Search Publications
Exploring HNC and HCN line emission as probes of the protoplanetary disk temperature
Bosman, Arthur D.; Guzmán, Viviana V.; Long, Feng +6 more
Context. The distributions and abundances of molecules in protoplanetary disks are powerful tracers of the physical and chemical disk structures. The abundance ratios of HCN and its isomer HNC are known to be sensitive to gas temperature. Their line ratios might therefore offer a unique opportunity to probe the properties of the emitting gas.
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Probing protoplanetary disk evolution in the Chamaeleon II region
Pinte, C.; Ménard, F.; Dent, W. R. F. +13 more
Context. Characterizing the evolution of protoplanetary disks is necessary to improve our understanding of planet formation. Constraints on both dust and gas are needed to determine the dominant disk dissipation mechanisms.
Aims: We aim to compare the disk dust masses in the Chamaeleon II (Cha II) star-forming region with other regions with a…
Radial evolution of the April 2020 stealth coronal mass ejection between 0.8 and 1 AU. Comparison of Forbush decreases at Solar Orbiter and near the Earth
Dumbović, Mateja; Möstl, Christian; Davies, Emma E. +40 more
Aims: We present observations of the first coronal mass ejection (CME) observed by the Solar Orbiter spacecraft on April 19, 2020 and the associated Forbush decrease (FD) measured by the High Energy Telescope (HET). This CME is a multi-spacecraft event that was also seen near Earth the following day.
Methods: We highlight the capabilitie…
A2A: 21 000 bulge stars from the ARGOS survey with stellar parameters on the APOGEE scale
Freeman, K. C.; Bland-Hawthorn, J.; Ness, M. K. +3 more
Aims: Spectroscopic surveys have by now collectively observed tens of thousands of stars in the bulge of our Galaxy. However, each of these surveys had unique observing and data processing strategies that led to distinct stellar parameter and abundance scales. Because of this, stellar samples from different surveys cannot be directly combined…
Transient obscuration event captured in NGC 3227. I. Continuum model for the broadband spectral energy distribution
Kaastra, J. S.; Kriss, G. A.; Arav, N. +21 more
From Swift monitoring of a sample of active galactic nuclei (AGN) we found a transient X-ray obscuration event in Seyfert-1 galaxy NGC 3227, and thus triggered our joint XMM-Newton, NuSTAR, and Hubble Space Telescope (HST) observations to study this event. Here in the first paper of our series we present the broadband continuum modelling of the sp…
Propagating brightenings in small loop-like structures in the quiet-Sun corona: Observations from Solar Orbiter/EUI
Teriaca, Luca; Solanki, Sami K.; Schühle, Udo +6 more
Brightenings observed in solar extreme-ultraviolet images are generally interpreted as signatures of micro- or nanoflares occurring in the transition region or at coronal temperatures. Recent observations with the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have revealed the smallest of such brightenings (called campfires) in the quiet…
Asteroseismology of evolved stars to constrain the internal transport of angular momentum. IV. Internal rotation of Kepler-56 from an MCMC analysis of the rotational splittings
Buldgen, G.; Khan, S.; Eggenberger, P. +4 more
Context. The observations of global stellar oscillations of post-main-sequence stars by space-based photometry missions have allowed us to directly determine their internal rotation. These constraints have pointed towards the existence of angular momentum transport processes not accounted for in theoretical models. Constraining the properties of t…
Semi-regular red giants as distance indicators. I. The period-luminosity relations of semi-regular variables revisited
Mowlavi, N.; Lebzelter, T.; Trabucchi, M.
Context. Semi-regular variables (SRVs) are similar to Miras in brightness, and they also follow one or more period-luminosity relations (PLRs), though not necessarily the same one as Miras. As potential standard candles they are more challenging than Miras because of their smaller variability amplitudes and less regular light curves, but they are …
Milky Way archaeology using RR Lyrae and type II Cepheids. I. The Orphan stream in 7D using RR Lyrae stars
Lemasle, B.; Thévenin, F.; Altavilla, G. +19 more
We present a chemo-dynamical study of the Orphan stellar stream using a catalog of RR Lyrae pulsating variable stars for which photometric, astrometric, and spectroscopic data are available. Employing low-resolution spectra from the Sloan Digital Sky Survey (SDSS), we determined line-of-sight velocities for individual exposures and derived the sys…
TITANS metal-poor reference stars. I. Accurate effective temperatures and surface gravities for dwarfs and subgiants from 3D non-LTE Hα profiles and Gaia parallaxes
Smiljanic, R.; da Silva, A. R.; Giribaldi, R. E. +1 more
Context. Several large stellar spectroscopic surveys are producing enormous amounts of data that can be used to determine stellar atmospheric parameters and chemical abundances. Nonetheless, the accuracy achieved in the derived astrophysical parameters is still insufficient, mainly because of the paucity of adequate calibrators, particularly in th…