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On the Spectral Evolution of Hot White Dwarf Stars. II. Time-dependent Simulations of Element Transport in Evolving White Dwarfs with STELUM
Bergeron, P.; Blouin, S.; Bédard, A. +1 more
White dwarf stars are subject to various element transport mechanisms that can cause their surface composition to change radically as they cool, a phenomenon known as spectral evolution. In this paper, we undertake a comprehensive theoretical investigation of the spectral evolution of white dwarfs. First, we introduce STELUM, a new implementation …
Resolving the Core of R136 in the Optical
Rubio, Monica; Horch, Elliott P.; Vink, Jorick S. +4 more
The sharpest optical images of the R136 cluster in the Large Magellanic Cloud are presented, allowing us for the first time to resolve members of the central core, including R136a1, the most-massive star known. These data were taken using the Gemini speckle imager Zorro in medium-band filters with effective wavelengths similar to BVRI achieving an…
The 2021 outburst of the recurrent nova RS Ophiuchi observed in X-rays by the Neil Gehrels Swift Observatory: a comparative study
Ness, J. -U.; Munari, U.; Orio, M. +12 more
On 2021 August 8, the recurrent nova RS Ophiuchi (RS Oph) erupted again, after an interval of 15.5 yr. Regular monitoring by the Neil Gehrels Swift Observatory began promptly, on August 9.9 (0.37 d after the optical peak), and continued until the source passed behind the Sun at the start of November, 86 d later. Observations then restarted on day …
A New Flaring Black Widow Candidate and Demographics of Black Widow Millisecond Pulsars in the Galactic Field
Strader, Jay; Ray, Paul S.; Kerr, Matthew +4 more
We present the discovery of a new optical/X-ray source likely associated with the Fermi γ-ray source 4FGL J1408.6-2917. Its high-amplitude periodic optical variability, large spectroscopic radial-velocity semiamplitude, evidence for optical emission lines and flaring, and X-ray properties together imply the source is probably a new black widow mil…
Tidal Distortions in NGC1052-DF2 and NGC1052-DF4: Independent Evidence for a Lack of Dark Matter
van Dokkum, Pieter; Abraham, Roberto; Pasha, Imad +11 more
Two ultra-diffuse galaxies in the same group, NGC1052-DF2 and NGC1052-DF4, have been found to have little or no dark matter and to host unusually luminous globular cluster populations. Such low-mass diffuse objects in a group environment are easily disrupted and are expected to show evidence of tidal distortions. In this work, we present deep new …
An elliptical accretion disk following the tidal disruption event AT 2020zso
Gromadzki, M.; Young, D.; Inserra, C. +25 more
Aims: 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 event AT 2020zso, hosted by an active galactic nucleus (AGN; as inferred from narrow emission line diagnostics), with the aim of characterisin…
Revisiting bright δ Scuti stars and their period-luminosity relation with TESS and Gaia DR3
Bedding, Timothy R.; Murphy, Simon J.; Hey, Daniel R. +1 more
We have used NASA's TESS mission to study catalogued δ Scuti stars. We examined TESS light curves for 434 stars, including many for which few previous observations exist. We found that 62 are not δ Scuti pulsators, with most instead showing variability from binarity. For the 372 δ Scuti stars, we provide a catalogue of the period and amplitude of …
Slow Star Formation in the Milky Way: Theory Meets Observations
Ostriker, Eve C.; Evans, Neal J.; Kim, Jeong-Gyu
The observed star formation rate of the Milky Way can be explained by applying a metallicity-dependent factor to convert CO luminosity to molecular gas mass and a star formation efficiency per freefall time that depends on the virial parameter of a molecular cloud. These procedures also predict the trend of star formation rate surface density with…
Post-starburst Galaxies in the Centers of Intermediate-redshift Clusters
Richard, Johan; Mingozzi, Matilde; Fritz, Jacopo +17 more
We present results from MUSE spatially resolved spectroscopy of 21 post-starburst galaxies in the centers of eight clusters from z ~ 0.3 to z ~ 0.4. We measure spatially resolved star formation histories (SFHs), the time since quenching (t Q ), and the fraction of stellar mass assembled in the past 1.5 Gyr (µ 1.5). The…
The GAPS Programme at TNG. XXXII. The revealing non-detection of metastable He I in the atmosphere of the hot Jupiter WASP-80b
Scandariato, G.; Pagano, I.; Khodachenko, M. L. +38 more
Context. Because of its proximity to an active K-type star, the hot Jupiter WASP-80b has been identified as a possible excellent target for detecting and measuring He I absorption in the upper atmosphere.
Aims: Our aim was to look for, and eventually measure and model, metastable He I atmospheric absorption.
Methods: We observed four pri…