Detecting the Sagittarius stream with LAMOST DR4 M giants \& Gaia DR2

Abstract

We use LAMOST DR4 M giants combined with Gaia DR2 proper motions and ALLWISE photometry to obtain an extremely pure sample of Sagittarius (Sgr) stream stars. Using TiO5 and CaH spectral indices as an indicator, we selected out a large sample of M giant stars from M dwarf stars in LAMOST DR4 spectra. Considering the position, distance, proper motion and the angular momentum distribution, we obtained 164 pure Sgr stream stars. We find that the trailing arm has higher energy than the leading arm in same angular momentum. The trailing arm we detected extends to a heliocentric distance of $\sim 130$ kpc at ${\tilde{\Lambda }}_{\odot }\sim 170^{\circ }$, which is consistent with the feature found in RR Lyrae in \citet{sgr2017}. Both of these detections of Sgr, in M giants and in RR Lyrae, imply that the Sgr stream may contain multiple stellar populations with a broad metallicity range.

19 pages, 7 figures, 1 table, submitted to ApJ

References in corpus (10)

• The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy
• Revised metallicity classes for low-mass stars: dwarfs (dM), subdwarfs (sdM), extreme subdwarfs (esdM), and ultra subdwarfs (usdM)
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: Variation of the Metallicity Distribution Function Along the Sagittarius Stream
• A Tail of Two Populations: Chemo-dynamics of the Sagittarius Stream and Implications for its Original Mass
• APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy
• The SDSS-2MASS-WISE Ten Dimensional Stellar Color Locus
• The $>100$ kpc Distant Spur of the Sagittarius Stream and the Outer Virgo Overdensity, as Seen in PS1 RR Lyrae Stars
• Predicted Extension of the Sagittarius Stream to the Milky Way Virial Radius
• Carbon stars from LAMOST DR2 data
• Exposing Sgr tidal debris behind the Galactic disk with M giants selected in WISE$\cap$2MASS

Cited by in corpus (4)

• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• An all-sky proper motion map of the Sagittarius stream using Gaia DR2
• Tracing Kinematic and Chemical Properties of Sagittarius Stream by K-Giants, M-Giants, and BHB stars
• The Pristine survey -- VII. A cleaner view of the Galactic outer halo using blue horizontal branch stars