Search Publications
The MAVERIC survey: a hidden pulsar and a black hole candidate in ATCA radio imaging of the globular cluster NGC 6397
Gelfand, Joseph D.; Strader, Jay; Bahramian, Arash +9 more
Using a 16.2-h radio observation by the Australia Telescope Compact Array and archival Chandra data, we found >5σ radio counterparts to four known and three new X-ray sources within the half-light radius (rh) of the Galactic globular cluster NGC 6397. The previously suggested millisecond pulsar (MSP) candidate, U18, is a steep-spectr…
The TOI-763 system: sub-Neptunes orbiting a Sun-like star
Fridlund, M.; Pätzold, M.; Rauer, H. +51 more
We report the discovery of a planetary system orbiting TOI-763(aka CD-39 7945), a V = 10.2, high proper motion G-type dwarf star that was photometrically monitored by the TESS space mission in Sector 10. We obtain and model the stellar spectrum and find an object slightly smaller than the Sun, and somewhat older, but with a similar metallicity. Tw…
First in situ detection of the CN radical in comets and evidence for a distributed source
Altwegg, Kathrin; Hänni, Nora; Rubin, Martin +4 more
Although the debate regarding the origin of the cyano (CN) radical in comets has been ongoing for many decades, it has yielded no definitive answer to date. CN could previously only be studied remotely, strongly hampering efforts to constrain its origin because of very limited spatial information. Thanks to the European Space Agency's Rosetta spac…
Computational tools for the spectroscopic analysis of white dwarfs
Zakamska, Nadia L.; Chandra, Vedant; Hwang, Hsiang-Chih +1 more
The spectroscopic features of white dwarfs are formed in the thin upper layer of their stellar photosphere. These features carry information about the white dwarf's surface temperature, surface gravity, and chemical composition (hereafter 'labels'). Existing methods to determine these labels rely on complex ab-initio theoretical models, which are …
Super-Earth ingestion can explain the anomalously high metal abundances of M67 Y2235
Liu, Fan; Church, Ross P.; Mustill, Alexander J.
We investigate the hypothesis that ingestion of a terrestrial or super-Earth planet could cause the anomalously high metal abundances seen in a turn-off star in the open cluster M67, when compared to other turn-off stars in the same cluster. We show that the mass of the convective envelope of the star is likely only 3.45 × 10^{-3} {M_{⊙ }}, and he…
Three-dimensional structure of the Sagittarius dwarf spheroidal core from RR Lyrae
Strigari, Louis E.; Ferguson, Peter S.
We obtain distances to a sample of RR Lyrae in the central core of the Sagittarius dwarf spheroidal galaxy from OGLE data. We use these distances, along with RR Lyrae from Gaia DR2, to measure the shape of the stellar distribution within the central ∼2 kpc. The best-fitting stellar distribution is triaxial, with axis ratios 1 : 0.76 : 0.43. A prol…
NGC 7469 as seen by MEGARA: new results from high-resolution IFU spectroscopy
Márquez, I.; Masegosa, J.; Cazzoli, S. +13 more
We present our analysis of high-resolution (R ∼ 20 000) GTC/MEGARA integral-field unit spectroscopic observations, obtained during the commissioning run, in the inner region (12.5 arcsec × 11.3 arcsec) of the active galaxy NGC 7469, at spatial scales of 0.62 arcsec. We explore the kinematics, dynamics, ionization mechanisms, and oxygen abundances …
The peculiar kinematics of the multiple populations in the globular cluster Messier 80 (NGC 6093)
Dalessandro, E.; Dreizler, S.; Bastian, N. +10 more
We combine MUSE spectroscopy and Hubble Space Telescope ultraviolet (UV) photometry to perform a study of the chemistry and dynamics of the Galactic globular cluster Messier 80 (M80, NGC 6093). Previous studies have revealed three stellar populations that vary not only in their light-element abundances, but also in their radial distributions, with…
A long-period (P = 61.8 d) M5V dwarf eclipsing a Sun-like star from TESS and NGTS
Jackman, James A. G.; Wheatley, Peter J.; Bayliss, Daniel +27 more
The Transiting Exoplanet Survey Satellite has produced a large number of single-transit event candidates which are being monitored by the Next Generation Transit Survey (NGTS). We observed a second epoch for the TIC-231005575 system (Tmag = 12.06 and $T_{\rm eff} = 5500 \pm 85\, \mathrm{ K}$ ) with NGTS and a third epoch with Las Cumbre…
Inferring the parallax of Westerlund 1 from Gaia DR2
Drout, Maria R.; Smith, Nathan; Stassun, Keivan G. +6 more
Westerlund 1 (Wd1) is potentially the largest star cluster in the Galaxy. That designation critically depends upon the distance to the cluster, yet the cluster is highly obscured, making luminosity-based distance estimates difficult. Using Gaia Data Release 2 (DR2) parallaxes and Bayesian inference, we infer a parallax of 0.35^{+0.07}_{-0.06} mas …