Search Publications
Period-change rates in Large Magellanic Cloud Cepheids revisited
Catelan, M.; Orquera-Rojas, C.; Torres, P. +10 more
The period-change rate (PCR) of pulsating variable stars is a useful probe of changes in their interior structure, and thus of their evolutionary stages. So far, the PCRs of classical Cepheids in the Large Magellanic Cloud (LMC) have been explored in a limited sample of the total population of these variables. Here, we use a template-based method …
The halo around HD 32297: µm-sized cometary dust
Bayo, A.; Olofsson, J.; Thébault, P. +1 more
Context. The optical properties of the second generation dust that we observe in debris disks remain quite elusive, whether it is the absorption efficiencies at millimeter wavelengths or the (un)polarized phase function at near-infrared wavelengths. Thankfully, the same particles are experiencing forces that are size dependent (e.g., radiation pre…
Determination of coronal mass ejection orientation and consequences for their propagation
Temmer, M.; Vršnak, B.; Veronig, A. +2 more
Context. The configuration of the interplanetary magnetic field and features of the related ambient solar wind in the ecliptic and meridional plane are different. Therefore, one can expect that the orientation of the flux-rope axis of a coronal mass ejection (CME) influences the propagation of the CME itself. However, the determination of the CME …
An expanded ultraluminous X-ray source catalogue
Zezas, A.; Schwope, A. D.; Traulsen, I. +2 more
Context. Ultraluminous X-ray sources (LX ≳ ×1039 erg s−1, ULXs) are excellent probes for extreme accretion physics, star formation history in galaxies, and intermediate-mass black holes searches. As the sample size of X-ray data from modern observatories such as XMM-Newton and Chandra increases, producing extensive…
The VMC survey - XLVII. Turbulence-controlled hierarchical star formation in the Large Magellanic Cloud
Sun, Ning-Chen; de Grijs, Richard; Marconi, Marcella +9 more
We perform a statistical clustering analysis of upper main-sequence stars in the Large Magellanic Cloud (LMC) using data from the Visible and Infrared Survey Telescope for Astronomy survey of the Magellanic Clouds. We map over 2500 young stellar structures at 15 significance levels across ~120 square degrees centred on the LMC. The structures have…
Forecasting cosmic acceleration measurements using the Lyman-α forest
Liske, Jochen; Gonzalez, Anthony; Dong, Chenxing +5 more
We present results from end-to-end simulations of observations designed to constrain the rate of change in the expansion history of the Universe using the redshift drift of the Lyman-α forest absorption lines along the lines of sight towards bright quasars. For our simulations, we take Lyman-α forest lines extracted from Keck/HIRES spectra of brig…
The centre-to-limb variation of non-thermal velocities using IRIS Si IV
Del Zanna, Giulio; Rao, Yamini K.; Mason, Helen E.
We study the non-thermal velocities in the quiet Sun using various high spatial, temporal, and spectral resolution observations from the Interface Region Imaging Spectrograph (IRIS). We focus our analysis on the transition region using the optically thin line (Si IV 1393.7 Å), and select line profiles that are nearly Gaussian. We find evidence of …
Exploring Changes in Quasar Spectral Energy Distributions across C IV Parameter Space
Gallagher, Sarah C.; Richards, Gordon T.; Shemmer, Ohad +4 more
We examine the UV/X-ray properties of 1378 quasars in order to link empirical correlations to theoretical models of the physical mechanisms dominating quasars as a function of mass and accretion rate. The clarity of these correlations is improved when (1) using C IV broad emission line equivalent width (EQW) and blueshift (relative to systemic) va…
Spatially resolved gas flows around the Milky Way
Fox, Andrew J.; Bordoloi, Rongmon; Clark, Sean
We present spatially resolved measurements of cool gas flowing into and out of the Milky Way (MW), using archival ultraviolet spectra of background quasars from the Hubble Space Telescope/Cosmic Origins Spectrograph. We co-add spectra of different background sources at close projected angular separation on the sky. This novel stacking technique dr…
The Obscured Fraction of Quasars at Cosmic Noon
Sawicki, Marcin; Schramm, Malte; Gwyn, Stephen +6 more
Statistical studies of X-ray selected active galactic nuclei (AGN) indicate that the fraction of obscured AGN increases with increasing redshift, and the results suggest that a significant part of the accretion growth occurs behind obscuring material in the early universe. We investigate the obscured fraction of highly accreting X-ray AGN at aroun…