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Mapping the Galactic Halo. IV. Finding Distant Giants Reliably with the Washington System

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

Description

We critically examine the use of the Washington photometric system (with the DDO51 filter) for identifying distant halo giants. While this is the most powerful photometric technique for isolating G and K giant stars, spectroscopic follow-up of giant candidates is vital. There are two situations in which interlopers outnumber genuine giants in the diagnostic M - 51/M -T2 plot and are indistinguishable photometrically from the giants. (1) In deep surveys covering tens of square degrees, very...[Show more]

dc.contributor.authorMorrison, Heather
dc.contributor.authorOlszewski, Edward W
dc.contributor.authorMateo, Mario
dc.contributor.authorNorris, John
dc.contributor.authorHarding, Paul
dc.contributor.authorDohm-Palmer, Robbie C
dc.contributor.authorFreeman, Kenneth
dc.date.accessioned2015-12-13T23:41:10Z
dc.date.available2015-12-13T23:41:10Z
dc.identifier.issn0004-6256
dc.identifier.urihttp://hdl.handle.net/1885/94779
dc.description.abstractWe critically examine the use of the Washington photometric system (with the DDO51 filter) for identifying distant halo giants. While this is the most powerful photometric technique for isolating G and K giant stars, spectroscopic follow-up of giant candidates is vital. There are two situations in which interlopers outnumber genuine giants in the diagnostic M - 51/M -T2 plot and are indistinguishable photometrically from the giants. (1) In deep surveys covering tens of square degrees, very metal-poor halo dwarfs are a significant contaminant. An example is our survey of the outer halo, where these metal-poor dwarfs dominate the number of photometric giant candidates at magnitudes fainter than V = 18 and cannot be isolated photometrically. (2) In deep surveys of smaller areas with low photometric precision, most objects in i:he giant region of the color-color plot are dwarfs whose photometric errors have moved them there. Color errors in M - 51 and M - T2 need to be smaller than 0.03 mag to avoid this problem. An example of a survey whose photometric errors place the giant identifications under question is the survey for extratidal giants around the Carina dwarf spheroidal galaxy of Majewski et al. Accurate photometry and spectroscopic follow-up of giant candidates are essential when using the Washington system to identify the rare outer halo giants.
dc.publisherUniversity of Chicago Press
dc.sourceAstronomical Journal
dc.subjectKeywords: Galaxy: Halo; Galaxy: Stellar content; Galaxy: Structure; Techniques: Photometric
dc.titleMapping the Galactic Halo. IV. Finding Distant Giants Reliably with the Washington System
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume121
dc.date.issued2001
local.identifier.absfor020110 - Stellar Astronomy and Planetary Systems
local.identifier.ariespublicationMigratedxPub24454
local.type.statusPublished Version
local.contributor.affiliationMorrison, Heather, Case Western Reserve University
local.contributor.affiliationOlszewski, Edward W, University of Arizona
local.contributor.affiliationMateo, Mario, University of Michigan
local.contributor.affiliationNorris, John, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationHarding, Paul, Case Western Reserve University
local.contributor.affiliationDohm-Palmer, Robbie C, University of Michigan
local.contributor.affiliationFreeman, Kenneth, College of Physical and Mathematical Sciences, ANU
local.bibliographicCitation.startpage283
local.bibliographicCitation.lastpage294
dc.date.updated2015-12-12T09:31:33Z
local.identifier.scopusID2-s2.0-0007432394
CollectionsANU Research Publications

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