David L. Nidever
A5014732953- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Scientific Research and Discoveries
- Spectroscopy and Laser Applications
- Spacecraft and Cryogenic Technologies
- Calibration and Measurement Techniques
- Historical Astronomy and Related Studies
- Methane Hydrates and Related Phenomena
- Spectroscopy and Chemometric Analyses
- Atmospheric Ozone and Climate
- Isotope Analysis in Ecology
- Maritime and Coastal Archaeology
- Satellite Image Processing and Photogrammetry
- Environmental Monitoring and Data Management
- Radio Astronomy Observations and Technology
Montana State University
2018-2024
National Solar Observatory
2024
NSF’s NOIRLab
2019-2024
Flatiron Institute
2024
Flatiron Health (United States)
2024
Campbell Collaboration
2023
Kitt Peak National Observatory
2016-2020
Community Science and Data Center
2020
Optica
2016-2019
NOAA National Data Buoy Center
2019
Abstract Multi-epoch radial velocity measurements of stars can be used to identify stellar, substellar, and planetary-mass companions. Even a small number observation epochs informative about companions, though there multiple qualitatively different orbital solutions that fit the data. We have custom-built Monte Carlo sampler ( The Joker ) delivers reliable (and often highly multimodal) posterior samplings for companion parameters given sparse Here we use perform search companions 96,231 red...
The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the programs in Sloan Digital Sky Survey III (SDSS-III), has now completed its systematic, homogeneous spectroscopic survey sampling all major populations Milky Way. After a three year observing campaign on 2.5-m Telescope, APOGEE collected half million high resolution (R~22,500), S/N (>100), infrared (1.51-1.70 microns) spectra for 146,000 stars, with time series information via repeat visits to most these stars....
We report radial velocities for 844 FGKM-type main sequence and subgiant stars 45 K giants, most of which had either low-precision velocity measurements or none at all. These differ from the standard Udry et al. by 0.035 km/s (RMS) 26 FGK in common. The zero-point our differs that al.: (V_present - V_Udry) = +0.053 km/s. Thus these new agree with best known both precision zero-point, to well within 0.1 Nonetheless, standards suffer three sources systematic error, namely, convective...
Using a sample of 69,919 red giants from the SDSS-III/APOGEE Data Release 12, we measure distribution stars in [α/Fe] versus [Fe/H] plane and metallicity functions (MDFs) across an unprecedented volume Milky Way disk, with radius 3 < R 15 kpc height kpc. Stars inner disk (R 5 kpc) lie along single track [Fe/H], starting α-enhanced, metal-poor ending at ∼ 0 +0.4. At larger radii find two distinct sequences space, roughly solar-α sequence that spans decade high-α merges low-α super-solar...
We measure the Milky Way's rotation curve over Galactocentric range 4 kpc ≲ R 14 from first year of data Apache Point Observatory Galactic Evolution Experiment. model line-of-sight velocities 3365 stars in fields with b = 0° between 30° ⩽ l 210° out to distances 10 using an axisymmetric kinematical that includes a correction for asymmetric drift warm tracer population (σR ≈ 35 km s−1). determine local value circular velocity be Vc(R0) 218 ± 6 s−1 and find is approximately flat derivative...
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has built the largest moderately high-resolution (R=22, 500) spectroscopic map of stars across Milky Way, and including dust-obscured areas. APOGEE Stellar Parameter Chemical Abundances Pipeline (ASPCAP) is software developed for automated analysis these spectra. ASPCAP determines atmospheric parameters chemical abundances from observed spectra by comparing to libraries theoretical spectra, using chi-2 minimization in a...
The SDSS-III/APOGEE survey operated from 2011-2014 using the APOGEE spectrograph, which collects high-resolution (R~22,500), near-IR (1.51-1.70 microns) spectra with a multiplexing (300 fiber-fed objects) capability. We describe data products that are publicly available, include catalogs radial velocity, stellar parameters, and 15 elemental abundances for over 150,000 stars, as well more than 500,000 these quantities derived. Calibration relations parameters (Teff, log g, [M/H], [alpha/M])...
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a high-resolution infrared spectroscopic survey spanning all environments (i.e., bulge, disk, and halo), with the principal goal of constraining dynamical chemical evolution models Milky Way. APOGEE takes advantage reduced effects extinction at wavelengths to observe inner Galaxy bulge an unprecedented level detail. survey's broad spatial wavelength coverage enables users data address numerous structure stellar...
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...
We describe the design and performance of near-infrared (1.51--1.70 micron), fiber-fed, multi-object (300 fibers), high resolution (R = lambda/delta lambda ~ 22,500) spectrograph built for Apache Point Observatory Galactic Evolution Experiment (APOGEE). APOGEE is a survey 10^5 red giant stars that systematically sampled all Milky Way populations (bulge, disk, halo) to study Galaxy's chemical kinematical history. It was part Sloan Digital Sky Survey III (SDSS-III) from 2011 -- 2014 using 2.5...
The Apache Point Observatory Galactic Evolution Experiment (APOGEE), part of the Sloan Digital Sky Survey III, explores stellar populations Milky Way using 2.5-m telescope linked to a high resolution (R~22,500), near-infrared (1.51-1.70 microns) spectrograph with 300 optical fibers. For over 150,000 predominantly red giant branch stars that APOGEE targeted across bulge, disks and halo, collected S/N (>100 per half-resolution element) spectra provide accurate (~0.1 km/s) radial velocities,...
The spatial structure of stellar populations with different chemical abundances in the Milky Way contains a wealth information on Galactic evolution over cosmic time. We use data 14,699 red-clump stars from APOGEE survey, covering 4 kpc <~ R 15 kpc, to determine mono-abundance (MAPs)---stars narrow bins [a/Fe] and [Fe/H]---accounting for complex effects selection function spatially-variable dust obscuration. that all MAPs enhanced are centrally concentrated well-described as exponentials...
We present the first APOKASC catalog of spectroscopic and asteroseismic properties 1916 red giants observed in Kepler fields. The parameters provided from Apache Point Observatory Galactic Evolution Experiment project are complemented with surface gravities, masses, radii, mean densities determined by members Asteroseismology Science Consortium. assess both random systematic sources error include a discussion sample selection for Total uncertainties main order 80 K Teff , 0.06 dex [M/H],...
We employ the first two years of data from near-infrared, high-resolution SDSS-III/APOGEE spectroscopic survey to investigate distribution metallicity and α-element abundances stars over a large part Milky Way disk. Using sample ≈10, 000 kinematically unbiased red-clump with ∼5% distance accuracy as tracers, [α/Fe] versus [Fe/H] this exhibits bimodality in at intermediate metallicities, −0.9 < <−0.2, but higher metallicities ([Fe/H] ∼+0.2) sequences smoothly merge. effects APOGEE selection...
Formation of globular clusters (GCs), the Galactic bulge, or galaxy bulges in general, are important unsolved problems astronomy. Homogeneous infrared observations large samples stars belonging to GCs and bulge field one best ways study these problems. We report discovery by APOGEE a population inner Galaxy with abundances N, C, Al that typically found GC stars. The newly discovered have high [N/Fe], which is correlated [Al/Fe] anti-correlated [C/Fe]. They homogeneously distributed across,...
Abstract The kinematics of the Milky Way disc as a function age are well measured at solar radius, but have not been studied over wider range Galactocentric radii. Here, we measure mono-age, mono-[Fe/H] populations in low and high [α/Fe] discs between 4 ≲ R 13 kpc |z| 2 using 65 719 stars common APOGEE DR14 Gaia DR2 for which estimate ages Bayesian neural network model trained on asteroseismic ages. We determine vertical radial velocity dispersions, finding that display markedly different...
The eighteenth data release of the Sloan Digital Sky Surveys (SDSS) is first one for SDSS-V, fifth generation survey. SDSS-V comprises three primary scientific programs, or "Mappers": Milky Way Mapper (MWM), Black Hole (BHM), and Local Volume (LVM). This contains extensive targeting information two multi-object spectroscopy programs (MWM BHM), including input catalogs selection functions their numerous objectives. We describe production databases calibration- scientifically-focused...
Abstract The structure and dynamics of the star-forming disk Small Magellanic Cloud (SMC) have long confounded us. SMC is widely used as a prototype for galactic physics at low metallicity, yet we fundamentally lack an understanding its interstellar medium (ISM). In this work, present new model by comparing kinematics young, massive stars with ISM traced high-resolution observations neutral atomic hydrogen (H i ) from Galactic Australian Square Kilometre Array Pathfinder survey....
Abstract We present the discovery of Aquarius III, an ultra-faint Milky Way satellite galaxy identified in second data release DECam Local Volume Exploration survey. Based on deeper follow-up imaging with DECam, we find that III is a 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> </mml:msub> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:msubsup> <mml:mn>2.5</mml:mn>...
Abstract The existence of high- α stars with inferred ages <6 Gyr has been confirmed recently large spectroscopic and photometric surveys. However, stellar mergers or binary interactions can induce properties associated young ages, such as high mass, rapid rotation, activity, even in old populations. Literature studies have that at least some these apparently are merger products. none ruled out the possibility genuinely stars. Because cool GKM dwarfs spin down, rotation be used to...
We explore the Magellanic Stream (MS) using a Gaussian decomposition of H I velocity profiles in Leiden-Argentine-Bonn (LAB) all-sky survey. This reveals MS to be composed two filaments distinct both spatially (as first pointed out by Putman et al.) and velocity. Using coherence filaments, one can traced back its origin what we identify as southeast overdensity (SEHO) Large Cloud (LMC), which includes 30 Doradus. Parts Leading Arm (LA) also SEHO position. Therefore, at least one-half...
As part of the ACS Survey Galactic Globular Clusters, we present new Hubble Space Telescope photometry massive globular cluster M54 (NGC 6715) and superposed core tidally disrupted Sagittarius (Sgr) dSph galaxy. Our deep (F606W ~ 26.5), high-precision yields an unprecedentedly detailed color-magnitude diagram showing extended blue horizontal branch multiple main sequences M54+Sgr system. The distance reddening to are revised using both isochrone main-sequence fitting (m - M)0 = 17.27 E(B V)...
Context. The Apache Point Observatory Galactic Evolution Experiment (APOGEE) features the first multi-object high-resolution fiber spectrograph in near-infrared ever built, thus making survey unique its capabilities: APOGEE is able to peer through dust that obscures stars disc and bulge optical wavelength range. Here we explore data included as part of Sloan Digital Sky Survey's 10th release (SDSS DR10).
We establish that the Magellanic Stream (MS) is some 40 degrees longer than previously known with certainty and entire MS Leading Arm (LA) system thus at least 200 long. With GBT, we conducted a ~200 square degree, 21-cm survey MS-tip to substantiate continuity of between Hulsbosch & Wakker data MS-like emission reported by Braun Thilker. Our survey, in combination Arecibo Stanimirovic et al., shows gas continuous this region ~140 identify new filament on eastern side significantly...
A new large-area Washington M, T2+DDO51 filter survey of more than 10 deg2 around the Carina dSph galaxy reveals a spectroscopically confirmed power-law radial density "break" population giant stars extending several degrees beyond central King profile. Magellan telescope MIKE spectroscopy establishes existence to at least 4.5 times its limiting radius, rlim, and primarily along Carina's major axis. To keep these bound would require global mass-to-light ratio M/L ≥ 6300 (M/L)☉. The...