Search Publications
Calibration of metallicity of LAMOST M dwarf stars using FGK+M wide binaries
Tian, Haijun; Qiu, Dan; Niu, Zexi +3 more
Estimating precise metallicity of M dwarfs is a well-known difficult problem due to their complex spectra. In this work, we empirically calibrate the metallicity using wide binaries with a F, G, or K dwarf and a M dwarf companion. With 1308 FGK+M wide binaries well observed by LAMOST, we calibrated M dwarf's [Fe/H] by using the Stellar LAbel Machi…
Geometry of the LMC based on multiphase analysis of multiwavelength Cepheid light curves using OGLE-IV and Gaia DR3 data
Deb, Sukanta; Kanbur, Shashi M.; Bhardwaj, Anupam +3 more
The period-luminosity (PL) relation of Cepheids in the Large Magellanic Cloud (LMC) plays a pivotal role in extragalactic distance measurement and the determination of the Hubble constant (H0). In this work, we probe the geometry of the LMC through a detailed study of multiphase PL relations of these Cepheids, leveraging data from the O…
Doppler imaging of a southern ApSi star HD 152564
Potravnov, I.; Ryabchikova, T.; Piskunov, N. +2 more
We present the results of the spectroscopic study of a chemically peculiar star HD 152564. Using medium-resolution (R = 37 000) observations obtained with the high-resolution fibre échelle spectrograph mounted on the South African Large Telescope, we determined atmospheric parameters Teff = 11 950 ± 200 K and log g = 3.6 ± 0.2 dex. Abun…
An extreme ultra-compact X-ray binary in a globular cluster: multiwavelength observations of RZ 2109 explored in a triple system framework
Kundu, Arunav; Dage, Kristen C.; Zepf, Stephen E. +6 more
The globular cluster ultraluminous X-ray source, RZ 2109, is a complex and unique system that has been detected at X-ray, ultraviolet, and optical wavelengths. Based on almost 20 yr of Chandra and XMM-Newton observations, the X-ray luminosity exhibits order of magnitude variability, with the peak flux lasting on the order of a few hours. We perfor…
Hidden cooling flows - IV. More details on Centaurus and the efficiency of AGN feedback in clusters
Fabian, A. C.; Pinto, C.; Hlavacek-Larrondo, J. +7 more
Cooling flows are common in galaxy clusters which have cool cores. The soft X-ray emission below 1 keV from the flows is mostly absorbed by cold dusty gas within the central cooling sites. Further evidence for this process is presented here through a more detailed analysis of the nearby Centaurus cluster and some additional clusters. Predictions o…
TIC 378898110: A bright, short-period AM CVn binary in TESS
Kepler, S. O.; Hermes, J. J.; Dhillon, V. S. +22 more
AM CVn-type systems are ultracompact, helium-accreting binary systems that are evolutionarily linked to the progenitors of thermonuclear supernovae and are expected to be strong Galactic sources of gravitational waves detectable to upcoming space-based interferometers. AM CVn binaries with orbital periods ≲20-23 min exist in a constant high state …
Mitigating bias in deep learning: training unbiased models on biased data for the morphological classification of galaxies
Miller, Christopher J.; Medina-Rosales, Esteban; Cabrera-Vives, Guillermo
Galaxy morphologies and their relation with physical properties have been a relevant subject of study in the past. Most galaxy morphology catalogues have been labelled by human annotators or by machine learning models trained on human-labelled data. Human-generated labels have been shown to contain biases in terms of the observational properties o…
The 2022-2023 accretion outburst of the young star V1741 Sgr
Rich, R. Michael; De, Kishalay; Fremling, Christoffer +12 more
V1741 Sgr (= SPICY 71482/Gaia22dtk) is a Classical T Tauri star on the outskirts of the Lagoon Nebula. After at least a decade of stability, in mid-2022, the optical source brightened by ~3 mag over 2 months, remained bright until early 2023, then dimmed erratically over the next 4 months. This event was monitored with optical and infrared spectro…
An optimal ALMA image of the Hubble Ultra Deep Field in the era of JWST: obscured star formation and the cosmic far-infrared background
Hill, Ryley; Dunlop, James S.; Scott, Douglas +3 more
We combine archival ALMA data targeting the Hubble Ultra Deep Field (HUDF) to produce the deepest currently attainable 1-mm maps of this key region. Our deepest map covers 4.2 arcmin2, with a beamsize of 1.49 arcsec $\, {\times }\, 1.07\,$ arcsec at an effective frequency of 243 GHz (1.23 mm). It reaches an rms of 4.6 µJy beam$^{-…
Molecular clouds as hubs in spiral galaxies: gas inflow and evolutionary sequence
Davis, Timothy A.; Dib, Sami; Zhou, J. W.
We decomposed the molecular gas in the spiral galaxy NGC 628 (M74) into multiscale hub-filament structures using the CO (2