Search Publications
A combined X-ray, optical, and radio view of the merging galaxy cluster MACS J0417.5-1154
Simionescu, A.; Limousin, M.; Raychaudhury, S. +3 more
We present a comprehensive multiwavelength analysis of the merging galaxy cluster MACS J0417.5-1154 at a redshift of z = 0.44, using available images red obtained with Chandra in X-ray, Subaru, Hubble Space Telescope (HST) in optical, Giant Metrewave Radio Telescope (GMRT) in radio, and Bolocam at 2.1 mm wavelength. This is an example of a complex…
Multiple populations in integrated light spectroscopy of intermediate-age clusters
Salaris, Maurizio; Kamann, Sebastian; Schiavon, Ricardo P. +9 more
The presence of star-to-star light-element abundance variations (also known as multiple populations, MPs) appears to be ubiquitous within old and massive clusters in the Milky Way and all studied nearby galaxies. Most previous studies have focused on resolved images or spectroscopy of individual stars, although there has been significant effort in…
Evolution of X-ray irradiation during the 1999-2000 outburst of the black hole binary XTE J1859 + 226
Done, Chris; Kimura, Mariko
X-ray irradiation in X-ray binaries is thought to control the behaviour at the outer disc, which is observable mainly at optical wavelengths. It is generally parametrized phenomenologically, but it can also be predicted from theoretical models of irradiated discs and their coronae/winds. We test these models using five multiwavelength Hubble Space…
Study of the mass-ratio distribution of spectroscopic binaries - II. The boundaries of the brown-dwarf desert as seen with the APOGEE spectroscopic binaries
Mazeh, T.; Shahaf, S.
Analysis of APOGEE DR12 stellar radial velocities by Troup et al. affirmed the existence of the well-known brown-dwarf desert (BDD). They detected a dearth of spectroscopic binaries (SB) with periods shorter than ∼10-30 d and secondaries with masses in the range of ∼0.01-0.1 M_{\odot }. We reconsider here their sample of binaries, focusing on 116 …
SuperWASP dispositions and false positive catalogue
Bouchy, F.; Deleuil, M.; Queloz, D. +32 more
SuperWASP, the Northern hemisphere WASP observatory, has been observing the skies from La Palma since 2004. In that time, more than 50 planets have been discovered with data contributions from SuperWASP. In the process of validating planets, many false-positive candidates have also been identified. The TESS telescope is set to begin observations o…
The HST large programme on NGC 6752 - III. Detection of the peak of the white dwarf luminosity function
Salaris, M.; Apai, D.; Anderson, J. +10 more
We report on the white dwarf (WD) cooling sequence of the old globular cluster NGC 6752, which is chemically complex and hosts a blue horizontal branch. This is one of the last globular cluster WD cooling sequences accessible to imaging by the Hubble Space Telescope. Our photometry and completeness tests show that we have reached the peak of the l…
The `Big Dipper': the nature of the extreme variability of the AGN SDSS J2232-0806
MacLeod, Chelsea L.; Landt, Hermine; Kynoch, Daniel +3 more
SDSS J2232-0806 (the `Big Dipper') has been identified as a `slow-blue nuclear hypervariable': a galaxy with no previously known active nucleus, blue colours, and large-amplitude brightness evolution occurring on a time-scale of years. Subsequent observations have shown that this source does indeed contain an active galactic nucleus (AGN). Our opt…
Keck HIRES spectroscopy of SkyMapper commissioning survey candidate extremely metal-poor stars
Schmidt, B. P.; Da Costa, G. S.; Marino, A. F. +11 more
We present results from the analysis of high-resolution spectra obtained with the Keck HIRES spectrograph for a sample of 17 candidate extremely metal-poor (EMP) stars originally selected from commissioning data obtained with the SkyMapper telescope. Fourteen of the stars have not been observed previously at high dispersion. Three have [Fe/H] ≤ -3…
Anomalous behaviour of the UV-optical continuum bands in NGC 5548
Knigge, C.; Kriss, G. A.; Starkey, D. A. +8 more
During the 2014 HST/Swift and ground-based multiwavelength monitoring campaign of NGC 5548 [active galactic nucleus (AGN) STORM], the UV-optical broad emission lines exhibited anomalous, decorrelated behaviour relative to the far-UV continuum flux variability. Here, we use key diagnostic emission lines (Ly α and He II) for this campaign to infer a…
An all-sky search for R Coronae Borealis stars in ASAS-SN
Kochanek, C. S.; Stanek, K. Z.; Dong, Subo +6 more
We report the discovery of 19 new R Coronae Borealis (RCB) star and DY Per candidates with light curves from the All-Sky Automated Survey for Supernovae. We examined both an existing set of 1602 near/mid-infrared (IR) selected candidates and an additional 2615 candidates selected to have near/mid-IR spectral energy distributions consistent with th…