Search Publications
A holistic review of a galactic interaction
Laporte, Chervin F. P.; Drimmel, Ronald; Johnston, Kathryn V. +3 more
Our situation as occupants of the Milky Way (MW) Galaxy, bombarded by the Sagittarius dwarf galaxy, provides an intimate view of physical processes that can lead to the dynamical heating of a galactic disc. While this evolution is instigated by Sagittarius, it is also driven by the intertwined influences of the dark matter halo and the disc itself…
Classifying stars, galaxies, and AGNs in CLAUDS + HSC-SSP using gradient boosted decision trees
Sawicki, Marcin; Goulding, Andy D.; Coupon, Jean +1 more
Classifying catalogue objects as stars, galaxies, or active galactic nuclei (AGNs) is a crucial part of any statistical study of galaxies. We describe our pipeline for binary (star/galaxy) and multiclass (star/galaxy/Type I AGN/Type II AGN) classification developed for the very deep CLAUDS + HSC-SSP u*grizy data set. Our method uses the XGBoost im…
The impact of a stealth CME on the Martian topside ionosphere
Nampoothiri, Govind G.; Thampi, Smitha V.; Pant, Tarun K. +1 more
Solar cycle 24 is one of the weakest solar cycles recorded, but surprisingly the declining phase of it had a slow coronal mass ejection (CME) that evolved without any low coronal signature and is classified as a stealth CME that was responsible for an intense geomagnetic storm at Earth (Dst = -176 nT). The impact of this space weather event on the…
Completeness of the Gaia-verse III: using hidden states to infer gaps, detection efficiencies, and the scanning law from the DR2 light curves
Everall, Andrew; Boubert, Douglas; Fraser, Jack +2 more
The completeness of the Gaia catalogues heavily depends on the status of that space telescope through time. Stars are only published with each of the astrometric, photometric, and spectroscopic data products if they are detected a minimum number of times. If there is a gap in scientific operations, a drop in the detection efficiency or Gaia deviat…
A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113
Bouchy, F.; Deleuil, M.; Helled, R. +53 more
We report the discovery of HD 110113 b (TESS object of interest-755.01), a transiting mini-Neptune exoplanet on a 2.5-d orbit around the solar-analogue HD 110113 (Teff = 5730 K). Using TESS photometry and High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities gathered by the NCORES program, we find that HD 110113 b has …
Massive young stellar objects in the Local Group irregular galaxy NGC 6822 identified using machine learning
van Loon, Jacco Th; Oliveira, Joana M.; Kinson, David A.
We present a supervised machine learning methodology to classify stellar populations in the Local Group dwarf-irregular galaxy NGC 6822. Near-IR colours (J - H, H - K, and J - K), K-band magnitudes and far-IR surface brightness (at 70 and 160 $\mu$m) measured from Spitzer and Herschel images are the features used to train a Probabilistic Random Fo…
The dependence of the hierarchical distribution of star clusters on galactic environment
Grebel, Eva K.; Smith, Linda J.; Calzetti, Daniela +15 more
We use the angular two-point correlation function (TPCF) to investigate the hierarchical distribution of young star clusters in 12 local (3-18 Mpc) star-forming galaxies using star cluster catalogs obtained with the Hubble Space Telescope (HST) as part of the Treasury Program Legacy ExtraGalactic UV Survey. The sample spans a range of different mo…
Searching for new solar twins: The Inti survey for the Northern Sky
Meléndez, Jorge; Reggiani, Henrique; Schlaufman, Kevin C. +9 more
Solar twins are key in different areas of astrophysics, however only just over a hundred were identified and well-studied in the last two decades. In this work, we take advantage of the very precise Gaia (DR2/EDR3), Tycho, and 2MASS photometric systems to create the ${{Inti}}$ survey of new solar twins in the Northern Hemisphere. The spectra of ou…
The NuSTAR extragalactic survey of the James Webb Space Telescope North Ecliptic Pole time-domain field
Alexander, D. M.; Cappelluti, N.; Gandhi, P. +17 more
We present the NuSTAR extragalactic survey of the James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-Domain Field. The survey covers a ~0.16 deg2 area with a total exposure of 681 ks acquired in a total of nine observations from three epochs. The survey sensitivities at 20 per cent of the area are 2.39, 1.14, 2.76, 1.52, a…
The nature of giant clumps in high-z discs: a deep-learning comparison of simulations and observations
Snyder, Gregory; Dekel, Avishai; Primack, Joel +4 more
We use deep learning to explore the nature of observed giant clumps in high-redshift disc galaxies, based on their identification and classification in cosmological simulations. Simulated clumps are detected using the 3D gas and stellar densities in the VELA zoom-in cosmological simulation suite, with ${\sim}25\ \rm {pc}$ maximum resolution, targe…