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Mapping the Galactic Halo. VI. Spectroscopic Measures of Luminosity and Metallicity

Morrison, Heather; Norris, John; Mateo, Mario; Harding, Paul; Olszewski, Edward W; Shectman, Stephen; Dohm-Palmer, Robbie C; Helmi, Amina; Freeman, Kenneth

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We present our calibration of spectroscopic measures of luminosity and metallicity for halo giant candidates and give metallicities and distances for our first sample of spectroscopically confirmed giants. These giants have distances ranging from 15 to 83 kpc. As surveys reach farther into the Galaxy's halo with K giant samples, identification of giants becomes more difficult. This is because the numbers of foreground halo K dwarfs rise for V magnitudes of 19-20, typical for halo giants at ∼...[Show more]

dc.contributor.authorMorrison, Heather
dc.contributor.authorNorris, John
dc.contributor.authorMateo, Mario
dc.contributor.authorHarding, Paul
dc.contributor.authorOlszewski, Edward W
dc.contributor.authorShectman, Stephen
dc.contributor.authorDohm-Palmer, Robbie C
dc.contributor.authorHelmi, Amina
dc.contributor.authorFreeman, Kenneth
dc.date.accessioned2015-12-13T23:09:37Z
dc.identifier.issn0004-6256
dc.identifier.urihttp://hdl.handle.net/1885/87084
dc.description.abstractWe present our calibration of spectroscopic measures of luminosity and metallicity for halo giant candidates and give metallicities and distances for our first sample of spectroscopically confirmed giants. These giants have distances ranging from 15 to 83 kpc. As surveys reach farther into the Galaxy's halo with K giant samples, identification of giants becomes more difficult. This is because the numbers of foreground halo K dwarfs rise for V magnitudes of 19-20, typical for halo giants at ∼ 100 kpc. Our photometric survey uses the strength of the Mg b/H feature near 5170 Å to weed K dwarfs out of the disk and thick disk, but we need spectroscopic measures of the strength of the Ca II K, Ca I λ4227, and Mg b/H features to distinguish between the very metal-poor dwarfs and halo giants. Using a full error analysis of our spectroscopic measures, we show why a signal-to-noise ratio of ∼15 pixel-1 at Ca I λ4227 and ∼10 at Ca II K is needed for reliable luminosity discrimination. We use the Ca II K and Mg b features to measure metallicity in our halo giants, with typical errors (random plus systematic) of 0.3 dex for [Fe/H] values from -0.8 to -3.0.
dc.publisherUniversity of Chicago Press
dc.sourceAstronomical Journal
dc.subjectKeywords: Galaxy: evolution; Galaxy: halo; Galaxy: kinematics and dynamics
dc.titleMapping the Galactic Halo. VI. Spectroscopic Measures of Luminosity and Metallicity
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume125
dc.date.issued2003
local.identifier.absfor020110 - Stellar Astronomy and Planetary Systems
local.identifier.ariespublicationMigratedxPub16221
local.type.statusPublished Version
local.contributor.affiliationMorrison, Heather, Case Western Reserve University
local.contributor.affiliationNorris, John, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationMateo, Mario, University of Michigan
local.contributor.affiliationHarding, Paul, Case Western Reserve University
local.contributor.affiliationOlszewski, Edward W, University of Arizona
local.contributor.affiliationShectman, Stephen, Observatories of the Carnegie Institution of Washington
local.contributor.affiliationDohm-Palmer, Robbie C, University of Michigan
local.contributor.affiliationHelmi, Amina, University of Groningen
local.contributor.affiliationFreeman, Kenneth, College of Physical and Mathematical Sciences, ANU
local.description.embargo2037-12-31
local.bibliographicCitation.startpage2502
local.bibliographicCitation.lastpage2520
local.identifier.doi10.1086/374231
dc.date.updated2015-12-12T08:20:01Z
local.identifier.scopusID2-s2.0-0042260945
CollectionsANU Research Publications

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