J/AJ/159/287 Stellar parameters in Ophiuchus Stream with MMT (Caldwell+, 2020)
A larger extent for the Ophiuchus Stream.
Caldwell N., Bonaca A., Price-Whelan A.M., Sesar B., Walker M.G.
<Astron. J., 159, 287 (2020)>
=2020AJ....159..287C 2020AJ....159..287C
ADC_Keywords: Clusters, globular; Milky Way; Spectra, optical;
Radial velocities; Proper motions; Parallaxes, trigonometric
Keywords: Galaxy structure ; Galaxy stellar halos ; Milky Way stellar halo ;
Globular star clusters
Abstract:
We present new kinematic data for the Ophiuchus stellar stream.
Spectra have been taken of member candidates at the Multiple Mirror
Telescope (MMT) using Hectospec, Hectochelle, and Binospec, which
provide more than 1800 new velocities. Combined with proper-motion
measurements of stars in the field by the Gaia-DR2 catalog, we have
derived stream membership probabilities, resulting in the detection of
more than 200 likely members. These data show the stream extends to
more than three times the length shown in the discovery data. A spur
to the main stream is also detected. The high-resolution spectra allow
us to resolve the stellar velocity dispersion, found to be
1.6±0.3km/s.
Description:
This paper uses three different spectrographs on the Multiple Mirror
Telescope (MMT), and is complemented with the Gaia DR2 data.
A total of nine separate Hectospec fields were observed in 2016 using
the Multiple Mirror Telescope and Hectospec instrument with the 600gpm
grating, which gave spectra in the range of 4030-6500Å, with a
resolution of 2.3Å. More than 1700 stars were observed with
Hectospec.
This instrument is a new low-resolution, multi-slit spectrograph on
the MMT. We employed the 1000gpm grating that gives spectral
resolution of 1.5Å over a range of 1500Å. We centered the
spectra at 5200Å, which allowed the inclusion of the Hβ line
as well as the Mgb lines.
In the latter stages of composing this paper, some additional MMT
telescope time became available that was used again with the
Hectochelle instrument. The observing setup was similar to that for
the Sesar+, 2015, J/ApJ/809/59 data, except that a different
wavelength region was used: 6135-6320Å. The total exposure time on
the single 1deg field was 15700 s. 80 stars were targeted.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 140 2645 Spectroscopic observations
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See also:
II/249 : WHAM Northern Sky Survey, V-1.1 (Haffner+, 2003)
II/349 : The Pan-STARRS release 1 (PS1) Survey-DR1 (Chambers+, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/AJ/137/94 : Star clusters in M31 (Caldwell+, 2009)
J/A+A/530/A31 : Stellar parameters in 10 globular cluster (Lane+, 2011)
J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011)
J/AcA/62/357 : Proper motions in 6 globular clusters (Zloczewski+, 2012)
J/ApJ/809/59 : Ophiuchus stellar stream with PS1 data (Sesar+, 2015)
J/ApJ/816/L4 : Candidate BHB stars in Ophiuchus stream (Sesar+, 2016)
J/MNRAS/482/5138 : Galactic GC mean PMs & velocities (Baumgardt+, 2019)
J/AJ/158/14 : Stellar pop. globular clusters using APOGEE (Nataf+, 2019)
J/AJ/158/223 : RR Lyrae memb. of Pal 5 stellar stream (Price-Whelan+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ref Reference code (1)
7- 15 F9.5 deg RAdeg [239/248] Right Ascension (J2000)
17- 24 F8.5 deg DEdeg [-8.97/-5.61] Declination (J2000)
26- 31 F6.3 mag gmag [15.2/22.3] PS1 g band magnitude
33- 37 F5.3 mag e_gmag [0/1.04] Uncertainty in gmag
39- 44 F6.3 mag imag [14.7/21.7] PS1 i band magnitude
46- 50 F5.3 mag e_imag [0/0.76] Uncertainty in imag
52- 57 F6.3 mag (g-i)0 [-0.92/100] Dereddened (g-i) color (2)
59- 63 F5.3 mag e_(g-i)0 [0/1.04] Uncertainty in (g-i)0
65- 70 F6.3 mag i0mag [14.3/100] Dereddened PS1 i band magnitude
72- 77 F6.1 km/s RVel [-916/767]? Radial velocity
79- 82 F4.1 km/s e_RVel [0.2/81]? Uncertainty in RVel
84- 87 F4.1 --- R [2/70.6] Correlation coefficient (3)
89- 95 F7.3 mas/yr pmRA* [-36/21]? Proper motion along RA times cos(DE)
97-101 F5.3 mas/yr e_pmRA* [0.07/5.3]? Uncertainty in pmRA*
103-110 F8.3 mas/yr pmDE [-125/11]? Proper motion along DE
112-116 F5.3 mas/yr e_pmDE [0.04/3.2]? Uncertainty in pmDE
118-123 F6.3 mas plx [-4.68/8.19]? Gaia DR2 parallax (4)
125-129 F5.3 mas e_plx [0.03/2.14]? Uncertainty in plx
131-135 F5.1 --- D [0/127] Angular distance to stream fiducial
137-140 F4.2 --- Pmem [0/1]? Membership probability
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Note (1): References as follows:
A = Sesar+, 2016, J/ApJ/816/L4
E = Sesar+, 2015, J/ApJ/809/59 (Hectospec)
D = Sesar+, 2015, J/ApJ/809/59 (Deimos)
H = This work (Hectospec)
B = This work (Binospec)
F = This work (Hectochelle)
Note (2): Dereddened using the maps of Schlafly+, 2014ApJ...789...15S 2014ApJ...789...15S
Note (3): In broad terms, R values greater than 4 means that the derived
radial velocity can be trusted.
Note (4): We do not add in the +0.05mas correction as discussed in the text.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 14-Sep-2020