Title: GD-1: The Relic of an Old Metal-poor Globular Cluster

Abstract

Combining data from Gaia DR2, SDSS DR14 and LAMOST DR6, we update the fit tomodel of the properties of the stellar stream GD-1 and find that it has an ageof $$\sim 13$$ Gyr, [Fe/H] of $$-2.2\pm 0.12$$, and a distance from the sun of $$\sim 8$$ kpc. We tabulate 6D phase-space fiducial points along the GD-1 streamorbit over a 90$$^\circ$$ arc. The fitted orbit shows that the stream has aneccentricity $$e \sim 0.3$$, perigalacticon of 14.2 kpc, apogalacticon of 27.0 kpc and inclination $$i \sim 40^{\circ}$$. There is evidence along the arc for 4candidate stellar overdensities, one candidate gap, two candidate stellarunderdensities and is cut off at $$\phi_1 \sim 2^{\circ}$$ (in the stream-aligned$$(\phi_1,\phi_2)$$ coordinate system. The spur originating at $$\phi_1 \sim -40^{\circ}$$ implies stars were pulled away from the stream traceby an encounter (potentially a dark matter subhalo). The narrowest place ( FWHM$$\sim 44.6$$ pc) of the GD-1 trace is at $$(\phi_1, \phi_2^c) \sim (-14^{\circ},0.15^{\circ})$$, which is $$\sim (178.18^{\circ}, 52.19^{\circ})$$ in (R. A.,Decl.), where the progenitor is possibly located. In conclusion, we also find six BHB and 10BS spectroscopic stars in the GD-1 stream.

Authors:

Li, Guang -Wei  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-7515-6307"

Yanny, Brian  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-9541-2678"

Wu, Yue ^[1]

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+ Show Author Affiliations

1. Chinese Academy of Sciences (CAS), Beijing (China)
2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

Publication Date:

Tue Dec 18 00:00:00 EST 2018

Research Org.:

Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP)

OSTI Identifier:

1498554

Report Number(s):

arXiv:1811.06427; FERMILAB-PUB-18-746-CD
Journal ID: ISSN 1538-4357; 1722223

Grant/Contract Number:  

AC02-07CH11359

Resource Type:

Accepted Manuscript

Journal Name:

The Astrophysical Journal (Online)

Additional Journal Information:

Journal Name: The Astrophysical Journal (Online); Journal Volume: 869; Journal Issue: 2; Journal ID: ISSN 1538-4357

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; Galaxy: abundances; Galaxy: kinematics and dynamics; Galaxy: structure; globular clusters: general