Guy S. Stringfellow
A5030879214- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Atmospheric Ozone and Climate
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- SAS software applications and methods
- Spectroscopy and Laser Applications
- Solar and Space Plasma Dynamics
- Molecular Spectroscopy and Structure
- Nuclear Physics and Applications
- Scientific Measurement and Uncertainty Evaluation
- Adaptive optics and wavefront sensing
- High-pressure geophysics and materials
- Space Exploration and Technology
- Particle Accelerators and Free-Electron Lasers
- Calibration and Measurement Techniques
- Atomic and Molecular Physics
- Scientific Research and Discoveries
University of Colorado Boulder
2012-2024
Laboratory for Atmospheric and Space Physics
2015-2024
CASA
2023-2024
Campbell Collaboration
2021-2023
University of Colorado System
1996-2019
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Association of Universities For Research In Astronomy
2014
University of Washington
2009
Carnegie Institution for Science
2009
Abstract The spectral analysis and data products in Data Release 16 (DR16; 2019 December) from the high-resolution near-infrared Apache Point Observatory Galactic Evolution Experiment (APOGEE)-2/Sloan Digital Sky Survey (SDSS)-IV survey are described. Compared to previous APOGEE release (DR14; 2017 July), DR16 includes about 200,000 new stellar spectra, of which 100,000 a southern instrument mounted on 2.5 m du Pont telescope at Las Campanas Chile. all taken up 2018 August, including...
Thermal images of cold dust in the Central Molecular Zone Milky Way, obtained with far-infrared cameras on board Herschel satellite, reveal a ∼3 × 107 M☉ ring dense and clouds orbiting Galactic center. Using simple toy model, an elliptical shape having semi-major axes 100 60 pc is deduced. The major axis this inclined by about 40° respect to plane sky oriented perpendicular Bar. appears trace system stable x2 orbits predicted for barred potential. Sgr A⋆ displaced geometrical center symmetry...
Abstract The data and analysis methodology used for the SDSS/APOGEE Data Releases 13 14 are described, highlighting differences from DR12 presented in Holtzman et al. Some improvement handling of telluric absorption persistence is demonstrated. derivation calibration stellar parameters, chemical abundances, respective uncertainties along with ranges over which was performed. known issues public related to effective temperatures (DR13), surface gravity (DR13 DR14), C N abundances dwarfs DR14)...
Abstract APOGEE-2 is a high-resolution, near-infrared spectroscopic survey observing ∼3 × 10 5 stars across the entire sky. It successor to APOGEE and part of Sloan Digital Sky Survey IV (SDSS-IV). expanding on APOGEE’s goals addressing critical questions stellar astrophysics, populations, Galactic chemodynamical evolution using (1) an enhanced set target types (2) second spectrograph at Las Campanas Observatory in Chile. targeting red giant branch clump stars, RR Lyrae, low-mass dwarf young...
The double explosion of SN 2009ip in 2012 raises questions about our understanding the late stages massive star evolution. Here we present a comprehensive study during its remarkable rebrightenings. High-cadence photometric and spectroscopic observations from GeV to radio band obtained variety ground-based space facilities (including Very Large Array, Swift, Fermi, Hubble Space Telescope, XMM) constrain be low energy (E ∼ 1050 erg for an ejecta mass ∼0.5 M☉) asymmetric complex medium shaped...
We combine high-resolution spectroscopic data from APOGEE-2 Survey Data Release 16 (DR16) with broad-band photometric several sources, as well parallaxes {\it Gaia} 2 (DR2). Using the Bayesian isochrone-fitting code {\tt StarHorse}, we derive distances, extinctions and astrophysical parameters for around 388,815 APOGEE stars, achieving typical distance uncertainties of $\sim 6\%$ giants, 2\%$ dwarfs, extinction 0.07$ mag when all information is available, 0.17$ if optical photometry missing....
Abstract The updated H -band spectral-line list (from λ 15000–17000) adopted by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) for SDSS-IV Data Release 16 (DR16) is presented in this work. APOGEE line a combination of atomic and molecular lines, with data drawn from laboratory, theoretical, astrophysical sources. Oscillator strengths damping constants are adjusted using high signal-to-noise, high-resolution spectra Sun, α Boo (Arcturus), as “standard stars.” Updates to...
ABSTRACT The current and next observation seasons will detect hundreds of gravitational waves (GWs) from compact binary systems coalescence at cosmological distances. When combined with independent electromagnetic measurements, the source redshift be known, we able to obtain precise measurements Hubble constant H0 via distance–redshift relation. However, most observed mergers are not expected have counterparts, which prevents a direct measurement. In this scenario, one possibility is use...
Abstract We report the discovery and spectroscopic confirmation of an ultra-faint Milky Way satellite in constellation Leo. This system was discovered as a spatial overdensity resolved stars observed with Dark Energy Camera (DECam) data from early version third release DECam Local Volume Exploration (or DELVE) survey. The low luminosity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mi>V</mml:mi>...
We present the Bolocam Galactic Plane Survey (BGPS), a 1.1 mm continuum survey at 33 effective resolution of 170 square degrees visible from northern hemisphere.The BGPS is one first large area, systematic surveys in millimeter without
Type Ia supernovae are key tools for measuring distances on a cosmic scale. They generally thought to be the thermonuclear explosion of an accreting white dwarf in close binary system. The nature mass donor is still uncertain. In single-degenerate model it main-sequence star or evolved star, whereas double-degenerate another dwarf. We show that velocity structure absorbing material along line sight 35 type tends blueshifted. These structures likely signatures gas outflows from supernova...
We present extensive early photometric (ultraviolet through near-infrared) and spectroscopic (optical data on supernova (SN) 2008D as well X-ray analysis the associated Swift transient (XRT) 080109. Our span a time range of 5 hr before detection to 150 days after its detection, detailed allowed us derive constraints nature SN progenitor; throughout we draw comparisons with results presented in literature find several key aspects that differ. show spectrum XRT 080109 can be fit equally by an...
We present a catalog of 8358 sources extracted from images produced by the Bolocam Galactic Plane Survey (BGPS). The BGPS is survey millimeter dust continuum emission northern plane. are using custom algorithm, Bolocat, which was designed specifically to identify and characterize objects in large-area maps generated instrument. products facilitate follow-up observations these relatively unstudied objects. 98% complete 0.4 Jy 60 over all object sizes for sensitive (<35). find that can best be...
Analytical fits to the one-component plasma (OCP) equation of state have been derived for internal energies that reduced all N-dependent effects within statistical uncertainties introduced by Monte Carlo computational process, which themselves are very small. Values N\ensuremath{\gtrsim}500 adequately represent thermodynamic limit. Using fluid only N=686, various analytical generated, compared, and discussed. The thermal energy is accurately represented a simple power-series fit with leading...
We present an analysis of spectrosopic and astrometric data from APOGEE-2 Gaia DR2 to identify structures towards the Orion Complex. By applying a hierarchical clustering algorithm 6-dimensional stellar data, we spatially and/or kinematically distinct groups young objects with ages ranging 1 12 Myr. also investigate star forming history within Complex, peculiar sub-clusters. With this method reconstruct older populations in regions that are presently largely devoid molecular gas, such as C...
Abstract We use the multi-epoch radial velocities acquired by Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey to perform a large-scale statistical study of stellar multiplicity for field stars in Milky Way, spanning evolutionary phases between main sequence (MS) and red clump. show that distribution maximum velocity shifts (ΔRV max ) APOGEE targets is strong function log g , with MS showing ΔRV as high ∼300 <?CDATA $\mathrm{km}\,{{\rm{s}}}^{-1}$?> steadily dropping...
ABSTRACT We investigate the Fe, C, N, O, Mg, Al, Si, K, Ca, Ce, and Nd abundances of 2283 red giant stars in 31 globular clusters from high-resolution spectra observed both Northern Southern hemisphere by SDSS-IV APOGEE-2 survey. This unprecedented homogeneous data set, largest to date, allows us discuss intrinsic Fe spread, shape, statistics Al-Mg N-C anti-correlations as a function cluster mass, luminosity, age, metallicity for all clusters. find that spread does not depend on these...
We report the discovery of two ultra-faint satellites in vicinity Large Magellanic Cloud (LMC) data from Satellites Survey (MagLiteS). Situated 18$^{\circ}$ ($\sim 20$ kpc) LMC and separated each other by only $18^\prime$, Carina~II III form an intriguing pair. By simultaneously modeling spatial color-magnitude stellar distributions, we find that both Carina~III are likely dwarf galaxies, although this is less clear for Carina~III. There fact several obvious differences between satellites....
We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within data from ongoing Survey Magellanic Stellar History conducted with Dark Energy Camera on Blanco 4 m Telescope. The satellite is compact ( ± 11 pc) and faint 0.3), but well realm galaxies. stellar distribution II in color–magnitude diagram well-described by metal-poor () old (13 Gyr) isochrone shows distinct blue horizontal branch, some possible red clump stars, stars that are suggestive stragglers. At...
We present a catalog of stellar properties for large sample 6676 evolved stars with APOGEE spectroscopic parameters and \textit{Kepler} asteroseismic data analyzed using five independent techniques. Our includes evolutionary state, surface gravity, mean density, mass, radius, age, the measurements used to derive them. employ new empirical approach combining from different methods, calibrating inferred parameters, estimating uncertainties. With high statistical significance, we find that...
Multiplicity is a fundamental property that set early during stellar lifetimes, and it stringent probe of the physics star formation. The distribution close companions around young stars still poorly constrained by observations. We present an analysis multiplicity derived from APOGEE-2 spectra obtained in targeted observations nearby star-forming regions. This largest homogeneously observed sample high-resolution stars. developed autonomous method to identify double lined spectroscopic...
We present a re-reduction and expansion of the Bolocam Galactic Plane Survey, first presented by Aguirre et al. (2011) Rosolowsky (2010). The BGPS is 1.1 mm survey dust emission in Northern galactic plane, covering longitudes -10 < \ell 90 latitudes |b| 0.5 with typical 1-\sigma RMS sensitivity 30-100 mJy 33" beam. Version 2 includes an additional 20 square degrees coverage 3rd 4th quadrants 1st quadrant. new data release has improved angular recovery, complete recovery out to 80" partial...
We report the first APOGEE metallicities and alpha-element abundances measured for 3600 red giant stars spanning a large radial range of both Large (LMC) Small Magellanic Clouds (SMC), largest Milky Way dwarf galaxies. Our sample is an order magnitude larger than that previous studies, extends to much distances. These are results presented make use newly installed Southern instrument on du Pont telescope at Las Campanas Observatory. unbiased LMC spans in metallicity, from [Fe/H]=-0.2 very...
Abstract In the updated APOGEE- Kepler catalog, we have asteroseismic and spectroscopic data for over 3000 first ascent red giants. Given size accuracy of this sample, these offer an unprecedented test stellar models on post-main-sequence. When compare to theoretical predictions, find a metallicity dependent temperature offset with slope around 100 K per dex in metallicity. We that effect is present all model grids tested, uncertainties models, correlated errors, shifts mass scale are...
The SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey has obtained high-resolution spectra for thousands of red giant stars distributed among the massive satellite galaxies Milky Way (MW): Large and Small Magellanic Clouds (LMC/SMC), Sagittarius Dwarf (Sgr), Fornax (Fnx), now fully disrupted \emph{Gaia} Sausage/Enceladus (GSE) system. We present analyze APOGEE chemical abundance patterns each galaxy to draw robust conclusions about their star formation histories,...