Search Publications

Comparison of Line-of-Sight Magnetograms Taken by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager and Solar and Heliospheric Observatory/Michelson Doppler Imager
DOI: 10.1007/s11207-012-9976-x Bibcode: 2012SoPh..279..295L

Liu, Y.; Sun, X.; Hoeksema, J. T. +7 more

We compare line-of-sight magnetograms from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) and the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO). The line-of-sight magnetic signal inferred from the calibrated MDI data is greater than that derived from the HMI data by a …

2012 Solar Physics
SOHO 243
Global model of lower band and upper band chorus from multiple satellite observations
DOI: 10.1029/2012JA017978 Bibcode: 2012JGRA..11710225M

Meredith, Nigel P.; Horne, Richard B.; Thorne, Richard M. +4 more

Gyroresonant wave particle interactions with whistler mode chorus play a fundamental role in the dynamics of the Earth's radiation belts and inner magnetosphere, affecting both the acceleration and loss of radiation belt electrons. Knowledge of the variability of chorus wave power as a function of both spatial location and geomagnetic activity, re…

2012 Journal of Geophysical Research (Space Physics)
Cluster DoubleStar 241
GOODS-Herschel: the far-infrared view of star formation in active galactic nucleus host galaxies since z ≈ 3
DOI: 10.1111/j.1365-2966.2011.19675.x Bibcode: 2012MNRAS.419...95M

Magnelli, B.; Lutz, D.; Altieri, B. +28 more

We present a study of the infrared properties of X-ray selected, moderate-luminosity (i.e. LX= 1042-1044 erg s-1) active galactic nuclei (AGNs) up to z ≈ 3, in order to explore the links between star formation in galaxies and accretion on to their central black holes. We use 100 and 160 µ m fluxes …

2012 Monthly Notices of the Royal Astronomical Society
Herschel eHST 239
Fundamental parameters and infrared excesses of Hipparcos stars
DOI: 10.1111/j.1365-2966.2012.21873.x Bibcode: 2012MNRAS.427..343M

Zijlstra, A. A.; Boyer, M. L.; McDonald, I.

We derive the fundamental parameters (temperature and luminosity) of 107 619 Hipparcos stars and place these stars on a true Hertzsprung-Russell diagram. This is achieved by comparing BT-SETTL model atmospheres to spectral energy distributions (SEDs) created from Hipparcos, Tycho, Sloan Digital Sky Survey, DENIS, Two Micron All Sky Survey, MSX, AK…

2012 Monthly Notices of the Royal Astronomical Society
AKARI Hipparcos 236
Rotational velocities of A-type stars. IV. Evolution of rotational velocities
DOI: 10.1051/0004-6361/201117691 Bibcode: 2012A&A...537A.120Z

Royer, F.; Zorec, J.

Context. In previous works of this series, we have shown that late B- and early A-type stars have genuine bimodal distributions of rotational velocities and that late A-type stars lack slow rotators. The distributions of the surface angular velocity ratio Ω/Ωcritcrit is the critical angular velocity) have peculiar shapes a…

2012 Astronomy and Astrophysics
Hipparcos 233
Water in star-forming regions with Herschel (WISH). II. Evolution of 557 GHz 110-101 emission in low-mass protostars
DOI: 10.1051/0004-6361/201118146 Bibcode: 2012A&A...542A...8K

Liseau, R.; van Dishoeck, E. F.; Bergin, E. A. +22 more

Context. Water is a key tracer of dynamics and chemistry in low-mass star-forming regions, but spectrally resolved observations have so far been limited in sensitivity and angular resolution, and only data from the brightest low-mass protostars have been published.
Aims: The first systematic survey of spectrally resolved water emission in 29 …

2012 Astronomy and Astrophysics
Herschel 232
The M31 Velocity Vector. II. Radial Orbit toward the Milky Way and Implied Local Group Mass
DOI: 10.1088/0004-637X/753/1/8 Bibcode: 2012ApJ...753....8V

Anderson, Jay; van der Marel, Roeland P.; Beaton, Rachael L. +5 more

We determine the velocity vector of M31 with respect to the Milky Way and use this to constrain the mass of the Local Group, based on Hubble Space Telescope proper-motion measurements of three fields presented in Paper I. We construct N-body models for M31 to correct the measurements for the contributions from stellar motions internal to M31. This…

2012 The Astrophysical Journal
eHST 231
On the Cluster Physics of Sunyaev-Zel'dovich and X-Ray Surveys. I. The Influence of Feedback, Non-thermal Pressure, and Cluster Shapes on Y-M Scaling Relations
DOI: 10.1088/0004-637X/758/2/74 Bibcode: 2012ApJ...758...74B

Bond, J. R.; Battaglia, N.; Sievers, J. L. +1 more

The utility of large Sunyaev-Zel'dovich (SZ) surveys for determining cosmological parameters from cluster abundances is limited by the theoretical uncertainties in the integrated SZ-flux-to-mass relation, Y-M. We explore how non-thermal pressure and the anisotropic shape of the gas distribution of the intracluster medium (ICM) impacts Y-M scaling …

2012 The Astrophysical Journal
Planck 231
The warm gas atmosphere of the HD 100546 disk seen by Herschel. Evidence of a gas-rich, carbon-poor atmosphere?
DOI: 10.1051/0004-6361/201118218 Bibcode: 2012A&A...541A..91B

van Dishoeck, E. F.; Bruderer, S.; Herczeg, G. J. +1 more

Context. With the Herschel Space Observatory, lines of simple molecules (C+, O, and high-J lines of CO, Jup ≳ 14) have been observed in the atmosphere of protoplanetary disks. When combined with ground-based data on [C i], all principle forms of carbon can be studied. These data allow us to test model predictions for the main…

2012 Astronomy and Astrophysics
Herschel IUE 229
Temporal variations in the evaporating atmosphere of the exoplanet HD 189733b
DOI: 10.1051/0004-6361/201219363 Bibcode: 2012A&A...543L...4L

Ehrenreich, D.; Lecavelier des Etangs, A.; Bourrier, V. +8 more

Atmospheric escape has been detected from the exoplanet HD 209458b through transit observations of the hydrogen Lyman-α line. Here we present spectrally resolved Lyman-α transit observations of the exoplanet HD 189733b at two different epochs. These HST/STIS observations show for the first time that there are …

2012 Astronomy and Astrophysics
eHST 229