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Assessment of the accuracy of measures in the 1829 southern double star catalogue of James Dunlop
Letchford, Roderick R.; White, Graeme L.; Brown, Carolyn J.
In 1829 James Dunlop published the first southern double star catalogue of some 253 double stars. The accuracy of this catalogue has been determined by using Aladin to cross-match them with Gaia DR2 and estimate their positional (right ascension, declination, position angle, and separation) and magnitude accuracy. Seven per cent could not be ident…
Fragmented atomic shell around S187 H II region and its interaction with molecular and ionized gas
Ghosh, Swarna K.; Dewangan, Lokesh K.; Ojha, Devendra K. +6 more
The environment of S187, a nearby H II region (1.4 ± 0.3 kpc), is analyzed. A surrounding shell has been studied in the H I line, molecular lines, and also in infrared and radio continua. We report the first evidence of a clumpy H I environment in its photodissociation region. A background radio galaxy enables the estimation of the properties of c…
η Geminorum: an eclipsing semiregular variable star orbited by a companion surrounded by an extended disc
Torres, Guillermo; Sakano, Kristy
We report 11 yr of spectroscopic monitoring of the M-type asymptotic giant branch star η Gem, a semiregular variable and a known spectroscopic binary with a period of 8.2 yr. We combine our radial velocities with others from the literature to provide an improved spectroscopic orbital solution, giving a period of 2979 d, which we then use to predic…
Deep Extragalactic VIsible Legacy Survey: Data Release 1 blended spectra search for candidate strong gravitational lenses
Holwerda, B. W.; Davies, L. J. M.; Siudek, M. +3 more
Here, we present a catalogue of blended spectra in Data Release 1 of the Deep Extragalactic VIsible Legacy Survey (DEVILS) on the Anglo-Australian Telescope. Of the 23 197 spectra, 181 showed signs of a blend of redshifts and spectral templates. We examine these blends in detail for signs of either a candidate strong lensing galaxy or a useful ove…
Plateaus, dips, and rebrightenings during the outbursts of WZ Sge: no magnetic propeller, but a veiling curtain
Knigge, C.; Castro Segura, N.; Long, K. S. +1 more
WZ Sge is the prototype of highly evolved, low-accretion rate dwarf novae (DNe). During the decline from eruptions, its light curve displays a 'dip' followed by ≃10 'echo outbursts'. The standard disc instability model does not account for this behaviour, which is also seen in other low-accretion rate DNe. One recent interpretation for these rapid…
Probing cool giants in unresolved galaxies using fluctuation eigenspectra: A demonstration using high-resolution MUSE observations of NGC 5128
Smith, Russell J.
I describe and demonstrate a new approach to using spectroscopic data to exploit Poisson sampling fluctuations in unresolved stellar populations. The method is introduced using spectra predicted for independent samples of stars from a 10 Gyr population using a simple stochastic spectral synthesis model. A principal components analysis shows that &…
The MAVERIC Survey: The first radio and X-ray limits on the detached black holes in NGC 3201
Kamann, Sebastian; Dreizler, Stefan; Strader, Jay +11 more
The Galactic globular cluster (GC) NGC 3201 is the first Galactic GC observed to host dynamically confirmed stellar-mass black holes (BHs), containing two confirmed and one candidate BH. This result indicates that GCs can retain BHs, which has important implications for GC evolution. NGC 3201 has been observed as part of the MAVERIC survey of Gala…
A Suzaku sample of unabsorbed narrow-line and broad-line Seyfert 1 galaxies - II. Iron emission and absorption
Gallo, L. C.; Waddell, S. G. H.
A sample of 22 narrow-line type 1 Seyfert (NLS1) and 47 broad-line type 1 Seyfert (BLS1) galaxies observed with Suzaku is used to examine the Fe K-band properties of each group. Three different models are used to examine the presence of: narrow neutral Fe K α line at $6.4{\rm \, keV}$ and ionized Fe XXV and Fe XXVI emission lines (model A); a broa…
Detailed evolutionary models for twins in sight of new spectral data: AN Cam, RS Ari, and V455 Aur
Bakış, Volkan; Yücel, Gökhan
We present the evolutionary scenarios for three eclipsing twin (q(M2/M1) ~1) binary systems using their combined spectroscopic and photometric data. Using accurate TESS photometric data, RV measurements, and spectroscopic data enabled us to calculate fundamental parameters, such as mass and radius, better than 2 per cent. The…
Using machine learning to identify extragalactic globular cluster candidates from ground-based photometric surveys of M87
Clarkson, William I.; Kundu, Arunav; Dage, Kristen C. +6 more
Globular clusters (GCs) have been at the heart of many longstanding questions in many sub-fields of astronomy and, as such, systematic identification of GCs in external galaxies has immense impacts. In this study, we take advantage of M87's well-studied GC system to implement supervised machine learning (ML) classification algorithms - specificall…