125 research outputs found
Prodigious polyphyly in Pleuroceridae (Gastropoda: Cerithioidea)
Phylogenomic studies with hundreds or thousands of loci are rare for most invertebrate groups, including freshwater gastropods. This can prevent understanding of phylogeny, which hinders many areas of research. Pleuroceridae is a family of freshwater snails that is highly imperiled and plays an essential role in the ecology of many freshwater systems of the eastern United States. However, the evolutionary history of the family is not understood, and the systematics of the family has not been revised in a modern framework. Pleurocerids display a variety of egg-deposition behaviors and shell shapes, making the family an ideal system for studying evolution of invertebrate life history and morphology. However, past mitochondrial-based phylogenetic analyses have failed to produce meaningful phylogenetic hypotheses, preventing conclusions about pleurocerid systematics and evolution. Here, we generated a novel anchored hybrid enrichment probe set with phylogenetic utility for Pleuroceridae. We sampled pleurocerids from across their range to test the probe set and generated a backbone phylogeny. Our analyses uncovered striking levels of polyphyly among currently accepted genera. Numerous species were also polyphyletic, indicative of unrecognized diversity. Phylogenetic patterns also revealed considerable convergence of shell morphologies. In contrast, anatomical and life history features appeared to be much less homoplastic. Despite generic paraphyly, high support for most major clades and phylogenetic cohesiveness of non-shell characters indicate utility of the AHE probe set for studying pleurocerid evolution
Final Targeting Strategy for the SDSS-IV APOGEE-2N Survey
APOGEE-2 is a dual-hemisphere, near-infrared (NIR), spectroscopic survey with
the goal of producing a chemo-dynamical mapping of the Milky Way Galaxy. The
targeting for APOGEE-2 is complex and has evolved with time. In this paper, we
present the updates and additions to the initial targeting strategy for
APOGEE-2N presented in Zasowski et al. (2017). These modifications come in two
implementation modes: (i) "Ancillary Science Programs" competitively awarded to
SDSS-IV PIs through proposal calls in 2015 and 2017 for the pursuit of new
scientific avenues outside the main survey, and (ii) an effective 1.5-year
expansion of the survey, known as the Bright Time Extension, made possible
through accrued efficiency gains over the first years of the APOGEE-2N project.
For the 23 distinct ancillary programs, we provide descriptions of the
scientific aims, target selection, and how to identify these targets within the
APOGEE-2 sample. The Bright Time Extension permitted changes to the main survey
strategy, the inclusion of new programs in response to scientific discoveries
or to exploit major new datasets not available at the outset of the survey
design, and expansions of existing programs to enhance their scientific success
and reach. After describing the motivations, implementation, and assessment of
these programs, we also leave a summary of lessons learned from nearly a decade
of APOGEE-1 and APOGEE-2 survey operations. A companion paper, Santana et al.
(submitted), provides a complementary presentation of targeting modifications
relevant to APOGEE-2 operations in the Southern Hemisphere.Comment: 59 pages; 11 Figures; 7 Tables; 2 Appendices; Submitted to Journal
and Under Review; Posting to accompany papers using the SDSS-IV/APOGEE-2 Data
Release 17 scheduled for December 202
Measurement of the tau lepton lifetime
The mean lifetime of the tau lepton is measured in a sample of 25700 tau pairs collected in 1992 with the ALEPH detector at LEP. A new analysis of the 1-1 topology events is introduced. In this analysis, the dependence of the impact parameter sum distribution on the daughter track momenta is taken into account, yielding improved precision compared to other impact parameter sum methods. Three other analyses of the one- and three-prong tau decays are updated with increased statistics. The measured lifetime is 293.5+/-3.1+/-1.7 fs. Including previous (1989-1991) ALEPH measurements, the combined tau lifetime is 293.7+/-2.7+/-1.6 fs
The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2,MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA,the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions ofthe SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1data from SDSS-III, with abundances of elements not previously included and improved stellar parameters for dwarf stars and cooler stars. For the SDSS imaging data, DR13 provides new, more robust and precise photometric calibrations. Several value-added catalogs are being released in tandem with DR13, in particular target catalogs relevant for eBOSS, TDSS, and SPIDERS, and an updated red-clump catalog for APOGEE.This paper describes the location and format of the data now publicly available, as well as providing references to the important technical papers that describe the targeting, observing, and data reduction. The SDSS website, http://www.sdss.org, provides links to the data, tutorials and examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6-year operations of SDSS-IV.PostprintPeer reviewe
Sloan Digital Sky Survey IV: mapping the Milky Way, nearby galaxies, and the distant universe
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median ). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July
The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17)
Recommended from our members
The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17)
Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median ). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July
The 16th Data Release of the Sloan Digital Sky Surveys : First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).Peer reviewe
SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II),
SDSS-III is a program of four spectroscopic surveys on three scientific themes:
dark energy and cosmological parameters, the history and structure of the Milky
Way, and the population of giant planets around other stars. In keeping with
SDSS tradition, SDSS-III will provide regular public releases of all its data,
beginning with SDSS DR8 (which occurred in Jan 2011). This paper presents an
overview of the four SDSS-III surveys. BOSS will measure redshifts of 1.5
million massive galaxies and Lya forest spectra of 150,000 quasars, using the
BAO feature of large scale structure to obtain percent-level determinations of
the distance scale and Hubble expansion rate at z<0.7 and at z~2.5. SEGUE-2,
which is now completed, measured medium-resolution (R=1800) optical spectra of
118,000 stars in a variety of target categories, probing chemical evolution,
stellar kinematics and substructure, and the mass profile of the dark matter
halo from the solar neighborhood to distances of 100 kpc. APOGEE will obtain
high-resolution (R~30,000), high signal-to-noise (S/N>100 per resolution
element), H-band (1.51-1.70 micron) spectra of 10^5 evolved, late-type stars,
measuring separate abundances for ~15 elements per star and creating the first
high-precision spectroscopic survey of all Galactic stellar populations (bulge,
bar, disks, halo) with a uniform set of stellar tracers and spectral
diagnostics. MARVELS will monitor radial velocities of more than 8000 FGK stars
with the sensitivity and cadence (10-40 m/s, ~24 visits per star) needed to
detect giant planets with periods up to two years, providing an unprecedented
data set for understanding the formation and dynamical evolution of giant
planet systems. (Abridged)Comment: Revised to version published in The Astronomical Journa
- …