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LAMPSS: Discovery of Metal-Poor Stars in the Galactic Halo with the CaHK filter on CFHT MegaCam

Research output: Contribution to journalJournal article

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  • Eleanor Worrell
  • Niam Patel
  • Karolina Wresilo
  • Sam Dicker
  • Olivia Bray
  • Jack Bagness
  • David Sobral
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<mark>Journal publication date</mark>7/06/2019
<mark>Journal</mark>Notices of Lancaster Astrophysics (NLUAstro)
Volume1
Number of pages16
Pages (from-to)75-90
Publication statusPublished
Original languageEnglish

Abstract

We present the Lancaster Astrophysics Metal Poor Star Search (LAMPSS) in the Milky Way halo, conducted using the metallicity-sensitive Ca H & K lines. We use the CaHK filter of the MegaPrime/MegaCam on the Canada-France-Hawaii Telescope (CFHT) to survey an area of 1.010deg2 over the COSMOS field. We combine our new CaHK data with broadband optical and near-infrared photometry of COSMOS to recover stars down to mHK ∼ 26. After removing galaxies, we find 70% completion and 30% contamination for our remaining 1772 stars. By exploring a range of spectral types and metallicities, we derive metallicity-sensitive colour-colour diagrams which we use to isolate different spectral types and metallicities (−5 ≤ [Fe/H ≤ 0). From these, we identify 16 potentially extremely metal-poor stars. One of which, LAMPS 1229, we predict to have [Fe/H] ∼ −5.0 at a distance of (78.21 ± 9.37) kpc. We construct a Metallicity Distribution Function for our sample of metal-poor stars, finding an expected sharp decrease in count as [Fe/H] decreases.

Bibliographic note

Worrell et al. (2019), NLUAstro, 1, 75