Search Publications
Spectral and Timing Properties of the Magnetar CXOU J164710.2-455216
An, Hongjun; Kaspi, Victoria M.; Archibald, Robert +1 more
We report on spectral and timing properties of the magnetar CXOU J164710.2-455216 in the massive star cluster Westerlund 1. Using 11 archival observations obtained with Chandra and XMM-Newton over approximately 1000 days after the source's 2006 outburst, we study the flux and spectral evolution of the source. We show that the hardness of the sourc…
The imprint of the crustal magnetic field on the thermal spectra and pulse profiles of isolated neutron stars
Rea, Nanda; Viganò, Daniele; Perna, Rosalba +1 more
Isolated neutron stars (NSs) show a bewildering variety of astrophysical manifestations, presumably shaped by the magnetic field strength and topology at birth. Here, using state-of-the-art calculations of the coupled magnetic and thermal evolution of NSs, we compute the thermal spectra and pulse profiles expected for a variety of initial magnetic…
Hubble Space Telescope Fine Guidance Sensor Parallaxes for Four Classical Novae
Harrison, Thomas E.; Benedict, G. Fritz; McArthur, Barbara E. +1 more
We have used data obtained with the Fine Guidance Sensors on the Hubble Space Telescope to derive precise astrometric parallaxes for four classical novae: V603 Aql, DQ Her, GK Per, and RR Pic. All four objects exceeded the Eddington limit at visual maximum. Re-examination of the original light curve data for V603 Aql and GK Per has led us to concl…
A Study of Fast Flareless Coronal Mass Ejections
Chen, Y.; Song, H. Q.; Zhang, J. +5 more
Two major processes have been proposed to convert coronal magnetic energy into the kinetic energy of a coronal mass ejection (CME): resistive magnetic reconnection and the ideal macroscopic magnetohydrodynamic instability of a magnetic flux rope. However, it remains elusive whether both processes play a comparable role or one of them prevails duri…
Clusters of galaxies and variation of the fine structure constant
Galli, Silvia
We propose a new method to probe for variations in the fine structure constant α using clusters of galaxies, opening up a window on a new redshift range for such constraints. Hot clusters shine in the x-ray mainly due to bremsstrahlung, while they leave an imprint on the cosmic microwave background (CMB) frequency spectrum through the Sunyaev-Zel’…
Kelvin-Helmholtz Instability of a Coronal Streamer
Feng, L.; Inhester, B.; Gan, W. Q.
Shear-flow-driven instability can play an important role in energy transfer processes in coronal plasma. We present for the first time the observation of a kink-like oscillation of a streamer that is probably caused by the streaming kink-mode Kelvin-Helmholtz instability (KHI). The wave-like behavior of the streamer was observed by the Large Angle…
Dust, ice and gas in time (DIGIT): Herschel and Spitzer spectro-imaging of SMM3 and SMM4 in Serpens
van Dishoeck, E. F.; Evans, N. J.; Kristensen, L. E. +5 more
Context. Mid- and far-infrared observations of the environment around embedded protostars reveal a plethora of high excitation molecular and atomic emission lines. Different mechanisms for the origin of these lines have been proposed, including shocks induced by protostellar jets and radiation or heating by the embedded protostar of its immediate …
XMM-Newton observations of the Galactic Centre Region - I. The distribution of low-luminosity X-ray sources
Warwick, R. S.; Heard, V.
We exploit XMM-Newton archival data in a study of the extended X-ray emission emanating from Galactic Centre (GC) region. XMM-Newton EPIC-pn and EPIC-MOS observations, with a total exposure time approaching 0.5 and 1 Ms, respectively, were used to create mosaicked images of a 100 pc × 100 pc region centred on Sgr A* in four bands covering the 2-10…
Results from HOPS: A multiwavelength census of Orion protostars
Megeath, S. T.; Osorio, M.; Stanke, T. +7 more
Surveys with the Spitzer and Herschel space observatories are now enabling the discovery and characterization of large samples of protostars in nearby molecular clouds, providing the observational basis for a detailed understanding of star formation in diverse environments. We are pursuing this goal with the Herschel Orion Protostar Survey (HOPS),…
A chaotic long-lived vortex at the southern pole of Venus
Hueso, R.; Sánchez-Lavega, A.; Drossart, P. +3 more
Polar vortices are common in the atmospheres of rapidly rotating planets. On Earth and Mars, vortices are generated by surface temperature gradients and their strength is modulated by the seasonal insolation cycle. Slowly rotating Venus lacks pronounced seasonal forcing, but vortices are known to occur at both poles, in an atmosphere that rotates …