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Title: EVIDENCE FOR A MILKY WAY TIDAL STREAM REACHING BEYOND 100 kpc

Abstract

We present the analysis of 1207 RR Lyrae found in photometry taken by the Catalina Survey's Mount Lemmon telescope. By combining accurate distances for these stars with measurements for {approx}14,000 type-ab RR Lyrae from the Catalina Schmidt telescope, we reveal an extended association that reaches Galactocentric distances beyond 100 kpc and overlaps the Sagittarius stream system. This result confirms earlier evidence for the existence of an outer halo tidal stream resulting from a disrupted stellar system. By comparing the RR Lyrae source density with that expected based on halo models, we find the detection has {approx}8{sigma} significance. We investigate the distances, radial velocities, metallicities, and period-amplitude distribution of the RR Lyrae. We find that both radial velocities and distances are inconsistent with current models of the Sagittarius stream. We also find tentative evidence for a division in source metallicities for the most distant sources. Following prior analyses, we compare the locations and distances of the RR Lyrae with photometrically selected candidate horizontal branch stars and find supporting evidence that this structure spans at least 60 Degree-Sign of the sky. We investigate the prospects of an association between the stream and the unusual globular cluster NGC 2419.

Authors:
; ; ; ; ;  [1]; ;  [2];  [3]; ; ;  [4]
  1. California Institute of Technology, 1200 E. California Blvd., CA 91225 (United States)
  2. Pontificia Universidad Catolica de Chile, Departamento de Astronomia y Astrofisica, Facultad de Fisica, Av. Vicuna Mackena 4860, 782-0436 Macul, Santiago (Chile)
  3. Department of Astronomy, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States)
  4. Department of Planetary Sciences, University of Arizona, Lunar and Planetary Laboratory, 1629 E. University Blvd., Tucson AZ 85721 (United States)
Publication Date:
OSTI Identifier:
22126967
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 765; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; DENSITY; DISTANCE; GALACTIC EVOLUTION; MILKY WAY; PHOTOMETRY; RADIAL VELOCITY; SPATIAL DISTRIBUTION; TELESCOPES; VARIABLE STARS

Citation Formats

Drake, A. J., Djorgovski, S. G., Graham, M. J., Mahabal, A., Donalek, C., Williams, R., Catelan, M., Torrealba, G., Prieto, J. L., Larson, S., Christensen, E., and Beshore, E. EVIDENCE FOR A MILKY WAY TIDAL STREAM REACHING BEYOND 100 kpc. United States: N. p., 2013. Web. doi:10.1088/0004-637X/765/2/154.
Drake, A. J., Djorgovski, S. G., Graham, M. J., Mahabal, A., Donalek, C., Williams, R., Catelan, M., Torrealba, G., Prieto, J. L., Larson, S., Christensen, E., & Beshore, E. EVIDENCE FOR A MILKY WAY TIDAL STREAM REACHING BEYOND 100 kpc. United States. https://doi.org/10.1088/0004-637X/765/2/154
Drake, A. J., Djorgovski, S. G., Graham, M. J., Mahabal, A., Donalek, C., Williams, R., Catelan, M., Torrealba, G., Prieto, J. L., Larson, S., Christensen, E., and Beshore, E. 2013. "EVIDENCE FOR A MILKY WAY TIDAL STREAM REACHING BEYOND 100 kpc". United States. https://doi.org/10.1088/0004-637X/765/2/154.
@article{osti_22126967,
title = {EVIDENCE FOR A MILKY WAY TIDAL STREAM REACHING BEYOND 100 kpc},
author = {Drake, A. J. and Djorgovski, S. G. and Graham, M. J. and Mahabal, A. and Donalek, C. and Williams, R. and Catelan, M. and Torrealba, G. and Prieto, J. L. and Larson, S. and Christensen, E. and Beshore, E.},
abstractNote = {We present the analysis of 1207 RR Lyrae found in photometry taken by the Catalina Survey's Mount Lemmon telescope. By combining accurate distances for these stars with measurements for {approx}14,000 type-ab RR Lyrae from the Catalina Schmidt telescope, we reveal an extended association that reaches Galactocentric distances beyond 100 kpc and overlaps the Sagittarius stream system. This result confirms earlier evidence for the existence of an outer halo tidal stream resulting from a disrupted stellar system. By comparing the RR Lyrae source density with that expected based on halo models, we find the detection has {approx}8{sigma} significance. We investigate the distances, radial velocities, metallicities, and period-amplitude distribution of the RR Lyrae. We find that both radial velocities and distances are inconsistent with current models of the Sagittarius stream. We also find tentative evidence for a division in source metallicities for the most distant sources. Following prior analyses, we compare the locations and distances of the RR Lyrae with photometrically selected candidate horizontal branch stars and find supporting evidence that this structure spans at least 60 Degree-Sign of the sky. We investigate the prospects of an association between the stream and the unusual globular cluster NGC 2419.},
doi = {10.1088/0004-637X/765/2/154},
url = {https://www.osti.gov/biblio/22126967}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 765,
place = {United States},
year = {Sun Mar 10 00:00:00 EST 2013},
month = {Sun Mar 10 00:00:00 EST 2013}
}