Search Publications
Dynamical masses and ages of Sirius-like systems
Kiman, Rocio; Brandt, Timothy D.; Li, Yiting +4 more
We measure precise orbits and dynamical masses and derive age constraints for six confirmed and one candidate Sirius-like systems, including the Hyades member HD 27483. Our orbital analysis incorporates radial velocities, relative astrometry, and Hipparcos-Gaia astrometric accelerations. We constrain the main-sequence lifetime of a white dwarf's p…
Applying wavelet analysis to the X-ray light curves of active galactic nuclei and quasi-periodic eruptions
Gallo, L. C.; Gonzalez, A. G.; Ghosh, Akshay
In this work, we examine the application of the wavelet transform to the X-ray timing analyses of active galactic nuclei (AGN) and quasi-periodic eruption sources (QPEs). Several scenarios are simulated to test the effectiveness of the wavelet analysis to stationary and non-stationary data. We find that the power spectral density (PSD) slope and t…
The spatial correlation of high-mass X-ray binaries and young star clusters in nearby star-forming galaxies
Williams, Benjamin F.; Binder, Breanna A.; Lazzarini, Margaret +2 more
We present an analysis of the two-point spatial correlation functions of high-mass X-ray binary (HMXB) and young star cluster (YSC) populations in M31 and M33. We find evidence that HMXBs are spatially correlated with YSCs to a higher degree than would be expected from random chance in both galaxies. When supplemented with similar studies in the M…
HST PanCET programme: a flat optical transmission spectrum for the Hot Jupiter WASP-101b
Mikal-Evans, Thomas; Sing, David K.; López-Morales, Mercedes +10 more
We present an optical transmission spectrum of the hot Jupiter WASP-101b. We observed three primary transits with Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph, covering a wavelength range from 0.3 to 1 $\mu$m. The observations suffer from significant systematics that we model using Gaussian Processes. Kernel selection for the …
Chemical abundances of the Typhon stellar stream
Ting, Yuan-Sen; Naidu, Rohan P.; Simon, Joshua D. +2 more
We present the first high-resolution chemical abundances of seven stars in the recently discovered high-energy stream Typhon. Typhon stars have apocentres r ≳ 100 kpc, making this the first detailed chemical picture of the Milky Way's very distant stellar halo. Though the sample size is limited, we find that Typhon's chemical abundances are more l…
Decoding the age-chemical structure of the Milky Way disc: an application of copulas and elicitable maps
Bovy, Jo; Frankel, Neige; Leung, Henry W. +2 more
In the Milky Way, the distribution of stars in the [α/Fe] versus [Fe/H] and [Fe/H] versus age planes holds essential information about the history of star formation, accretion, and dynamical evolution of the Galactic disc. We investigate these planes by applying novel statistical methods called copulas and elicitable maps to the ages and abundance…
Morphologies and Central Stars of Planetary Nebulae in the Galactic bulge from VLT, HST and Pan-STARRS imaging
Parker, Quentin A.; Ritter, Andreas; Zijlstra, Albert +1 more
This is the first in a series of papers that present sets of different results for 136 compact, known planetary nebulae within a 10 × 10 degree region of the Galactic bulge. We use a large, previously unpublished sample of our own extensive ESO 8-m VLT deep imaging and spectroscopic data. This is combined with archival deep Hubble Space Telescope …
The role of tidal interactions in the formation of slowly rotating early-type stars in young star clusters
Wang, Li; de Grijs, Richard; Li, Chengyuan +9 more
The split main sequences found in the colour-magnitude diagrams of star clusters younger than ~600 Myr are suggested to be caused by the dichotomy of stellar rotation rates of upper main-sequence stars. Tidal interactions have been suggested as a possible explanation of the dichotomy of the stellar rotation rates. This hypothesis proposes that the…
Isochrone fitting of Galactic globular clusters - V. NGC 6397 and NGC 6809 (M55)
Gontcharov, George A.; Mosenkov, Aleksandr V.; Khovritchev, Maxim Yu +8 more
We fit various colour-magnitude diagrams (CMDs) of the Galactic globular clusters NGC 6397 and NGC 6809 (M55) by isochrones from the Dartmouth Stellar Evolution Database (DSED) and Bag of Stellar Tracks and Isochrones (BaSTI) for α-enhanced [α/Fe] = +0.4. For the CMDs, we use data sets from Hubble Space Telescope, Gaia, Visible and Infrared Survey…
UV-continuum β slopes of individual z 2-6 clumps and their evolution
Zanella, A.; Castellano, M.; Grillo, C. +11 more
We study the ultraviolet (UV) continuum β slope of a sample of 166 clumps, individual star-forming regions observed in high-redshift galaxies. They are hosted by 67 galaxies with redshift between 2 and 6.2, strongly lensed by the Hubble Frontier Fields cluster of galaxies MACS J0416.1 - 2403. The β slope is sensitive to a variety of physical prope…