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Related papers: Leaves on trees: identifying halo stars with extre…

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Precise abundance ratios are determined for 94 dwarf stars with 5200 < Teff < 6300 K, -1.6 < [Fe/H] < -0.4, and distances D < 335 pc. Most of them have halo kinematics, but 16 thick-disk stars are included. Equivalent widths of atomic lines…

Astrophysics of Galaxies · Physics 2015-05-18 Poul E. Nissen , William J. Schuster

We introduce gbpTrees: an algorithm for constructing merger trees from cosmological simulations, designed to identify and correct for pathological cases introduced by errors or ambiguities in the halo finding process. gbpTrees is built upon…

Astrophysics of Galaxies · Physics 2017-11-08 Gregory B. Poole , Simon J. Mutch , Darren J. Croton , Stuart Wyithe

We study the dynamical properties of halo stars located in the Solar Neighbourhood. Our goal is to explore how the properties of the halo depend on the selection criteria used for defining a sample of halo stars. Once this is understood we…

Astrophysics of Galaxies · Physics 2018-07-18 Lorenzo Posti , Amina Helmi , Jovan Veljanoski , Maarten Breddels

The hierarchical structure formation model predicts that stellar halos should form, at least partly, via mergers. If this was a predominant formation channel for the Milky Way's halo, imprints of this merger history in the form of moving…

Astrophysics of Galaxies · Physics 2017-02-01 Amina Helmi , Jovan Veljanoski , Maarten A. Breddels , Hao Tian , Laura V. Sales

The search for planets orbiting other stars has recently expanded to include stars from galaxies outside the Milky Way. With the TESS and Gaia surveys, photometric and kinematic information can be combined to identify transiting planet…

Earth and Planetary Astrophysics · Physics 2022-09-07 Stephanie Yoshida , Samuel Grunblatt , Adrian Price-Whelan

To extract information from the clustering of galaxies on non-linear scales, we need to model the connection between galaxies and halos accurately and in a flexible manner. Standard halo occupation distribution (HOD) models make the…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-22 Ana Maria Delgado , Digvijay Wadekar , Boryana Hadzhiyska , Sownak Bose , Lars Hernquist , Shirley Ho

Motivated by previous findings that the magnitude gap between certain satellite galaxy and the central galaxy can be used to improve the estimation of halo mass, we carry out a systematic study of the information content of different member…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-30 Yanrui Zhou , Jiaxin Han

When following the growth of structure in the Universe, we propose replacing merger trees with merger graphs, in which haloes can both merge and split into separate pieces. We show that this leads to smoother mass growth and eliminates…

Astrophysics of Galaxies · Physics 2020-05-11 William J. Roper , Peter A. Thomas , Chaichalit Srisawat

This paper reports on the application of the supervised machine-learning algorithm to the stellar effective temperature regression for the second $Gaia$ data release, based on the combination of the stars in four spectroscopic surveys:…

Solar and Stellar Astrophysics · Physics 2019-08-14 Yu Bai , JiFeng Liu , ZhongRui Bai , Song Wang , DongWei Fan

The paucity of hypervelocity stars (HVSs) known to date has severely hampered their potential to investigate the stellar population of the Galactic Centre and the Galactic Potential. The first Gaia data release gives an opportunity to…

Astrophysics of Galaxies · Physics 2017-05-30 T. Marchetti , E. M. Rossi , G. Kordopatis , A. G. A. Brown , A. Rimoldi , E. Starkenburg , K. Youakim , R. Ashley

Ghostly stellar haloes are extended haloes of stars composed solely of debris of pre-reionization fossil galaxies and should exist in dwarf galaxies with total masses $<10^{10}$ M$_\odot$. Fossil galaxies are even smaller mass dwarf…

Astrophysics of Galaxies · Physics 2022-09-07 Massimo Ricotti , Emil Polisensky , Emily Cleland

Precise stellar ages (uncertainties $\lesssim 1$ Gyr, or $\sim 20\%$ at solar age) are required to discern evolutionary trends in atmospheric biosignatures of terrestrial habitable zone exoplanets surveyed by the Habitable Worlds…

Solar and Stellar Astrophysics · Physics 2026-05-14 Austin T. Ware , Katelyn Ruppert , Patrick A. Young

Semi-analytic models are best suited to compare galaxy formation and evolution theories with observations. These models rely heavily on halo merger trees, and their realistic features (i.e., no drastic changes on halo mass or jumps on…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-25 Sandra Robles , Jonathan S. Gómez , Adín Ramírez Rivera , Jenny A. González , Nelson D. Padilla , Diego Dujovne

Marked statistics allow sensitive tests of how galaxy properties correlate with environment, as well as of how correlations between galaxy properties are affected by environment. A halo-model description of marked correlations is developed,…

Astrophysics · Physics 2009-11-16 Ravi K. Sheth

The Gaia satellite will observe the positions and velocities of over a billion Milky Way stars. In the early data releases, the majority of observed stars do not have complete 6D phase-space information. In this Letter, we demonstrate the…

Astrophysics of Galaxies · Physics 2021-07-08 Adriana Dropulic , Bryan Ostdiek , Laura J. Chang , Hongwan Liu , Timothy Cohen , Mariangela Lisanti

We improve the identification and isolation of individual stellar populations in the Galactic halo based on an updated set of empirically calibrated stellar isochrones in the Sloan Digital Sky Survey (SDSS) and Pan-STARRS 1 (PS1)…

Astrophysics of Galaxies · Physics 2021-02-10 Deokkeun An , Timothy C. Beers

Nearby stellar streams carry unique information on the dynamical evolution and disruption of stellar systems in the Galaxy, the mass distribution in the disk, and provide unique targets for planet formation and evolution studies. We revisit…

Astrophysics of Galaxies · Physics 2020-07-08 S. Ratzenböck , S. Meingast , J. Alves , T. Möller , I. Bomze

We present a catalogue of point-like H{\alpha}-excess sources in the Northern Galactic Plane. Our catalogue is created using a new technique that leverages astrometric and photomeric information from Gaia to select H{\alpha}-bright outliers…

Galaxy formation, viewed as an inference problem from incomplete information, is inherently stochastic. Reducing the full simulation state to a coarse-grained set of variables integrates out unresolved degrees of freedom, motivating an…

Astrophysics of Galaxies · Physics 2026-05-29 Daneng Yang

Classifying catalog objects as stars, galaxies, or AGN 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…

Astrophysics of Galaxies · Physics 2021-04-14 Anneya Golob , Marcin Sawicki , Andy D. Goulding , Jean Coupon