Search Publications
Evidence of globular cluster abundance anomalies in the SMC intermediate-age cluster Kron 3
Da Costa, G. S.; Milone, A. P.; Marino, A. F. +5 more
Using spectra obtained with the VLT/FORS2 and Gemini-S/GMOS-S instruments, we have investigated carbon, nitrogen, and sodium abundances in a sample of red giant members of the Small Magellanic Cloud star cluster Kron 3. The metallicity and luminosity of the cluster are comparable to those of Galactic globular clusters but it is notably younger (ag…
The K2 Galactic Archaeology Program: Overview, target selection, and survey properties
Bland-Hawthorn, Joss; Sharma, Sanjib; Stello, Dennis +3 more
K2 was a community-driven NASA mission where all targets were proposed through guest observer programmes. Here we provide an overview of one of the largest of these endeavours, the K2 Galactic Archaeology Programme (K2GAP), with about 25 per cent of the observed targets being allocated to this programme. K2GAP provides asteroseismic parameters for…
The alignment between brightest cluster galaxies and host clusters
Yuan, Z. S.; Wen, Z. L.
The alignment between the brightest cluster galaxies (BCGs) and host clusters can reveal the mystery of the formation and evolution of galaxy clusters. We measure cluster orientations in optical based on the projected distribution of member galaxies and in X-ray by fitting the morphology of intracluster medium (ICM). Cluster orientations determine…
A holistic approach to understand helium enrichment in interplanetary coronal mass ejections: new insights
Yogesh; Chakrabarty, D.; Srivastava, N.
Despite helium abundance [AHe = (nH/nHe) × 100] being ~8 per cent at the solar photospheric/chromospheric heights, AHe can be found to exceed 8 per cent in interplanetary coronal mass ejections (ICMEs) on many occasions. Although various factors like interplanetary shocks, chromospheric evaporation, and …
Exploring the connection between ultraviolet/optical variations and radio emission in radio-quiet quasars: clues about the origin of radio emission
Liao, Mai; Wang, Junxian; Zhou, Minhua +1 more
Radio emission in radio-quiet quasars (RQQs) has long been a mystery and its physical origin remains unclear. In previous work, we have found that quasars that are more variable in ultraviolet (UV)/optical have stronger X-ray emission, indicating a link between disc turbulence and X-ray corona heating. In this work, for the first time, we investig…
A cautionary tale of Ly C escape fraction estimates from high-redshift galaxies
Ryan-Weber, E. V.; Arnouts, S.; Sawicki, M. +7 more
Measuring the escape fraction, fesc, of ionizing, Lyman continuum (Ly C) radiation is key to our understanding of the process of cosmic reionization. In this paper, we provide a methodology for recovering the posterior probability distribution of the Ly C escape fraction, $f_{\rm esc}^{\rm PDF}$, considering both the observational uncer…
V410 Puppis: A useful laboratory for early stellar evolution
Erdem, Ahmet; Sürgit, Derya; Blackford, Mark G. +6 more
New spectrometric (HERCULES) and ground-based multicolour photometric data on the multiple star V410 Puppis are combined with satellite photometry (HIPPARCOS and TESS), as well as historic astrometric observations. Absolute parameters for V410 Pup Aab are derived: MAa = 3.15 ± 0.10, MAb = 1.83 ± 0.08 (M⊙); RAa…
Hierarchical structure of YSO clusters in the W40 and Serpens South region: group extraction and comparison with fractal clusters
Wang, Hongchi; Gutermuth, Robert A.; Zhang, Shuinai +2 more
Young stellar clusters are believed to inherit the spatial distribution like hierarchical structures of their natal molecular cloud during their formation. However, the change of the structures between the cloud and the young clusters is not well constrained observationally. We select the W40-Serpens South region (~7 × 9 pc2) of the Aqu…
Distances, extinctions, and stellar parameters for stars in SkyMapper DR3
Lin, Jane; Casagrande, Luca; Asplund, Martin
We present a Bayesian isochrone fitting machinery to derive distances, extinctions, and stellar parameters (Teff, log g, and $\rm [Fe/H]$) for stars in the SkyMapper data release 3 (DR3) survey. We complement the latter with photometry from Gaia, 2MASS, and AllWISE, in addition to priors on parallaxes and interstellar extinction. We fin…
A multi-instrument investigation of the frequency stability of oscillations above the acoustic cut-off frequency with solar activity
Broomhall, A. -M.; Kiefer, R.; Kosak, K.
Below the acoustic cut-off frequency, oscillations are trapped within the solar interior and become resonant. However, signatures of oscillations persist above the acoustic cut-off frequency, and these travelling waves are known as pseudo-modes. Acoustic oscillation frequencies are known to be correlated with the solar cycle, but the pseudo-mode f…