Search Publications
Tracking the Evolution of Lithium in Giants Using Asteroseismology: Super-Li-rich Stars Are Almost Exclusively Young Red-clump Stars
Vrard, Mathieu; Campbell, Simon W.; Reddy, Bacham E. +2 more
We report novel observational evidence on the evolutionary status of lithium-rich giant stars by combining asteroseismic and lithium abundance data. Comparing observations and models of the asteroseismic gravity-mode period spacing ΔΠ1, we find that super-Li-rich giants (SLRs, A(Li) > 3.2 dex) are almost exclusively young red-clump (…
LAMOST Time-Domain survey: first results of four K2 plates
Tian, Hao; Kovalev, Mikhail; Fu, Jian-Ning +23 more
From Oct. 2019 to Apr. 2020, LAMOST performed a time-domain (TD) spectroscopic survey of four K2 plates with both low- and medium-resolution observations. The low-resolution spectroscopic survey acquired 282 exposures ( ≈ 46.6 h) over 25 nights, yielding a total of about 767 000 spectra, and the medium-resolution survey took 177 exposures ( ≈ 49.1…
Membership Lists for 431 Open Clusters in Gaia DR2 Using Extreme Deconvolution Gaussian Mixture Models
Jaehnig, Karl; Holley-Bockelmann, Kelly; Bird, Jonathan
Open clusters are groups of stars that form at the same time, making them an ideal laboratory to test theories of star formation, stellar evolution, and dynamics in the Milky Way disk. However, the utility of an open cluster can be limited by the accuracy and completeness of its known members. Here, we employ a "top-down" technique, Extreme Deconv…
Local stellar kinematics and Oort constants from the LAMOST A-type stars
Wang, H. -F.; Huang, Y.; Chen, B. -Q. +3 more
We estimate the solar peculiar velocities and Oort constants using a sample of 5627 A-type stars with $d\lt 0.6\, \rm kpc$ and $|z|\lt 0.1\, \rm kpc$, selected from the LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope) surveys. The radial and tangential velocities of these A-type stars are fitted by using a non-axisymmetric model.…
Detection of complex organic molecules in young starless core L1521E
Vasyunin, Anton; Launhardt, Ralf; Shirley, Yancy +1 more
Determining the level of chemical complexity within dense starless and gravitationally bound pre-stellar cores is crucial for constructing chemical models, which subsequently constrain the initial chemical conditions of star formation. We have searched for complex organic molecules (COMs) in the young starless core L1521E, and report the first cle…
Star formation history of the solar neighbourhood as told by Gaia
Alzate, Jairo A.; Bruzual, Gustavo; Díaz-González, Daniel J.
The Gaia data release 2 (DR2) catalogue is the best source of stellar astrometric and photometric data available today. The history of the Milky Way galaxy is written in stone in this data set. Parallaxes and photometry tell us where the stars are today, when were they formed, and with what chemical content, that is, their star formation history (…
High-resolution spectroscopic follow-up of the most metal-poor candidates from SkyMapper DR1.1
Schmidt, B. P.; Da Costa, G. S.; Marino, A. F. +13 more
We present chemical abundances for 21 elements (from Li to Eu) in 150 metal-poor Galactic stars spanning -4.1 < [Fe/H] < -2.1. The targets were selected from the SkyMapper survey and include 90 objects with [Fe/H] ≤ -3 of which some 15 have [Fe/H] ≤ -3.5. When combining the sample with our previous studies, we find that the metallicity distr…
Kinematics of the Circumgalactic Medium of a z = 0.77 Galaxy from Mg II Tomography
Faucher-Giguère, Claude-André; Sanders, Ryan L.; Stark, Daniel P. +5 more
Galaxy evolution is thought to be driven in large part by the flow of gas between galaxies and the circumgalactic medium (CGM), a halo of metal-enriched gas extending out to ≳100 kpc from each galaxy. Studying the spatial structure of the CGM holds promise for understanding these gas flow mechanisms; however, the common method of using background …
Gaia Gaps and the Physics of Low-mass Stars. I. The Fully Convective Boundary
Jao, Wei-Chun; Feiden, Gregory A.; Skidmore, Khian
The Gaia M-dwarf gap is a significant underdensity of stars observed near MG = 10.2 in a color-magnitude diagram for stars within 200 pc of the Sun. It has been proposed that the gap is the manifestation of structural instabilities within stellar interiors due to nonequilibrium 3He fusion prior to some stars becoming fully co…
A Model for the Coupled Eruption of a Pseudostreamer and Helmet Streamer
Lynch, B. J.; Antiochos, S. K.; Kumar, P. +3 more
A highly important aspect of solar activity is the coupling between eruptions and the surrounding coronal magnetic field topology, which determines the trajectory and morphology of the event and can even lead to sympathetic eruptions from multiple sources. In this paper, we report on a numerical simulation of a new type of coupled eruption, in whi…