Search Publications
H-ATLAS: estimating redshifts of Herschel sources from sub-mm fluxes
Valtchanov, I.; Ivison, R. J.; Scott, D. +29 more
Upon its completion, the Herschel Astrophysics Terahertz Large Area Survey (H-ATLAS) will be the largest sub-millimetre survey to date, detecting close to half-a-million sources. It will only be possible to measure spectroscopic redshifts for a small fraction of these sources. However, if the rest-frame spectral energy distribution (SED) of a typi…
In Situ Measurements of the Size and Density of Titan Aerosol Analogs
Hörst, S. M.; Tolbert, M. A.
The organic haze produced from complex CH4/N2 chemistry in the atmosphere of Titan plays an important role in processes that occur in the atmosphere and on its surface. The haze particles act as condensation nuclei and are therefore involved in Titan's methane hydrological cycle. They also may behave like sediment on Titan's …
Luminous and Variable Stars in M31 and M33. I. The Warm Hypergiants and Post-red Supergiant Evolution
Humphreys, Roberta M.; Davidson, Kris; Martin, John C. +4 more
The progenitors of Type IIP supernovae (SNe) have an apparent upper limit to their initial masses of about 20 M ⊙, suggesting that the most massive red supergiants evolve to warmer temperatures before their terminal explosion. But very few post-red supergiants are known. We have identified a small group of luminous stars in M31 and M33 …
Intense current sheets in the magnetotail: Peculiarities of electron physics
Petrukovich, A. A.; Zelenyi, L. M.; Nakamura, R. +2 more
In this paper we investigate intense (with current density larger than 15 nA/m2) thin (thickness is less than proton gyroradius) horizontal current sheets observed by Cluster in 2003 year in the Earth magnetotail. We compare observed profiles of the curlometer current density with particle currents and analytical estimates. We show that…
Measuring Galaxy Star Formation Rates from Integrated Photometry: Insights from Color-Magnitude Diagrams of Resolved Stars
Dolphin, Andrew E.; Skillman, Evan D.; Williams, Benjamin F. +9 more
We use empirical star formation histories (SFHs), measured from Hubble-Space-Telescope-based resolved star color-magnitude diagrams, as input into population synthesis codes to model the broadband spectral energy distributions (SEDs) of 50 nearby dwarf galaxies (6.5 < log M */M ⊙ < 8.5, with metallicities ~10% solar). I…
Polarimetry and the High-energy Emission Mechanisms in Quasar Jets: The Case of PKS 1136-135
Baum, Stefi A.; O'Dea, Christopher P.; Perlman, Eric S. +11 more
Since the discovery of kiloparsec-scale X-ray emission from quasar jets, the physical processes responsible for their high-energy emission have been poorly defined. A number of mechanisms are under active debate, including synchrotron radiation, inverse-Comptonized cosmic microwave background (IC/CMB) emission, and other Comptonization processes. …
A Highly Elongated Prominent Lens at z = 0.87: First Strong-lensing Analysis of El Gordo
Hughes, John P.; Barrientos, L. Felipe; Mandelbaum, Rachel +4 more
We present the first strong-lensing (SL) analysis of the galaxy cluster ACT-CL J0102-4915 (El Gordo), in recent HST/ACS images, revealing a prominent strong lens at a redshift of z = 0.87. This finding adds to the already-established unique properties of El Gordo: it is the most massive, hot, X-ray luminous, and bright Sunyaev-Zeldovich effect clu…
PROBA2: Mission and Spacecraft Overview
Zender, J.; Schwehm, G.; de Groof, A. +9 more
Within the European Space Agency's (ESA) General Support and Technology Programme (GSTP), the Project for On-Board Autonomy (PROBA) missions provide a platform for in-orbit technology demonstration. Besides the technology demonstration goal, the satellites allow to provide services to, e.g., scientific communities. PROBA1 has been providing multi-…
Pathways of Large-scale Magnetic Couplings between Solar Coronal Events
DeRosa, Marc L.; Title, Alan M.; Schrijver, Carolus J. +1 more
The high-cadence, comprehensive view of the solar corona by SDO/AIA shows many events that are widely separated in space while occurring close together in time. In some cases, sets of coronal events are evidently causally related, while in many other instances indirect evidence can be found. We present case studies to highlight a variety of coupli…
Space Velocities of Southern Globular Clusters. VII. NGC 6397, NGC 6626 (M28), and NGC 6656 (M22)
Casetti-Dinescu, Dana I.; Girard, Terrence M.; van Altena, William F. +3 more
We have measured the absolute proper motions of globular clusters NGC 6397, NGC 6626 (M22), and NGC 6656 (M28) as part of our ongoing Southern Proper-Motion Program. The reference system is the ICRS via Hipparcos stars for these three low-Galactic-latitude clusters. Formal errors range between ~0.3 and 0.7 mas yr-1. Notable is the resul…