Search Publications
Active region upflows. I. Multi-instrument observations
Doyle, J. G.; Madjarska, M. S.; Huang, Z. +2 more
Context. We study upflows at the edges of active regions, called AR outflows, using multi-instrument observations.
Aims: This study intends to provide the first direct observational evidence of whether chromospheric jets play an important role in furnishing mass that could sustain coronal upflows. The evolution of the photospheric magnetic fi…
Far-infrared excess emission as a tracer of disk-halo interaction
Boulanger, F.; Lagache, G.; Kerp, J. +3 more
Context. Given the current and past star-formation in the Milky Way in combination with the limited gas supply, the re-fuelling of the reservoir of cool gas is an important aspect of Galactic astrophysics. The infall of H i halo clouds can, among other mechanisms, contribute to solving this problem.
Aims: We study the intermediate-velocity cl…
The EUV spectrum of the Sun: SOHO, SEM, and CDS irradiances
Andretta, V.; Del Zanna, G.; Didkovsky, L. +1 more
We use calibrated extreme-UV (EUV) spectral irradiances obtained from observations with the Solar & Heliospheric Observatory (SOHO) Coronal Diagnostics Spectrometer Normal Incidence Spectrometer (NIS) to estimate the signal measured by the Solar EUV Monitor (SEM) first-order band, 260 to 340 Å (SEM 1). The NIS observes the resonance lines He i…
Heating and cooling of the neutral ISM in the NGC 4736 circumnuclear ring
Armus, L.; Smith, J. D.; Draine, B. T. +12 more
The manner in which gas accretes and orbits within circumnuclear rings has direct implications for the star formation process. In particular, gas may be compressed and shocked at the inflow points, resulting in bursts of star formation at these locations. Afterwards the gas and young stars move together through the ring. In addition, star formatio…
Kinematic and thermal structure at the onset of high-mass star formation
Henning, Th.; Krause, O.; Beuther, H. +6 more
Context. Even though high-mass stars are crucial for understanding a diversity of processes within our galaxy and beyond, their formation and initial conditions are still poorly constrained.
Aims: We want to understand the kinematic and thermal properties of young massive gas clumps prior to and at the earliest evolutionary stages of high-mas…
Follow-up observations of X-ray emitting hot subdwarf stars: the He-rich sdO BD +37° 1977
Tiengo, A.; Mereghetti, S.; Esposito, P. +2 more
We report on the results of the first XMM-Newton satellite observation of the luminous and helium-rich O-type subdwarf BD +37° 1977 carried out in April 2014. X-ray emission is detected with a flux of about 4 × 10-14 erg cm-2 s-1 (0.2-1.5 keV), corresponding to a fX/fbol ratio ~ 10-7
Which fundamental constants for cosmic microwave background and baryon-acoustic oscillation?
Rich, James
We use the three-scale framework of Hu et al. to show how the cosmic microwave background (CMB) anisotropy spectrum depends on the fundamental constants. As expected, the spectrum depends only on dimensionless combinations of the constants, and we emphasize the points that make this generally true for cosmological observables. Our analysis suggest…
AGN torus emission for a homogeneous sample of bright flat-spectrum radio quasars
Castignani, G.; De Zotti, G.
We have selected a complete sample of 80 flat-spectrum radio quasars (FSRQs) from the Wilkinson Microwave Anisotropy Probe (WMAP) seven-year catalog within the Sloan Digital Sky Survey (SDSS) area, all with measured redshift, and have inspected their spectral energy distributions (SEDs) looking for evidence of an active galactic nucleus torus emis…
Testing for foreground residuals in the Planck foreground cleaned maps: A new method for designing confidence masks
Hansen, F. K.; Axelsson, M.; Ihle, H. T. +1 more
We test for foreground residuals in the foreground-cleaned Planck cosmic microwave background (CMB) maps outside and inside the U73 mask commonly used for cosmological analysis. The aim of this paper is to introduce a new method of validating masks by looking at the differences in cleaned maps obtained by different component-separation methods. By…
Variability of the soft X-ray excess in IRAS 13224-3809
Papadakis, I. E.; Kammoun, E. S.; Sabra, B. M.
We study the soft excess variability of the narrow line Seyfert 1 galaxy IRAS 13224-3809. We considered all five archival XMM-Newton observations, and we applied the flux-flux plot (FFP) method. We found that the FFPs were highly affected by the choice of the light curves' time bin size, most probably because of the fast and large amplitude variat…