field measurements. Once the magnetic gradient tensor G = $\nabla$$\vec {B and the time variation of the magnetic field have been estimated at every moment, the velocity can then be determined, in princ…
Solar Sources of Impulsive Solar Energetic Particle Events and Their Magnetic Field Connection to the Earth
Liu, Yang; Yashiro, Seiji; Nitta, Nariaki V. +3 more
This paper investigates the solar origin of impulsive solar energetic particle (SEP) events, often referred to as 3He-rich flares, by attempting to locate the source regions of 117 events as observed at ~2-3 MeV amu-1. Given large uncertainties as to when ions at these energies were injected, we use type III radio bursts that…
Detection of Wolf-Rayet stars in host galaxies of gamma-ray bursts (GRBs): are GRBs produced by runaway massive stars ejected from high stellar density regions?
Le Floc'h, E.; Schaerer, D.; Dessauges-Zavadsky, M. +3 more
We have obtained deep spectroscopic observations of several nearby gamma-ray burst (GRB) host galaxies revealing for the first time the presence of Wolf-Rayet (WR) stars and numerous O stars located in rich and compact clusters or star forming regions. Surprisingly, high spatial resolution imaging shows that the GRBs and the associated supernovae …
Subvisible CO 2 ice clouds detected in the mesosphere of Mars
Montmessin, Franck; Bertaux, Jean-Loup; Perrier, Séverine +8 more
The formation of CO 2 ice clouds in the upper atmosphere of Mars has been suggested in the past on the basis of a few temperature profiles exhibiting portions colder than CO 2 frost point. However, the corresponding clouds were never observed. In this paper, we discuss the detection of the highest clouds ever observed on Mars…
Identification of the OGLE-2003-BLG-235/MOA-2003-BLG-53 Planetary Host Star
Anderson, Jay; Udalski, Andrzej; Gould, Andrew +2 more
We present the results of HST observations of the host star for the first definitive extrasolar planet detected by microlensing. The light-curve model for this event predicts that the lens star should be separated from the source star by ~6 mas at the time of the HST images. If the lens star is a late G, K, or early M dwarf, then it will be visibl…
Europa's atmosphere, gas tori, and magnetospheric implications
Smyth, William H.; Marconi, Max L.
A two-dimensional kinetic model calculation for the water group species (H 2O, H 2, O 2, OH, O, H) in Europa's atmosphere is undertaken to determine its basic compositional structure, gas escape rates, and velocity distribution information to initialize neutral cloud model calculations for the most important gas to…
Multivariate analysis of globular cluster horizontal branch morphology: searching for the second parameter
Djorgovski, S. G.; Recio-Blanco, A.; Piotto, G. +2 more
Aims.The interpretation of globular cluster horizontal branch (HB) morphology is a classical problem that can significantly blur our understanding of stellar populations.
Methods: .We present a new multivariate analysis connecting the effective temperature extent of the HB with other cluster parameters. The work is based on Hubble Space Telesc…