Search Publications
Four-month chromospheric and coronal activity cycle in τ Boötis
Schmitt, J. H. M. M.; Robrade, J.; Schröder, K. -P. +3 more
We have used our robotic TIGRE facility to closely monitor the star τ Boo during the last three observing seasons 2013-2016 and to determine its S-index variability from the strength of its Ca II H and K line cores in order to study its characteristic cyclic chromospheric variations and determine its rotation period. We furthermore reanalyze archi…
Near-IR Transmission Spectrum of HAT-P-32b using HST/WFC3
Tsiaras, A.; Morello, G.; Damiano, M. +2 more
We report here the analysis of the near-infrared transit spectrum of the hot Jupiter HAT-P-32b, which was recorded with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. HAT-P-32b is one of the most inflated exoplanets discovered, making it an excellent candidate for transit spectroscopic measurements. To obtain the transit spect…
A novel star identification technique robust to high presence of false objects: The Multi-Poles Algorithm
Schiattarella, Vincenzo; Spiller, Dario; Curti, Fabio
This work proposes a novel technique for the star pattern recognition for the Lost in Space, named Multi-Poles Algorithm. This technique is especially designed to ensure a reliable identification of stars when there is a large number of false objects in the image, such as Single Event Upsets, hot pixels or other celestial bodies. The algorithm ide…
Probing the interstellar dust towards the Galactic Centre: dust-scattering halo around AX J1745.6-2901
Haberl, Frank; Jin, Chichuan; Ponti, Gabriele +1 more
AX J1745.6-2901 is an X-ray binary located at only 1.45 arcmin from Sgr A⋆, showcasing a strong X-ray dust-scattering halo. We combine Chandra and XMM-Newton observations to study the halo around this X-ray binary. Our study shows two major thick dust layers along the line of sight (LOS) towards AX J1745.6-2901. The LOS position and N
Excitation and evolution of vertically polarised transverse loop oscillations by coronal rain
Kohutova, P.; Verwichte, E.
Context. Coronal rain is composed of cool dense blobs that form in solar coronal loops and are a manifestation of catastrophic cooling linked to thermal instability. The nature and excitation of oscillations associated with coronal rain is not well understood.
Aims: We consider observations of coronal rain in a bid to elucidate the excitation…
Structure, Propagation, and Expansion of a CME-driven Shock in the Heliosphere: A Revisit of the 2012 July 23 Extreme Storm
Vourlidas, Angelos; Liu, Ying D.; Hu, Huidong +2 more
We examine the structure, propagation, and expansion of the shock associated with the 2012 July 23 extreme coronal mass ejection. Characteristics of the shock determined from multi-point imaging observations are compared to in situ measurements at different locations and a complex radio type II burst, which according to our definition has multiple…
X-ray burst-induced spectral variability in 4U 1728-34
Sánchez-Fernández, C.; Kuulkers, E.; Poutanen, J. +1 more
Aims: INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time it has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, also known as the slow burster. Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a br…
Breaking news from the HST: the central star of the Stingray Nebula is now returning towards the AGB
Rauch, T.; Werner, K.; Todt, H. +2 more
SAO 244567 is a rare example of a star that allows us to witness stellar evolution in real time. Between 1971 and 1990, it changed from a B-type star into the hot central star of the Stingray Nebula. This observed rapid heating has been a mystery for decades, since it is in strong contradiction with the low mass of the star and canonical post-asym…
Multi-instrument observations of a failed flare eruption associated with MHD waves in a loop bundle
Del Zanna, G.; Nakariakov, V. M.; Polito, V. +1 more
Context. We present observations of a B7.9-class flare that occurred on the 24th January, 2015, using the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO), the EUV Imaging Spectrometer (EIS) and the X-Ray Telescope of Hinode. The flare triggers the eruption of a dense cool plasma blob as seen in AIA 171 Å, which is unable…
Modifying the Standard Disk Model for the Ultraviolet Spectral Analysis of Disk-dominated Cataclysmic Variables. I. The Novalikes MV Lyrae, BZ Camelopardalis, and V592 Cassiopeiae
Blair, William P.; Sion, Edward M.; Balman, Şölen +1 more
The standard disk is often inadequate to model disk-dominated cataclysmic variables (CVs) and generates a spectrum that is bluer than the observed UV spectra. X-ray observations of these systems reveal an optically thin boundary layer (BL) expected to appear as an inner hole in the disk. Consequently, we truncate the inner disk. However, instead o…