Search Publications
Absolute V-band magnitudes and mass-to-light ratios of Galactic globular clusters
Hilker, M.; Baumgardt, H.; Sollima, A.
We have used Hubble Space Telescope and ground-based photometry to determine total V-band magnitudes and mass-to-light ratios of more than 150 Galactic globular clusters. We do this by summing up the magnitudes of their individual member stars, using colour-magnitude information, Gaia DR2 proper motions, and radial velocities to distinguish cluste…
Galaxy spin direction distribution in HST and SDSS show similar large-scale asymmetry
Shamir, Lior
Several recent observations using large data sets of galaxies showed non-random distribution of the spin directions of spiral galaxies, even when the galaxies are too far from each other to have gravitational interaction. Here, a data set of$\sim8.7\cdot10^3$spiral galaxies imaged byHubble Space Telescope(HST) is used to test and profile a possibl…
A SETI survey of the Vela region using the Murchison Widefield Array: Orders of magnitude expansion in search space
Tremblay, C. D.; Tingay, S. J.
Following the results of our previous low-frequency searches for extraterrestrial intelligence (SETI) using the Murchison Widefield Array (MWA), directed towards the Galactic Centre and the Orion Molecular Cloud (Galactic Anticentre), we report a new large-scale survey towards the Vela region with the lowest upper limits thus far obtained with the…
PKS 2250-351: A giant radio galaxy in Abell 3936
Seymour, N.; Leahy, D. A.; Norris, R. P. +27 more
We present a detailed analysis of the radio galaxy PKS $2250{-}351$ , a giant of 1.2 Mpc projected size, its host galaxy, and its environment. We use radio data from the Murchison Widefield Array, the upgraded Giant Metre-wavelength Radio Telescope, the Australian Square Kilometre Array Pathfinder, and the Australia Telescope Compact Array to mode…
ASKAP reveals giant radio halos in two merging SPT galaxy clusters
Johnston-Hollitt, Melanie; Akamatsu, Hiroki; Hodgson, Torrance +4 more
Early science observations from the Australian Square Kilometre Array Pathfinder (ASKAP) have revealed clear signals of diffuse radio emission associated with two clusters detected by the South Pole Telescope via their Sunyaev Zel'dovich signal: SPT CLJ0553-3342 (MACS J0553.4-3342) and SPT CLJ0638-5358 (Abell S0592) are both high-mass lensing clus…
Investigation on the mass transferring near-contact binary TT Cet
Tian, Xiao-Man; Chang, Lin-Feng
First multi-colour complete light curves and low-resolution spectra of short-period eclipsing binary TT Cet are presented. The stellar atmospheric parameters of the primary star were derived through spectra fitting as: $T_{eff}=7 091±124 {K}$, $\log g = 4.15±0.33 {cm}/s^2$, and $[Fe/H]=-0.23±0.04 dex$. The light curves were analysed using the Wils…
The stellar rotation-activity relation for a sample of SuperWASP and ASAS-SN field stars
Thiemann, Heidi B.; Norton, Andrew J.; Kolb, Ulrich C.
It is well established that late-type main-sequence (MS) stars display a relationship between X-ray activity and the Rossby number, Ro, the ratio of rotation period to the convective turnover time. This manifests itself as a saturated regime (where X-ray activity is constant) and an unsaturated regime (where X-ray activity anti-correlates with Ros…
A hundred new eclipsing binary system candidates studied in a near-infrared window in the VVV survey
Minniti, D.; Saito, R. K.; Palma, T. +4 more
We present the first results obtained from an extensive study of eclipsing binary (EB) system candidates recently detected in the VISTA Variables in the Vía Láctea (VVV) near-infrared (NIR) Survey. We analyse the VVV tile d040 in the southern part of the Galactic disc wherein the interstellar reddening is comparatively low, which makes it possible…
Investigation of the coronal heating through phase relation of solar activity indexes
Li, K. J.; Xu, J. C.; Yin, Z. Q. +2 more
The coronal heating problem is a long-standing perplexing issue. In this study, 13 solar activity indexes are used to investigate their phase relation with the sunspot number (SSN). Only three of them are found to statistically significantly lag the SSN (large-scale magnetic activity) by about one solar rotation period; the three indexes are total…
Bridging the ultraviolet and optical regions: Transformation equations between GALEX and UBV photometric systems
Bilir, S.; Ak, T.; Yontan, T. +6 more
We derive transformation equations between GALEX and UBV colours by using the reliable data of 556 stars. We present two sets of equations: as a function of (only) luminosity class and as a function of both luminosity class and metallicity. The metallicities are provided from the literature, while the luminosity classes are determined by using the…