J/ApJ/911/149 Spectroscopic obs. in ATLAS and Aliqa Uma streams (Li+, 2021)
Broken into pieces: ATLAS and Aliqa Uma as one single stream.
Li T.S., Koposov S.E., Erkal D., Ji A.P., Shipp N., Pace A.B., Hilmi T.,
Kuehn K., Lewis G.F., Mackey D., Simpson J.D., Wan Z., Zucker D.B.,
Bland-Hawthorn J., Cullinane L.R., Da Costa G.S., Drlica-Wagner A.,
Hattori K., Martell S.L., Sharma S., The S5 Collaboration
<Astrophys. J., 911, 149 (2021)>
=2021ApJ...911..149L 2021ApJ...911..149L
ADC_Keywords: Associations, stellar; Abundances, [Fe/H]; Radial velocities;
Stars, horizontal branch; Stars, variable; Spectra, optical;
Photometry
Keywords: Tidal disruption ; Stellar kinematics ; Stellar motion ;
Stellar associations ; Metallicity ; Stellar abundances ;
Dark matter ; Milky Way dark matter halo ; Stellar streams ;
Milky Way dynamics
Abstract:
We present the first spectroscopic measurements of the ATLAS and Aliqa
Uma streams from the Southern Stellar Stream Spectroscopic Survey
(S5), in combination with the photometric data from the Dark Energy
Survey and astrometric data from Gaia. From the coherence of
spectroscopic members in radial velocity and proper motion, we find
that these two systems are extremely likely to be one stream with
discontinuity in morphology and density on the sky (the "kink"
feature). We refer to this entire stream as the ATLAS-Aliqa Uma
stream, or the AAU stream. We perform a comprehensive exploration of
the effect of baryonic substructures and find that only an encounter
with the Sagittarius dwarf ∼0.5Gyr ago can create a feature similar to
the observed "kink." In addition, we also identify two gaps in the
ATLAS component associated with the broadening in the stream width
(the "broadening" feature). These gaps have likely been created by
small mass perturbers, such as dark matter halos, as the AAU stream is
the most distant cold stream known with severe variations in both the
stream surface density and the stream track on the sky. With the
stream track, stream distance, and kinematic information, we determine
the orbit of the AAU stream and find that it has been affected by the
Large Magellanic Cloud, resulting in a misalignment between the proper
motion and stream track. Together with the Orphan-Chenab Stream, AAU
is the second stream pair that has been found to be a single stream
separated into two segments by external perturbation.
Description:
The ATLAS and Aliqa Uma streams were observed in 2018 as part of the
Southern Stellar Stream Spectroscopic Survey (S5 program), which
uses the AAOmega spectrograph on the 3.9m Anglo-Australian Telescope
(AAT), fed by the Two Degree Field ("2dF") fiber positioner facility,
allowing the acquisition of up to 392 simultaneous spectra of objects
within a 2° field in diameter on the sky. We refer readers to
Paper I (Li+ 2019, J/MNRAS/490/3508) for details on the survey
strategy, target selection, observation, and reduction of S5.
A total of five AAT fields were observed in Aliqa Uma and 12 fields in
ATLAS, with a total covered length of the stream of about 34° on
the sky.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 96 A total of 96 spectroscopic members in ATLAS stream
and Aliqa Uma stream
table2.dat 50 18 Blue horizontal branch (BHB) and RR Lyrae (RRL)
members in ATLAS stream and Aliqa Uma stream
table3.dat 75 25 A total of 25 spectroscopic members in Palca stream,
found in the ATLAS-Aliqa Uma (AAU) stream fields
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See also:
II/350 : VLT Survey Telescope ATLAS (Shanks+, 2015)
II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)
J/A+A/466/181 : BVI photometry of Whiting 1 (Carraro+, 2007)
J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJ/757/83 : The Blanco Cosmology Survey (BCS) (Desai+, 2012)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/MNRAS/434/1681 : Extremely metal-poor stars CaII triplet (Carrera+, 2013)
J/A+A/561/A87 : FLAMES observations of Terzan 8 (Carretta+, 2014)
J/ApJ/834/57 : MW molecular clouds from 12CO (Miville-Deschenes+, 2017)
J/A+A/616/A10 : Open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)
J/ApJ/866/22 : Spectroscopic analysis of Tuc III stream (Li+, 2018)
J/MNRAS/481/1195 : Gaia DR2 RRL stars as standard candles (Muraveva+, 2018)
J/MNRAS/482/5138 : Galactic GC mean PMs & velocities (Baumgardt+, 2019)
J/AJ/158/223 : RRL members of Pal 5 stellar stream (Price-Whelan+, 2019)
J/ApJ/885/3 : Membership in 12 stellar streams from DES (Shipp+, 2019)
J/MNRAS/484/2832 : Proper motions of MW globular clusters (Vasiliev, 2019)
J/MNRAS/490/3508 : The Southern Stellar Stream Sp. Survey (S5) (Li+, 2019)
J/AJ/159/287 : Stellar parameters in Oph Stream with MMT (Caldwell+, 2020)
J/AJ/160/181 : Chemical abundances in red giants with Magellan (Ji+, 2020)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Gaia Gaia DR2 source identifier
21- 29 F9.6 deg RAdeg [9.1/40.4] Gaia DR2 Right Ascension in decimal
degrees (ICRS) at Ep=2015.5
31- 40 F10.6 deg DEdeg [-37.6/-20.4] Gaia DR2 Declination in decimal
degrees (ICRS) at Ep=2015.5
42- 45 F4.1 --- SNR [2.6/77.5] Signal-to-Noise
47- 51 F5.2 mag Gmag [14.96/19.58] Gaia DR2 G band magnitude
53- 59 F7.2 km/s RVel [-157/-5] Heliocentric radial velocity
61- 65 F5.2 km/s e_RVel [0.6/21] Uncertainty in RVel
67- 71 F5.2 [Sun] [Fe/H] [-2.71/-1.93]? Metallicity
73- 76 F4.2 [Sun] e_[Fe/H] [0.1/0.53]? Uncertainty in [Fe/H]
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Gaia Gaia DR2 source identifier
21- 29 F9.6 deg RAdeg [9.97/38.25] Gaia DR2 Right Ascension in decimal
degrees (ICRS) at Ep=2015.5
31- 40 F10.6 deg DEdeg [-35.82/-20.8] Gaia DR2 Declination in decimal
degrees (ICRS) at Ep=2015.5
42- 46 F5.2 mag m-M [16.21/17.29] Distance modulus
48- 50 A3 --- Cl Tracer identifier (1)
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Note (1): Tracer identifier as follows:
bhb = blue horizontal branch star (13 occurrences)
rrl = RR Lyrae star (5 occurrences)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Gaia Gaia DR2 source identifier
21- 29 F9.6 deg RAdeg [29.75/39.6] Gaia DR2 Right Ascension in decimal
degrees (ICRS) at Ep=2015.5
31- 40 F10.6 deg DEdeg [-37.86/-31.5] Gaia DR2 Declination in decimal
degrees (ICRS) at Ep=2015.5
42- 45 F4.1 --- SNR [2.9/75.3] Signal-to-Noise
47- 51 F5.2 mag Gmag [15.44/19.5] Gaia DR2 G band magnitude
53- 58 F6.2 km/s RVel [81/118] Heliocentric radial velocity
60- 64 F5.2 km/s e_RVel [0.6/34] Uncertainty in RVel
66- 70 F5.2 [Sun] [Fe/H] [-2.21/-1.57]? Metallicity
72- 75 F4.2 [Sun] e_[Fe/H] [0.1/0.34]? Uncertainty in [Fe/H]
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History:
From electronic version of the journal
References:
Li et al. Paper I. 2019MNRAS.490.3508L 2019MNRAS.490.3508L Cat. J/MNRAS/490/3508
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Oct-2022