Search Publications
Discovery of the first Earth-sized planets orbiting a star other than our Sun in the Kepler-20 system
Torres, Guillermo; Fressin, François
Discovering other worlds the size of our own has been a long-held dream of astronomers. The transiting planets Kepler-20 e and Kepler-20 f, which belong to a multi-planet system, hold a very special place among the many groundbreaking discoveries of the Kepler mission because they finally realized that dream. The radius of Kepler-20 f is essential…
High energy polarimetry of prompt GRB emission
McConnell, Mark L.
[Evidence] of polarized γ-ray emission (> 50 keV) from Gamma-Ray Bursts (GRBs) has been accumulated in recent years. Measurements have been reported with levels in the range of 30-80%, typically with limited statistical significance. No clear picture has yet emerged with regards to the polarization properties of GRBs. Taken at face value, the d…
Circumstellar debris and pollution at white dwarf stars
Farihi, J.
Circumstellar disks of planetary debris are now known or suspected to closely orbit hundreds of white dwarf stars. To date, both data and theory support disks that are entirely contained within the preceding giant stellar radii, and hence must have been produced during the white dwarf phase. This picture is strengthened by the signature of materia…
Empirical tests of pre-main-sequence stellar evolution models with eclipsing binaries
Torres, Guillermo; Stassun, Keivan G.; Feiden, Gregory A.
We examine the performance of standard pre-main-sequence (PMS) stellar evolution models against the accurately measured properties of a benchmark sample of 26 PMS stars in 13 eclipsing binary (EB) systems having masses 0.04-4.0 M⊙ and nominal ages ≈1-20 Myr. We provide a definitive compilation of all fundamental properties for the EBs, …
The first extrasolar planet detected via gravitational microlensing
Bond, Ian A.
In gravitational microlensing, distant planetary systems may be discovered by utilizing them as naturally occuring lenses. Efforts to find planets by this technique began in the 1990s. The first definitive detection of an extrasolar planet by microlensing was made in 2003 in the event OGLE 2003-BLG-235/MOA 2003-BLG-53, where the observed light cur…
The environments of short-duration gamma-ray bursts and implications for their progenitors
Berger, Edo
The study of short-duration gamma-ray bursts (GRBs) experienced a complete revolution in recent years thanks to the discovery of the first afterglows and host galaxies starting in May 2005. These observations demonstrated that short GRBs are cosmological in origin, reside in both star forming and elliptical galaxies, are not associated with supern…
New views on the emission and structure of the solar transition region
He, Jiansen; Tian, Hui; Marsch, Eckart +2 more
The Sun is the only star that we can spatially resolve and it can be regarded as a fundamental plasma laboratory of astrophysics. The solar transition region (TR), the layer between the solar chromosphere and corona, plays an important role in solar wind origin and coronal heating. Recent high-resolution observations made by SOHO, TRACE, and Hinod…
Supersoft X-ray sources: Confronting the van den Heuvel paradigm
Charles, P. A.; Heathcote, B.; McGowan, K. E. +3 more
The origin of the extremely soft (low temperature) X-rays produced in the supersoft X-ray sources (or SSS) has been a subject of debate for much of the 25 years since their discovery. The currently accepted paradigm is that they are Eddington-limited accreting white dwarfs in which the accreted material is undergoing steady nuclear burning, thereb…
High velocity outflows in narrow absorption line quasars
Chartas, G.; Giustini, M.; Charlton, J. +6 more
The current paradigm for the AGN phenomenon is a central engine that consists of an inflow of material accreting in the form of a disk onto a supermassive black hole. Observations in the UV and optical find high velocity ionized material outflowing from the black hole. We present results from Suzaku and XMM-Newton observations of a sample of intri…
Kinematics of the broad absorption line region in QSOs: Rotation and random motion
Popović, L. Č.; Antoniou, A.; Danezis, E. +2 more
Assuming that the Broad Absorption Line Region - BALR (originated in a disk wind) is composed of a number of successive independent absorbing density layers, which have apparent rotational and radial velocities and where ions have random velocities, we applied a model in order to obtain the kinematical parameters of BALR, by fitting the broad abso…