Search Publications
Gaia parallax of Milky Way globular clusters - A solution of mixture model
Li, Lu; Shao, Zhengyi
We have established a mixture model approach to derive the parallax of the Milky Way globular clusters. It avoids the problem of cluster membership determination and provides a completely independent astrometrical solution by purely using the parallax data. This method is validated with simulated clusters of Pancino et al.. We have resolved 120 re…
Planetesimals around stars with TESS (PAST) - I. Transient dimming of a binary solar analogue at the end of the planet accretion era
Vanderburg, A.; Winn, J. N.; Ansdell, M. +16 more
We report detection of quasi-periodic (1.5-d) dimming of HD 240779, the solar-mass primary in a 5 arcsec visual binary (also TIC 284730577), by the Transiting Exoplanet Survey Satellite. This dimming, as has been shown for other `dipper' stars, is likely due to occultation by circumstellar dust. The barycentric space motion, lithium abundance, rot…
Quantitative High-Resolution Reexamination of a Hypothesized Ocean Shoreline in Cydonia Mensae on Mars
Catling, David C.; Sholes, Steven F.; Montgomery, David R.
Primary support for ancient Martian oceans has relied on qualitative interpretations of hypothesized shorelines on relatively low-resolution images and data. We present a toolkit for quantitatively identifying paleoshorelines using topographic, morphological, and spectroscopic evaluations. In particular, we apply the validated topographic expressi…
Abundances of α-Process Elements in Thin-Disk, Thick-Disk, and Halo Stars of the Galaxy: Non-LTE Analysis
Sitnova, T. M.; Mashonkina, L. I.; Pakhomov, Yu. V. +1 more
The atmospheric parameters and abundances of Mg, Si, Ca, and Ti have been determined for 20 stars using the Gaia DR2 parallaxes, high-resolution spectra, and modeling of lines without assuming LTE (non-LTE modeling). A sample of stars with homogeneous data on the abundances of α-process elements has thus been increased to 94. It is shown that appl…
MUSE library of stellar spectra
Coccato, Lodovico; Ivanov, Valentin D.; Corsini, Enrico M. +5 more
Context. Empirical stellar spectral libraries have applications in both extragalactic and stellar studies, and they confer an advantage over theoretical libraries because they naturally include all relevant chemical species and physical processes. In recent years we have seen a stream of new sets of high-quality spectra, but increasing the spectra…
Galactic calibration of the tip of the red giant branch
Clementini, Gisella; Da Costa, Gary; Mould, Jeremy
Indications from Gaia data release 2 are that the tip of the red giant branch (a population II standard candle related to the helium flash in low mass stars) is close to -4 in absolute I magnitude in the Cousins photometric system. Our sample is high-latitude southern stars from the thick disk and inner halo, and our result is consistent with long…
Rotating Solar Models with Low Metal Abundances as Good as Those with High Metal Abundances
Yang, Wuming
Standard solar models (SSMs) constructed in accord with low metal abundances disagree with seismically inferred results. We constructed rotating solar models with low metal abundances that included enhanced settling and convection overshoot. In one of our rotating models, AGSSr2a, the convection overshoot allowed us to recover the radius of the ba…
Formation of coronal rain triggered by impulsive heating associated with magnetic reconnection
Kohutova, P.; Verwichte, E.; Froment, C.
Context. Coronal rain consists of cool plasma condensations formed in coronal loops as a result of thermal instability. The standard models of coronal rain formation assume that the heating is quasi-steady and localised at the coronal loop footpoints.
Aims: We present an observation of magnetic reconnection in the corona and the associated im…
Angular momentum of z ∼ 1.5 galaxies and their local analogues with adaptive optics
Glazebrook, Karl; Fisher, Deanne B.; Obreschkow, Danail +9 more
We present stellar specific angular momentum j* measurements of two z ∼ 1.5 galaxies in the KGES sample and 12 DYNAMO z ∼ 0.1 analogues of high-redshift galaxies. We combine natural seeing integral field spectroscopic data to trace line emission out to high multiples of effective radius re, with adaptive optics assisted Keck/…
K2-288Bb: A Small Temperate Planet in a Low-mass Binary System Discovered by Citizen Scientists
Schlieder, Joshua E.; Howard, Andrew W.; Petigura, Erik A. +23 more
Observations from the Kepler and K2 missions have provided the astronomical community with unprecedented amounts of data to search for transiting exoplanets and other astrophysical phenomena. Here, we present K2-288, a low-mass binary system (M2.0 ± 1.0; M3.0 ± 1.0) hosting a small (R p = 1.9 R ⊕), temperate (T eq …