Search Publications
X-ray spectra reveal the reawakening of the repeat changing-look AGN NGC 1566
Harrison, F.; Schartel, N.; Santos-Lleó, M. +6 more
We present simultaneous XMM-Newton and NuSTAR observations of the repeat changing-look AGN NGC 1566, which dramatically increased in brightness in the IR to X-ray bands in 2018. The broad-band X-ray spectrum was taken at the peak of the outburst and is typical of Seyfert 1 AGN. The spectrum shows a soft excess, Compton hump, warm absorption and re…
A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) - I. Search for exoplanets and variable stars in the field of 47 Tuc
Bedin, L. R.; Montalto, M.; Piotto, G. +9 more
The TESS mission will survey ∼85 per cent of the sky, giving us the opportunity of extracting high-precision light curves of millions of stars, including stellar cluster members. In this work, we present our project `A PSF-based Approach to TESS High quality data Of Stellar clusters' (PATHOS), aimed at searching and characterize candidate exoplane…
Chandra centres for COSMOS X-ray galaxy groups: differences in stellar properties between central dominant and offset brightest group galaxies
Daddi, Emanuele; Dolag, Klaus; Capak, Peter +24 more
We present the results of a search for galaxy clusters and groups in the ∼2 deg2 of the COSMOS field using all available X-ray observations from the XMM-Newton and Chandra observatories. We reach an X-ray flux limit of 3× 10^{-16} erg cm^{-2 s}^{-1} in the 0.5-2 keV range, and identify 247 X-ray groups with M_{ 200c}=8× 10^{12}-3× 10^{1…
Study of Lithium-rich giants with the GALAH spectroscopic survey
Deepak; Reddy, Bacham E.
In this article, we speculate on the possible mechanisms for Li enhancement origin in RGB stars based on a large data set of around 340 299 stars collected from the GALAH survey combined with the Gaia astrometry. Data has 51 982 low mass (M ≤ 2 M⊙) RGB stars with reliable atmospheric parameters. The data set shows a well-populated RGB w…
Probing the existence of very massive first stars
Salvadori, S.; Bonifacio, P.; Caffau, E. +4 more
We present a novel approach aimed at identifying the key chemical elements to search for the (missing) descendants of very massive first stars exploding as pair instability supernovae (PISN). Our simple and general method consists in a parametric study accounting for the unknowns related to early cosmic star formation and metal-enrichment. Our app…
The tidal disruption event AT2017eqx: spectroscopic evolution from hydrogen rich to poor suggests an atmosphere and outflow
Berger, E.; Challis, P.; Foley, R. J. +24 more
We present and analyse a new tidal disruption event (TDE), AT2017eqx at redshift z = 0.1089, discovered by Pan-STARRS and ATLAS. The position of the transient is consistent with the nucleus of its host galaxy; the spectrum shows a persistent blackbody temperature T ≳ 20 000 K with broad H I and He II emission; and it peaks at a blackbody luminosit…
MOBSTER - II. Identification of rotationally variable A stars observed with TESS in sectors 1-4
Wade, G. A.; Neiner, C.; Paunzen, E. +7 more
Recently, high-precision optical 2-min cadence light curves obtained with TESS for targets located in the mission's defined first four sectors have been released. The majority of these high-cadence and high-precision measurements currently span {∼ }28 d, thereby allowing periodic variability occurring on time-scales {≲ }14 d to potentially be dete…
Period spacings of γ Doradus pulsators in the Kepler field: Rossby and gravity modes in 82 stars
Li, Gang; Bedding, Timothy R.; Antoci, Victoria +2 more
Rossby modes are the oscillations in a rotating fluid, whose restoring force is the Coriolis force. They provide an additional diagnostic to understand the rotation of stars, which complicates asteroseismic modelling. We report 82 γ Doradus stars for which clear period spacing patterns of both gravity and Rossby modes have been detected. The perio…
The non-uniformity of galaxy cluster metallicity profiles
Lovisari, L.; Reiprich, T. H.
We study a sample of 207 nearby galaxy groups and clusters observed with XMM-Newton. Key aspects of this sample include the large size, the high data quality, and the large diversity of cluster dynamical states. We determine the overall metallicity within 0.3 R500 and the radial distribution of the metals. On average, we find a mild dep…
Emergence of the Gaia phase space spirals from bending waves
Widrow, Lawrence M.; Darling, Keir
We discuss the physical mechanism by which pure vertical bending waves in a stellar disc evolve to form phase space spirals similar to those discovered by Antoja et al. in Gaia Data Release 2. These spirals are found by projecting Solar Neighbourhood stars on to the z-vz plane. Faint spirals appear in the number density of stars project…