Search Publications
Infrared and sub-mm observations of outbursting young stars with Herschel and Spitzer
Rab, C.; Audard, M.; Güdel, M. +3 more
Context. Episodic accretion plays an important role in the evolution of young stars. Although it has been under investigation for a long time, the origin of such episodic accretion events is not yet understood.
Aims: We investigate the dust and gas emission of a sample of young outbursting sources in the infrared to get a better understanding…
Envelopes and vertical amplitudes of disc-crossing orbits
Vieira, Ronaldo S. S.; Ramos-Caro, Javier
We recently found that regular orbits in axially symmetric galactic discs have their envelopes Z(R) accurately described by the relation Z(R)∝[ΣI(R)]-1/3, if their amplitudes are comparable to the disc thickness, where ΣI is the surface density of the disc (integrated over its whole vertical range). Moreover, the u…
Magnetic fields and extraordinarily bright radio emission in the X-ray faint galaxy group MRC 0116 + 111
Böhringer, H.; Simionescu, A.; Mernier, F. +4 more
MRC 0116 + 111 is a nearby (z = 0.132) poor galaxy group, which was previously known for exhibiting a bright diffuse radio emission with no central point-like source, presumably related to a past activity of the active galactic nucleus (AGN) in its central cD galaxy. Here, we present an X-ray observation (∼30 ks of cleaned XMM-Newton/EPIC exposure…
Enhanced Ionization in Magnetic Anomaly Regions of the Martian Lower Ionosphere Associated With Dust Storms
Haider, S. A.; Venkateswara Rao, N.; Leelavathi, V. +2 more
The Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express spacecraft observes vertical echoes from the normal ionosphere and oblique echoes from ionization bulges. The peak frequencies of these two kinds of echoes are, in general, nearly equal. In the present study, we report the detection of oblique echoes…
Development of Hydrogen and Helium Proximity Zones around Quasars
Zheng, Wei; Meiksin, Avery; Syphers, David
Increasing evidence suggests that He II proximity profiles in the quasar spectra at z ∼ 3-4 are sensitive probes of quasar ages. But the development of their H I counterparts is difficult to trace and remains poorly constrained. We compare the UV spectra of 15 He II quasars with their high-resolution optical counterparts and find a significant cor…
Gravitational Lens System PS J0147+4630 (Andromeda’s Parachute): Main Lensing Galaxy and Optical Variability of the Quasar Images
Goicoechea, Luis J.; Shalyapin, Vyacheslav N.
Because follow-up observations of quadruple gravitational lens systems are of extraordinary importance for astrophysics and cosmology, we present single-epoch optical spectra and r-band light curves of PS J0147+4630. This recently discovered system mainly consists of four images ABCD of a background quasar around a foreground galaxy G that acts as…
Two merging galaxy clusters with very hot shock fronts observed shortly before pericentric passage
Lopes, P. A. A.; Laganá, T. F.; Machado, R. E. G. +2 more
We present a detailed analysis of two merging clusters, from XMM-Newton X-ray archival data: PLCKESZ G036.7+14.9 (z = 0.15; hereafter G036) and PLCK G292.5+22.0 (z = 0.30; hereafter G292). We notice that the intracluster medium (ICM) is heated as a result of the merger, and we find evidence for a merger shock in the region between both subcluster …
Unveiling the enigma of ATLAS17aeu
Covino, S.; D'Avanzo, P.; Campana, S. +42 more
Aims: The unusual transient ATLAS17aeu was serendipitously detected within the sky localisation of the gravitational wave trigger GW 170104. The importance of a possible association with gravitational waves coming from a binary black hole merger led to an extensive follow-up campaign, with the aim of assessing a possible connection with GW 17…
Automatic endmember bundle unmixing methodology for lunar regional area mineral mapping
Yin, Jihao; Huang, Chenyu; Luo, Xiaoyan +1 more
The mineral distribution on lunar surface can contribute to studying lunar evolution, while abundance quantification is still challenging. Unmixing on spectral reflectance data is an effective way for mineral resource explanation, especially in hardly accessible area. In regional area unmixing, some existing unmixing models mainly rely on spectral…
Observations of Red Giants with Suspected Massive Companions
Tokovinin, Andrei; Makarov, Valeri V.
Motivated by the existence of binary systems where a stellar-mass black hole is bound to a normal star, we selected four red giants with large radial velocity (RV) variation from the survey of Space Interferometry Mission (SIM) grid stars and monitored their RVs for several months. None turned out to contain a massive companion above 2.5 solar mas…