Hae
Aineistot 21-30 / 45
An elliptical accretion disk following the tidal disruption event AT 2020zso
<p><strong>Aims</strong>. The modelling of spectroscopic observations of tidal disruption events (TDEs) to date suggests that the newly formed accretion disks are mostly quasi-circular. In this work we study the transient ...
Status of the PSF Reconstruction Work Package for MICADO@ELT
MICADO is a workhorse instrument for the ESO ELT, allowing first light capability for diffraction limited imaging and long-slit spectroscopy at near-infrared wavelengths. The PSF Reconstruction (PSF-R) Team of MICADO is ...
Forbidden hugs in pandemic times III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631
<p> We present an observational study of the luminous red nova (LRN) AT 2021biy in the nearby galaxy NGC 4631. The field of the object was routinely imaged during the pre-eruptive stage by synoptic surveys, but the transient was detected only at a few epochs from ∼231 days before maximum brightness. The LRN outburst was monitored with unprecedented cadence both photometrically and spectroscopically. AT 2021biy shows a short-duration blue peak, with a bolometric luminosity of ∼1.6 × 10<sup>41</sup> erg s<sup>−1</sup>, followed by the longest plateau among LRNe to date, with a duration of 210 days. A late-time hump in the light curve was also observed, possibly produced by a shell-shell collision. AT 2021biy exhibits the typical spectral evolution of LRNe. Early-time spectra are characterised by a blue continuum and prominent H emission lines. Then, the continuum becomes redder, resembling that of a K-type star with a forest of metal absorption lines during the plateau phase. Finally, late-time spectra show a very red continuum (T<sub>BB</sub> ≈ 2050 K) with molecular features (e.g., TiO) resembling those of M-type stars. Spectropolarimetric analysis indicates that AT 2021biy has local dust properties similar to those of V838 Mon in the Milky Way Galaxy. Inspection of archival Hubble Space Telescope data taken on 2003 August 3 reveals a ∼20 M<sub>⊙</sub> progenitor candidate with log (L/L<sub>⊙</sub>) = 5.0 dex and T<sub>eff</sub> = 5900 K at solar metallicity. The above luminosity and colour match those of a luminous yellow supergiant. Most likely, this source is a close binary, with a 17–24 M<sub>⊙</sub> primary component. <br></p>...
First results from GeMS/GSAOI for project SUNBIRD: Supernovae UNmasked By Infra-Red Detection
Core collapse supernova (CCSN) rates suffer from large uncertainties as many CCSNe exploding in regions of bright background emission and significant dust extinction remain unobserved. Such a shortfall is particularly ...
MAGIC detection of very high energy gamma-ray emission from the low-luminosity blazar 1ES 1741+196
We present the first detection of the nearby (z = 0.084) low-luminosity BL Lac object 1ES 1741+196 in the very high energy (E > 100 GeV) band. This object lies in a triplet of interacting galaxies. Early predictions had ...
Solar-insolation-induced changes in the coma morphology of comet 67P/Churyumov-Gerasimenko Optical monitoring with the Nordic Optical Telescope
Context. 67P/Churyumov-Gerasimenko (67P/C-G) is a short-period Jupiter family comet with an orbital period of 6.55 yr. Being the target comet of ESA's Rosetta mission, 67P/C-G has become one of the most intensively studied ...
Long-period quasi-periodic oscillations of a small-scale magnetic structure on the Sun
Aims. Long-period quasi-periodic variations of the average magnetic field in a small-scale magnetic structure on the Sun are analysed. The structure is situated at the photospheric level and is involved in a facula formation ...
Formation of Radio Type II Bursts During a Multiple Coronal Mass Ejection Event
<p>We study the solar event on 27 September 2001 that consisted of three
consecutive coronal mass ejections (CMEs) originating from the same
active region, which were associated with several periods of radio type
II ...
Large-scale environments of narrow-line Seyfert 1 galaxies
Studying large-scale environments of narrow-line Seyfert 1 (NLS1) galaxies gives a new perspective on their properties, particularly their radio loudness. The large-scale environment is believed to have an impact on the ...
Detection of persistent VHE gamma-ray emission from PKS 1510-089 by the MAGIC telescopes during low states between 2012 and 2017
Context. PKS 1510-089 is a flat spectrum radio quasar strongly variable in the optical and GeV range. To date, very high-energy (VHE, >100 GeV) emission has been observed from this source either during long high states of ...