Search Publications
Calibration of the convective parameters in stellar pulsation hydrocodes
Szabó, Róbert; Kovács, Gábor B.; Nuspl, János
Despite the appearance of two- and three-dimensional models thanks to the rapid growth of computing performance, numerical hydrocodes used to model radial stellar pulsations (RSPs) still apply a one-dimensional stellar envelope model without any realistic atmosphere, in which a significant improvement was the inclusion of turbulent convection. How…
A Bayesian estimation of the Milky Way's circular velocity curve using Gaia DR3
Thomas, Guillaume F.; Kipper, Rain; Kolka, Indrek +5 more
Aims: Our goal is to calculate the circular velocity curve of the Milky Way, along with corresponding uncertainties that quantify various sources of systematic uncertainty in a self-consistent manner.
Methods: The observed rotational velocities are described as circular velocities minus the asymmetric drift. The latter is described by th…
Numerical Simulations and Observations of Mg II in the Solar Chromosphere
De Pontieu, Bart; Carlsson, Mats; Hansteen, Viggo H. +3 more
The Mg II h and k lines are among the best diagnostic tools of the upper solar chromosphere. This region of the atmosphere is of particular interest, as it is the lowest region of the Sun's atmosphere where the magnetic field is dominant in the energetics and dynamics, defining its structure. While highly successful in the photosphere and lower to…
TOI-199 b: A Well-characterized 100 day Transiting Warm Giant Planet with TTVs Seen from Antarctica
Trifonov, Trifon; Henning, Thomas; Latham, David W. +49 more
We present the spectroscopic confirmation and precise mass measurement of the warm giant planet TOI-199 b. This planet was first identified in TESS photometry and confirmed using ground-based photometry from ASTEP in Antarctica including a full 6.5 hr long transit, PEST, Hazelwood, and LCO; space photometry from NEOSSat; and radial velocities (RVs…
Improving the selection of changing-look AGNs through multiwavelength photometric variability
Stern, D.; Salvato, M.; Merloni, A. +13 more
We present second epoch optical spectra for 30 changing-look (CL) candidates found by searching for Type-1 optical variability in a sample of active galactic nuclei (AGNs) spectroscopically classified as Type 2. We use a random-forest-based light-curve classifier and spectroscopic follow-up, confirming 50 per cent of candidates as turning-on CLs. …
Low-ionization structures in planetary nebulae - II. Densities, temperatures, abundances, and excitation of six PNe
Gonçalves, Denise R.; Akras, Stavros; Mari, M. Belén
Here we present the spatially resolved study of six Galactic planetary nebulae (PNe), namely IC 4593, Hen 2-186, Hen 2-429, NGC 3918, NGC 6543, and NGC 6905, from intermediate-resolution spectra of the 2.5 m Isaac Newton Telescope and the 1.54 m Danish telescope. The physical conditions (electron densities, Ne, and temperatures, Te…
3D chemical structure of the diffuse turbulent interstellar medium. II. The origin of CH+: A new solution to an 80-year mystery
Godard, B.; Hennebelle, P.; Pineau des Forêts, G. +2 more
Aims: The high abundances of CH+ in the diffuse interstellar medium (ISM) are a long-standing issue of our understanding of the thermodynamical and chemical states of the gas. We investigate here the formation of CH+ in turbulent and multiphase environments, where the heating of the gas is almost solely driven by the photoelectric …
Saturn's Atmosphere in Northern Summer Revealed by JWST/MIRI
Fletcher, Leigh N.; Hedman, Matthew M.; Guerlet, Sandrine +8 more
Saturn's northern summertime hemisphere was mapped by JWST/Mid-Infrared Instrument (4.9-27.9 µm) in November 2022, tracing the seasonal evolution of temperatures, aerosols, and chemical species in the 5 years since the end of the Cassini mission. The spectral region between reflected sunlight and thermal emission (5.1-6.8 µm) is mapped for the fir…
Raising the observed metallicity floor with a 3D non-LTE analysis of SDSS J102915.14+172927.9
Hansen, T. T.; Amarsi, A. M.; Lind, K. +4 more
Context. The first stars marked the end of the cosmic dark ages, produced the first heavy elements, and set the stage for the formation of the first galaxies. Accurate chemical abundances of ultra metal-poor stars ([Fe/H] < −4) can be used to infer the properties of the first stars and thus the formation mechanism for low-mass second-generation…
Revised orbits of the two nearest Jupiters
Butler, R. Paul; Vogt, Steven S.; Holden, Bradford +2 more
With its near-to-mid-infrared high-contrast imaging capabilities, JWST is ushering us into a golden age of directly imaging Jupiter-like planets. As the two closest cold Jupiters, ɛ Ind A b and ɛ Eridani b have sufficiently wide orbits and adequate infrared emissions to be detected by JWST. To detect more Jupiter-like planets for direct imaging, w…