Search Publications
Kinematics of interacting CMEs of 25 and 28 September 2012
Srivastava, Nandita; Mishra, Wageesh; Singh, Talwinder
We have studied two coronal mass ejections (CMEs) that occurred on 25 and 28 September 2012 and interacted near the Earth. By fitting the Graduated Cylindrical Shell model on the SECCHI/COR2 images and applying the Stereoscopic Self-Similar Expansion method on the SECCHI/HI images, the initial direction of both the CMEs is estimated to be west of …
Investigating powerful jets in radio-loud narrow-line Seyfert 1s
Larsson, J.; Giroletti, M.; Dallacasa, D. +5 more
We report results on multiband observations from radio to γ-rays of the two radio-loud narrow-line Seyfert 1 (NLSy1) galaxies PKS 2004-447 and J1548+3511. Both sources show a core-jet structure on parsec scale, while they are unresolved at the arcsecond scale. The high core dominance and the high variability brightness temperature make these NLSy1…
The SCITEAS experiment: Optical characterizations of sublimating icy planetary analogues
Thomas, N.; El-Maarry, M. R.; Pommerol, A. +3 more
We have designed and built a laboratory facility to investigate the spectro-photometric and morphologic properties of different types of ice-bearing planetary surface analogs and follow their evolution upon exposure to a low pressure and low temperature environment. The results obtained with this experiment are used to verify and improve our inter…
Venus mesospheric sulfur dioxide measurement retrieved from SOIR on board Venus Express
Vandaele, A. C.; Robert, S.; Wilquet, V. +5 more
SOIR on board Venus Express sounds the Venus upper atmosphere using the solar occultation technique. It detects the signature from many Venus atmosphere species, including those of SO2 and CO2. SO2 has a weak absorption structure at 4 µm, from which number density profiles are regularly inferred. SO2
Study of the reflection spectrum of the accreting neutron star GX 3+1 using XMM-Newton and INTEGRAL
Sanna, A.; Di Salvo, T.; Burderi, L. +6 more
Broad emission features of abundant chemical elements, such as iron, are commonly seen in the X-ray spectra of accreting compact objects and their studies can provide useful information about the geometry of the accretion processes. In this work, we focus our attention on GX 3+1, a bright, persistent accreting low-mass X-ray binary, classified as …
The Herschel Exploitation of Local Galaxy Andromeda (HELGA). VI. The Distribution and Properties of Molecular Cloud Associations in M31
Fritz, J.; Cooray, A.; Lebouteiller, V. +18 more
In this paper we present a catalog of giant molecular clouds (GMCs) in the Andromeda (M31) galaxy extracted from the Herschel Exploitation of Local Galaxy Andromeda (HELGA) data set. GMCs are identified from the Herschel maps using a hierarchical source extraction algorithm. We present the results of this new catalog and characterize the spatial d…
What powers the 3000-day light curve of SN 2006gy?
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Cenko, S. Bradley +11 more
SN 2006gy was the most luminous supernova (SN) ever observed at the time of its discovery and the first of the newly defined class of superluminous supernovae (SLSNe). The extraordinary energetics of SN 2006gy and all SLSNe (>1051 erg) require either atypically large explosion energies (e.g. pair-instability explosion) or the efficie…
Estimating the Height of CMEs Associated with a Major SEP Event at the Onset of the Metric Type II Radio Burst during Solar Cycles 23 and 24
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +2 more
We studied the coronal mass ejection (CME) height at the onset of 59 metric type II radio bursts associated with major solar energetic particle (SEP) events, excluding ground level enhancements (GLEs), during solar cycles 23 and 24. We calculated CME heights using a simple flare-onset method used by Gopalswamy et al. to estimate CME heights at the…
Deceleration of Alpha Particles in the Solar Wind by Instabilities and the Rotational Force: Implications for Heating, Azimuthal Flow, and the Parker Spiral Magnetic Field
Verscharen, Daniel; Hollweg, Joseph V.; Bourouaine, Sofiane +1 more
Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including relative drifts between particle species. Two non-collisional mechanisms have been proposed for limiting differential flow between alpha particles and protons: plasma instabilities and the rotational force. Bot…
Variable Reddening and Broad Absorption Lines in the Narrow-line Seyfert 1 Galaxy WPVS 007: An Origin in the Torus
Komossa, S.; Terndrup, Donald M.; Leighly, Karen M. +2 more
We report the discovery of an occultation event in the low-luminosity narrow-line Seyfert 1 galaxy WPVS 007 in 2015 February and March. In concert with longer timescale variability, these observations place strong constraints on the nature and location of the absorbing material. Swift monitoring has revealed a secular decrease since ∼2010 accompan…