Search Publications
Search for 7Be in the outbursts of four recent novae
Bonifacio, P.; Hernanz, M.; Molaro, P. +3 more
Following the recent detection of 7Be II in the outburst spectra of classical novae, we report the search for this isotope in the outbursts of four recent bright novae by means of high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) observations. The 7Be II λλ313.0583, 313.1228 nm doublet resonance lines are det…
TESS light curves of γ Cas stars
Nazé, Yaël; Rauw, Gregor; Pigulski, Andrzej
γ Cas stars constitute a subgroup of Be stars showing unusually hard and bright X-ray emission. In search for additional peculiarities, we analysed the TESS light curves of 15 γ Cas analogues. Their periodograms display broad frequency groups and/or narrow isolated peaks, often superimposed over red noise. The detected signals appear at low freque…
The orbital phase space of contracted dark matter haloes
Grand, Robert J. J.; Marinacci, Federico; Deason, Alis J. +4 more
We study the orbital phase space of dark matter (DM) haloes in the AURIGA suite of cosmological hydrodynamics simulations of Milky Way (MW) analogues. We characterize haloes by their spherical action distribution, $F\left(J_{{r}},L\right)$ , a function of the specific angular momentum, L, and the radial action, Jr, of the DM particles. …
Formation pathway for lonely stripped-envelope supernova progenitors: implications for Cassiopeia A
Sato, Toshiki; Podsiadlowski, Philipp; Mandel, Ilya +2 more
We explore a new scenario for producing stripped-envelope supernova progenitors. In our scenario, the stripped-envelope supernova is the second supernova of the binary, in which the envelope of the secondary was removed during its red supergiant phase by the impact of the first supernova. Through 2D hydrodynamical simulations, we find that ∼50-90 …
A catalogue of over 10 million variable source candidates in ZTF Data Release 1
Gal-Yam, Avishay; Ofek, Eran O.; Masci, Frank +4 more
Variable sources probe a wide range of astrophysical phenomena. We present a catalogue of over 10 million variable source candidates found in Data Release 1 (DR1) of the Zwicky Transient Facility (ZTF). We perform a periodicity search up to a frequency of 160 d-1, and we classify the light curves into erratic and smooth variables. We al…
Zodiacal exoplanets in time - XI. The orbit and radiation environment of the young M dwarf-hosted planet K2-25b
Kuzuhara, M.; Tamura, M.; Kudo, T. +20 more
M dwarf stars are high-priority targets for searches for Earth-size and potentially Earth-like planets, but their planetary systems may form and evolve in very different circumstellar environments than those of solar-type stars. To explore the evolution of these systems, we obtained transit spectroscopy and photometry of the Neptune-size planet or…
Precision angular diameters for 16 southern stars with VLTI/PIONIER
White, Timothy R.; Casagrande, Luca; Ireland, Michael J. +2 more
In the current era of Gaia and large, high signal-to-noise stellar spectroscopic surveys, there is an unmet need for a reliable library of fundamentally calibrated stellar effective temperatures based on accurate stellar diameters. Here, we present a set of precision diameters and temperatures for a sample of 6 dwarf, 5 sub-giant, and 5 giant star…
Optical, X-ray, and γ-ray observations of the candidate transitional millisecond pulsar 4FGL J0427.8-6704
Dhillon, V. S.; Kerr, M.; Marsh, T. R. +7 more
We present an optical, X-ray, and γ-ray study of 1SXPS J042749.2-670434, an eclipsing X-ray binary that has an associated γ-ray counterpart, 4FGL J0427.8-6704. This association has led to the source being classified as a transitional millisecond pulsar (tMSP) in an accreting state. We analyse 10.5 yr of Fermi LAT data and detect a γ-ray eclipse at…
Direct collapse to supermassive black hole seeds: the critical conditions for suppression of H2 cooling
Fang, Taotao; Nagamine, Kentaro; Shlosman, Isaac +1 more
Observations of high-redshift quasars imply the presence of supermassive black holes (SMBHs) already at z ∼ 7.5. An appealing and promising pathway to their formation is the direct collapse scenario of a primordial gas in atomic-cooling haloes at z ∼ 10-20, when the H2 formation is inhibited by a strong background radiation field, whose…
The dynamics of the γ Vel cluster and nearby Vela OB2 association
Wright, Nicholas J.; Jeffries, R. D.; Jackson, R. J. +1 more
The kinematics of low-mass stars in nearby OB associations can provide clues about their origins and evolution. Combining the precise positions, proper motions, and parallaxes given in the second Gaia Data Release with radial-velocity measurements obtained with the Hermes spectrograph at the Anglo-Australian Telescope, we have an opportunity to st…