The QUEST RR Lyrae Survey: Confirmation of the Clump at 50 kpc and Other Over-Densities in the Outer Halo

A. K. Vivas; R. Zinn; P. Andrews; C. Bailyn; C. Baltay; P. Coppi; N. Ellman; T. Girard; D. Rabinowitz; B. Schaefer; J. Shin; J. Snyder; S. Sofia; W. van Altena; C. Abad; A. Bongiovanni; C. Briceno; G. Bruzual; F. Della Prugna; D. Herrera; G. Magris; J. Mateu; R. Pacheco; Ge. Sanchez; Gu. Sanchez; H. Schenner; J. Stock; B. Vicente; K. Vieira; I. Ferrin; J. Hernandez; M. Gebhard; R. Honeycutt; s. Muffson; J. Musser; A. Rengstorf

doi:10.1086/320915

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The QUEST RR Lyrae Survey: Confirmation of the Clump at 50 kpc and Other Over-Densities in the Outer Halo

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Abstract

We have measured the periods and light curves of 148 RR Lyrae variables from V=13.5 to 19.7 from the first 100 sq. degrees of the QUEST RR Lyrae survey. Approximately 55% of these stars belong to the clump of stars detected earlier by the Sloan Digital Sky Survey. According to our measurements, this feature has ~10 times the background density of halo stars, spans at least 37.5 deg by 3.5 deg in right ascension and declination (>=30 by >=3 kpc), lies ~50 kpc from the Sun, and has a depth along the line of sight of ~5 kpc (1 sigma). These properties are consistent with the recent models that suggest it is a tidal stream from the Sgr dSph galaxy. The mean period of the type ab variables, 0.58 d, is also consistent. In addition, we have found two smaller over-densities in the halo, one of which may be related to the globular cluster Pal 5.

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A. K. Vivas, R. Zinn, P. Andrews, C. Bailyn, C. Baltay, P. Coppi, N. Ellman, T. Girard, D. Rabinowitz, B. Schaefer, J. Shin, J. Snyder, S. Sofia, W. van Altena, C. Abad, A. Bongiovanni, C. Briceno, G. Bruzual, F. Della Prugna, D. Herrera, G. Magris, J. Mateu, R. Pacheco, Ge. Sanchez, Gu. Sanchez, H. Schenner, J. Stock, B. Vicente, K. Vieira, I. Ferrin, J. Hernandez, M. Gebhard, R. Honeycutt, s. Muffson, J. Musser, A. Rengstorf. 2001-05-08. The QUEST RR Lyrae Survey: Confirmation of the Clump at 50 kpc and Other Over-Densities in the Outer Halo. https://doi.org/10.1086/320915

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