Search Publications
Optical observations of comet 67P/Churyumov-Gerasimenko with the Nordic Optical Telescope. Comet activity before the solar conjunction
Snodgrass, C.; Schulz, R.; Nilsson, K. +4 more
Context. 67P/Churyumov-Gerasimenko (67P) is a short-period Jupiter-family comet that was chosen as a target for the Rosetta mission by the European Space Agency (ESA). Monitoring of 67P with the Nordic Optical Telescope (NOT; La Palma, Spain) intends to aid this mission by providing ground-based reference information about the overall activity of …
A spatial-correlation analysis of the cubic 3-torus topology based on the Planck 2013 data
Aurich, R.
Spatial correlations of the cubic 3-torus topology are analysed using the Planck 2013 data. The spatial-correlation method for detecting multiply connected spaces is based on the fact that positions on the cosmic microwave background (CMB) sky, that are separated by large angular distances, can be spatially much nearer according to a hypothesized …
Cycle Length Dependence of Stellar Magnetic Activity and Solar Cycle 23
Lee, Jeongwoo; Choi, Hwajin; Oh, Suyeon +3 more
Solar cycle (SC) 23 was extraordinarily long with remarkably low magnetic activity. We have investigated whether this is a common behavior of solar-type stars. From the Ca ii H and K line intensities of 111 stars observed at Mount Wilson Observatory from 1966 to 1991, we have retrieved data of all 23 G-type stars and recalculated their cycle lengt…
Observations of Galactic star-forming regions with the Cosmic Background Imager at 31 GHz
Dickinson, C.; Pearson, T. J.; Readhead, A. C. S. +6 more
Studies of the diffuse Galactic radio emission are interesting both for better understanding the physical conditions in our Galaxy and for minimizing the contamination in cosmological measurements. Motivated by this, we present Cosmic Background Imager 31 GHz observations of the Galactic regions NGC 6357, NGC 6334, W51 and W40 at ∼4.5 arcmin resol…
Modelling warm absorption in HST/COS spectrum of Mrk 290 with XSTAR
Kriss, G. A.; Kallman, T. R.; Zhang, S. N. +4 more
We present a new method to model an HST/COS (Hubble Space Telescope/Cosmic Origins Spectrograph) spectrum, aimed to analyse intrinsic UV absorption from the outflow of Mrk 290, a Seyfert I galaxy. We use newly updated XSTAR to generate photoionization models for the intrinsic absorption from the active galactic nuclei (AGN) outflow, the line emiss…
Evolution of solar active regions: Detecting the emergence of new magnetic field through multifractal segmentation
Golovko, A. A.; Salakhutdinova, I. I.
New emerging magnetic flux is identifed using a multifractal segmentation method used to investigate regularities in the evolution of active regions and activity complexes. The SOLIS, MDI SOHO, and SOT Hinode magnetograms were used. Observations of the active region NOAA 10488 on October 26-28, 2003 indicate considerable variability of areas of ne…
Infrared-faint radio sources remain undetected at far-infrared wavelengths. Deep photometric observations using the Herschel Space Observatory
Norris, R. P.; Leipski, C.; Spitler, L. R. +3 more
Context. Showing 1.4 GHz flux densities in the range of a few to a few tens of mJy, infrared-faint radio sources (IFRS) are a type of galaxy characterised by faint or absent near-infrared counterparts and consequently extreme radio-to-infrared flux density ratios up to several thousand. Recent studies showed that IFRS are radio-loud active galacti…
SOFIA/FORCAST Observations of Warm Dust in S106: A Fragmented Environment
Hill, T.; Smith, N.; Fazio, G. G. +22 more
We present mid-IR (19-37 µm) imaging observations of S106 from SOFIA/FORCAST, complemented with IR observations from Spitzer/IRAC (3.6-8.0 µm), IRTF/MIRLIN (11.3 and 12.5 µm), and Herschel/PACS (70 and 160 µm). We use these observations, observations in the literature, and radiation transfer modeling to study the heating an…
Self-consistent Orbits and Physical Properties for Eight Single-lined Spectroscopic Binaries
Wang, Xiaoli; Ren, Shulin; Fu, Yanning
For single-lined spectroscopic binaries (SB1s), self-consistent orbits can be determined via a simultaneous fit including both radial velocity data and the Hipparcos Intermediate Astrometric Data. Using the ratio λ of the semimajor axes of the photocenter to the primary orbits, the present paper develops an iterative fitting method. First, an init…
Modeling the Power Spectra of Active Galactic Nuclei with Markov Chain Monte Carlo
Marshall, Kevin
We present a new method for calculating the power spectral density (PSD) of a light curve using Markov Chain Monte Carlo principles. This method allows for a faster estimation of PSD parameters, along with more robust estimates of the uncertainties for each parameter. We show that this technique is valid by applying it to a simulated light curve, …