Search Publications
The role of tidal interactions in the formation of slowly rotating early-type stars in young star clusters
Wang, Li; de Grijs, Richard; Li, Chengyuan +9 more
The split main sequences found in the colour-magnitude diagrams of star clusters younger than ~600 Myr are suggested to be caused by the dichotomy of stellar rotation rates of upper main-sequence stars. Tidal interactions have been suggested as a possible explanation of the dichotomy of the stellar rotation rates. This hypothesis proposes that the…
The SunPy Project: An interoperable ecosystem for solar data analysis
Ryan, Daniel F.; Ireland, Jack; Hayes, Laura A. +6 more
The SunPy Project is a community of scientists and software developers creating an ecosystem of Python packages for solar physics. The project includes the sunpy core package as well as a set of affiliated packages. The sunpy core package provides general purpose tools to access data from different providers, read image and time series data, and t…
Isochrone fitting of Galactic globular clusters - V. NGC 6397 and NGC 6809 (M55)
Gontcharov, George A.; Mosenkov, Aleksandr V.; Khovritchev, Maxim Yu +8 more
We fit various colour-magnitude diagrams (CMDs) of the Galactic globular clusters NGC 6397 and NGC 6809 (M55) by isochrones from the Dartmouth Stellar Evolution Database (DSED) and Bag of Stellar Tracks and Isochrones (BaSTI) for α-enhanced [α/Fe] = +0.4. For the CMDs, we use data sets from Hubble Space Telescope, Gaia, Visible and Infrared Survey…
Nitrogen fractionation in ammonia and its insights into nitrogen chemistry
Caselli, P.; Pineda, J. E.; Bizzocchi, L. +1 more
Context. Observations of the nitrogen isotopic ratio 14N/15N in the interstellar medium are becoming more frequent thanks to increased telescope capabilities. However, interpreting these data is still puzzling. In particular, measurements of 14N/15N in diazenylium have revealed high levels of anti-fracti…
Winds in ultraluminous X‑ray sources: New challenges
Pinto, C.; Kosec, P.
Ultraluminous X‑ray sources (ULXs) are extreme X‑ray binaries shining above 1039 erg/s, in most cases as a consequence of super‑Eddington accretion onto neutron stars and stellar‑mass black holes accreting above their Eddington limit. This was understood after the discovery of coherent pulsations, cyclotron lines, and powerful winds. The latter wa…
UV-continuum β slopes of individual z 2-6 clumps and their evolution
Zanella, A.; Castellano, M.; Grillo, C. +11 more
We study the ultraviolet (UV) continuum β slope of a sample of 166 clumps, individual star-forming regions observed in high-redshift galaxies. They are hosted by 67 galaxies with redshift between 2 and 6.2, strongly lensed by the Hubble Frontier Fields cluster of galaxies MACS J0416.1 - 2403. The β slope is sensitive to a variety of physical prope…
Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. III. Recovery and Confirmation of a Temperate, Mildly Eccentric, Single-transit Jupiter Orbiting TOI-2010
Barclay, Thomas; Hellier, Coel; Bieryla, Allyson +48 more
Large-scale exoplanet surveys like the Transiting Exoplanet Survey Satellite (TESS) mission are powerful tools for discovering large numbers of exoplanet candidates. Single-transit events are commonplace within the resulting candidate list due to the unavoidable limitation of the observing baseline. These single-transit planets often remain unveri…
A Need to Revise Stellar Opacities from Asteroseismology of δ Scuti Stars
Walczak, Przemysław; Daszyńska-Daszkiewicz, Jadwiga; Pamyatnykh, Alexey +2 more
We construct seismic models of the four double-mode radial δ Scuti stars adopting opacities from three databases: OPAL, OP, and OPLIB. The aim is to find the models that fit the observed frequencies of the two radial modes and have the effective temperature and luminosity consistent with the observed values. Using the Bayesian analysis based on Mo…
Photometric determination of the mass accretion rates of pre-main-sequence stars. VIII. Recent star formation in NGC 299
De Marchi, G.; Vlasblom, M.
We studied the properties of the young stellar populations in the NGC 299 cluster in the Small Magellanic Cloud using observations obtained with the Hubble Space Telescope in the V, I, and Hα bands. We identified 250 stars with Hα excess exceeding 5σ and an equivalent width of the Hα emission line of at least 20 Å, which indicates that these stars…
The origin of the observed Ly α EW distribution of dwarf galaxies at z 2
Richard, Johan; Scarlata, Claudia; Hathi, Nimish +10 more
We present a rest-UV-selected sample of 32 lensed galaxies at z ~ 2 observed with joint Keck/LRIS rest-UV and Keck/MOSFIRE rest-optical spectra behind the clusters Abell 1689, MACS J0717, and MACS J1149. The sample pushes towards the faintest UV luminosities observed ($-19 \le {M_{\rm UV}} \le -17$) at this redshift. The fraction of dwarf galaxies…