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Title: Milky Way tomography with K and M dwarf stars: The vertical structure of the galactic disk

Abstract

Here, 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 (SDSS), 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 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 sensitivemore » to the selected latitude window. We explain why this may be indicative of a change in stellar populations in the compared latitude regions, possibly allowing access to the systematic metallicity difference between thin and thick disk populations through photometry.« less

Authors:
 [1];  [2];  [3]
  1. Univ. of Kentucky, Lexington, KY (United States)
  2. Univ. of Kentucky, Lexington, KY (United States); Univ. of California, Irvine, CA (United States)
  3. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1365572
Report Number(s):
FERMILAB-PUB-17-187-AE
Journal ID: ISSN 1538-4357; 1607147
Grant/Contract Number:
AC02-07CH11359
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 843; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxies: structure; galaxies: evolution

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. 2017. "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_1365572,
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 = {Here, 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 (SDSS), 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 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 compared latitude regions, possibly allowing access to the systematic metallicity difference between thin and thick disk populations through photometry.},
doi = {10.3847/1538-4357/aa77fd},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 843,
place = {United States},
year = 2017,
month = 6
}

Journal Article:
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