Search Publications
Observations of the Coronal Mass Ejection with a Complex Acceleration Profile
Reva, A. A.; Kirichenko, A. S.; Ulyanov, A. S. +1 more
We study the coronal mass ejection (CME) with a complex acceleration profile. The event occurred on 2009 April 23. It had an impulsive acceleration phase, an impulsive deceleration phase, and a second impulsive acceleration phase. During its evolution, the CME showed signatures of different acceleration mechanisms: kink instability, prominence dra…
Studying the accretion geometry of EXO 2030+375 at luminosities close to the propeller regime
Wilms, J.; Pottschmidt, K.; Kretschmar, P. +10 more
The Be X-ray binary EXO 2030+375was in an extended low-luminosity state during most of 2016. We observed this state with NuSTARand Swift, supported by INTEGRALobservations and optical spectroscopy with the Nordic Optical Telescope (NOT). We present a comprehensive spectral and timing analysis of these data here to study the accretion geometry and …
The extremely metal-poor galaxy DDO 68: the luminous blue variable, Hα shells and the most luminous stars
Moiseev, A. V.; Makarova, L. N.; Makarov, D. I. +2 more
This paper presents new results from the ongoing study of the unusual Lynx-Cancer void galaxy DDO 68, which has star-forming regions of record low metallicity [12+log (O/H) ∼7.14]. The results include the following. (I) A new spectrum and photometry have been obtained with the 6-m SAO RAS telescope (BTA) for the luminous blue variable (LBV = DDO68…
Possible regular phenomena in EXO 2030+375
Makishima, Kazuo; Santangelo, Andrea; Moritani, Yuki +4 more
In the last 10 yr, since its last giant outburst in 2006, regular X-ray outbursts (type I) were detected every periastron passage in the Be X-ray binary EXO 2030+375. Recently, however, it was reported that the source started to show a peculiar behavior: its X-ray flux decreased significantly and type I outbursts were missed in several cases. At t…
The accretion environment of supergiant fast X-ray transients probed with XMM-Newton
Bernardini, F.; Romano, P.; Ferrigno, C. +3 more
Context. Supergiant fast X-ray (SFXT) transients are a peculiar class of supergiant X-ray binaries characterized by a remarkable variability in the X-ray domain, widely ascribed to accretion from a clumpy stellar wind.
Aims: In this paper we performed a systematic and homogeneous analysis of the sufficiently bright X-ray flares observed with …
Stepwise heating of lunar anorthosites 60025, 60215, 65315 possibly reveals an indigenous noble gas component on the Moon
Gudipati, Murthy S.; Avice, Guillaume; Henderson, Bryana +2 more
Despite extensive effort during the last four decades, no clear signature of a lunar indigenous noble gas component has been found. In order to further investigate the possible occurrence of indigenous volatiles in the Moon, we have re-analyzed the noble gas and nitrogen isotopic compositions in three anorthosite samples. Lunar anorthosites 60025,…
Investigating the X-ray counterparts to unidentified sources in the 1000-orbit INTEGRAL/IBIS catalogue
Bird, A. J.; Fiocchi, M.; Ubertini, P. +6 more
The latest INTEGRAL/IBIS all-sky survey lists 219 hard X-ray sources whose nature is still unknown. We report on our ongoing campaign aimed at identifying these high-energy emitters by exploiting the focusing capabilities of the X-ray Telescope (XRT, 0.2-10 keV) onboard Swift, which allow an enhancement of the source localization to arcsec level, …
The Prototypical Young L/T-Transition Dwarf HD 203030B Likely Has Planetary Mass
Metchev, Stanimir; Miles-Páez, Paulo A.; Marengo, Massimo +2 more
Upon its discovery in 2006, the young L7.5 companion to the solar analog HD 203030 was found to be ≈ 200 K cooler than older late-L dwarfs, which is quite unusual. HD 203030B offered the first clear indication that the effective temperature at the L-to-T spectral type transition depends on surface gravity: now a well-known characteristic of low-gr…
The Araucaria Project: The Distance to the Fornax Dwarf Galaxy from Near-infrared Photometry of RR Lyrae Stars
Gieren, Wolfgang; Pietrzyński, Grzegorz; Górski, Marek +2 more
We have obtained single-phase near-infrared (NIR) magnitudes in the J and K bands for 77 RR Lyrae (RRL) stars in the Fornax Dwarf Spheroidal Galaxy. We have used different theoretical and empirical NIR period-luminosity-metallicity calibrations for RRL stars to derive their absolute magnitudes, and found a true, reddening-corrected distance modulu…
Consistency of Hitomi, XMM-Newton, and Chandra 3.5 keV data from Perseus
Conlon, Joseph P.; Day, Francesca; Jennings, Nicholas +2 more
Hitomi observations of Perseus with the Soft X-ray Spectrometer (SXS) provide a high-resolution look at the 3.5 keV feature reported by multiple groups in the Perseus cluster. The Hitomi spectrum—which involves the sum of diffuse cluster emission and the pointlike central active galactic nucleus (AGN)—does not show any excess at E ∼3.5 keV , givin…