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Title: Milky Way Tomography with K and M Dwarf Stars: The Vertical Structure of the Galactic Disk

Abstract

We use the number density distributions of K and M dwarf stars with vertical height from the Galactic disk, determined using observations from the Sloan Digital Sky Survey, to probe the structure of the Milky Way disk across the survey’s footprint. Using photometric parallax as a distance estimator we analyze a sample of several million disk stars in matching footprints above and below the Galactic plane, and we determine the location and extent of vertical asymmetries in the number counts in a variety of thin- and thick-disk subsamples in regions of some 200 square degrees within 2 kpc in vertical distance from the Galactic disk. These disk asymmetries present wave-like features as previously observed on other scales and at other distances from the Sun. We additionally explore the scale height of the disk and the implied offset of the Sun from the Galactic plane at different locations, noting that the scale height of the disk can differ significantly when measured using stars only above or only below the plane. Moreover, we compare the shape of the number density distribution in the north for different latitude ranges with a fixed range in longitude and find the shape to be sensitive tomore » the selected latitude window. We explain why this may be indicative of a change in stellar populations in the latitude regions compared, possibly allowing access to the systematic metallicity difference between thin- and thick-disk populations through photometry.« less

Authors:
;  [1];  [2]
  1. Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States)
  2. Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)
Publication Date:
OSTI Identifier:
22663393
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 843; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; COMPARATIVE EVALUATIONS; DENSITY; DISTRIBUTION; DWARF STARS; METALLICITY; MILKY WAY; PHOTOMETRY; SKY; TOMOGRAPHY

Citation Formats

Ferguson, Deborah, Gardner, Susan, and Yanny, Brian. Milky Way Tomography with K and M Dwarf Stars: The Vertical Structure of the Galactic Disk. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA77FD.
Ferguson, Deborah, Gardner, Susan, & Yanny, Brian. Milky Way Tomography with K and M Dwarf Stars: The Vertical Structure of the Galactic Disk. United States. doi:10.3847/1538-4357/AA77FD.
Ferguson, Deborah, Gardner, Susan, and Yanny, Brian. Mon . "Milky Way Tomography with K and M Dwarf Stars: The Vertical Structure of the Galactic Disk". United States. doi:10.3847/1538-4357/AA77FD.
@article{osti_22663393,
title = {Milky Way Tomography with K and M Dwarf Stars: The Vertical Structure of the Galactic Disk},
author = {Ferguson, Deborah and Gardner, Susan and Yanny, Brian},
abstractNote = {We use the number density distributions of K and M dwarf stars with vertical height from the Galactic disk, determined using observations from the Sloan Digital Sky Survey, to probe the structure of the Milky Way disk across the survey’s footprint. Using photometric parallax as a distance estimator we analyze a sample of several million disk stars in matching footprints above and below the Galactic plane, and we determine the location and extent of vertical asymmetries in the number counts in a variety of thin- and thick-disk subsamples in regions of some 200 square degrees within 2 kpc in vertical distance from the Galactic disk. These disk asymmetries present wave-like features as previously observed on other scales and at other distances from the Sun. We additionally explore the scale height of the disk and the implied offset of the Sun from the Galactic plane at different locations, noting that the scale height of the disk can differ significantly when measured using stars only above or only below the plane. Moreover, we compare the shape of the number density distribution in the north for different latitude ranges with a fixed range in longitude and find the shape to be sensitive to the selected latitude window. We explain why this may be indicative of a change in stellar populations in the latitude regions compared, possibly allowing access to the systematic metallicity difference between thin- and thick-disk populations through photometry.},
doi = {10.3847/1538-4357/AA77FD},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 843,
place = {United States},
year = {2017},
month = {7}
}

Works referencing / citing this record:

A homogeneous sample of 34 000 M7−M9.5 dwarfs brighter than J = 17.5 with accurate spectral types
journal, March 2019