English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present an improved analysis of halo substructure traced by RR Lyrae starsin the SDSS stripe 82 region. With the addition of SDSS-II data, a revisedselection method based on new ugriz light curve templates results in a sampleof 483 RR Lyrae stars that is essentially free of contamination. The mainresult from our first study persists: the spatial distribution of halo stars atgalactocentric distances 5--100 kpc is highly inhomogeneous. At least 20% ofhalo stars within 30 kpc from the Galactic center can be statisticallyassociated with substructure. We present strong direct evidence, based on bothRR Lyrae stars and main sequence stars, that the halo stellar number densityprofile significantly steepens beyond a Galactocentric distance of ~30 kpc, anda larger fraction of the stars are associated with substructure. By using anovel method that simultaneously combines data for RR Lyrae and main sequencestars, and using photometric metallicity estimates for main sequence starsderived from deep co-added u-band data, we measure the metallicity of theSagittarius dSph tidal stream (trailing arm) towards R.A.2h-3h and Dec~0 deg tobe 0.3 dex higher ([Fe/H]=-1.2) than that of surrounding halo field stars.Together with a similar result for another major halo substructure, theMonoceros stream, these results support theoretical predictions that an earlyforming, smooth inner halo, is metal poor compared to high surface brightnessmaterial that have been accreted onto a later-forming outer halo. The meanmetallicity of stars in the outer halo that are not associated with detectableclumps may still be more metal-poor than the bulk of inner-halo stars, as hasbeen argued from other data sets.

Light Curve Templates and Galactic Distribution of RR Lyrae Stars from Sloan Digital Sky Survey Stripe 82