J/ApJ/926/141 3-D kinematics of Orion Nebula Cluster (Theissen+, 2022)
The 3-D kinematics of the Orion Nebula Cluster:
NIRSPEC-AO radial velocities of the core population.
Theissen C.A, Konopacky Q.M., Lu J.R., Kim D., Zhang S.Y., Hsu C.H.,
Chu L., Wei L.
<Astrophys. J. 926, 141 (2022)>
=2022ApJ...926..141T 2022ApJ...926..141T (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Radial velocities ; Proper motions ;
Rotational velocities ; Effective temperatures ;
Spectra, infrared ; Spectra, optical
Keywords: stellar kinematics - radial velocity - star formation -
star forming regions - open star clusters - stellar associations
Abstract:
The kinematics and dynamics of stellar and substellar populations
within young, still-forming clusters provide valuable information for
constraining theories of formation mechanisms. Using Keck II
NIRSPEC+AO data, we have measured radial velocities for 56 low-mass
sources within 4' of the core of the Orion Nebula Cluster (ONC). We
also remeasure radial velocities for 172 sources observed with
SDSS/APOGEE. These data are combined with proper motions measured
using HST ACS/WFPC2/WFC3IR and Keck II NIRC2, creating a sample of 135
sources with all three velocity components. The velocities measured
are consistent with a normal distribution in all three components. We
measure intrinsic velocity dispersions of
(σνα, σνβ, σνδ ) =
(1.64±0.12, 2.03±0.13, 2.560.170.16) km/s. Our computed
intrinsic velocity dispersion profiles are consistent with the
dynamical equilibrium models from Da Rio et al. (2017ApJ...845..105D 2017ApJ...845..105D)
in the tangential direction but not in the line-of-sight direction,
possibly indicating that the core of the ONC is not yet virialized,
and may require a nonspherical potential to explain the observed
velocity dispersion profiles. We also observe a slight elongation
along the north-south direction following the filament, which has
been well studied in previous literature, and an elongation in the
line-of-sight to tangential velocity direction. These 3D kinematics
will help in the development of realistic models of the formation and
early evolution of massive clusters.
Description:
We obtained high-resolution near-IR (NIR) spectra of the sources
closest to the core of the ONC-surrounding the Trapezium-using
Keck/NIRSPAO between 2015 and 2020.
Using Keck/NIRSPAO, we have obtained high-precision RV measurements
(σ≤0.5km/s) for a large number of sources within the core
region of the ONC (41 sources within 1'). Additionally, we included a
reanalysis of 172 ONC sources observed with SDSS/APOGEE. Using a
combined sample of Keck/NIRSPAO, SDSS/APOGEE, and PM measurements from
Kim et al. (2019AJ....157..109K 2019AJ....157..109K, Cat. J/AJ/157/109), for a total
sample of 135 sources, we presented a 3D study of the kinematics of
the core population of the ONC.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 93 56 NIRSPEC forward-modeling results
table5.dat 117 172 APOGEE forward-modeling results
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See also:
J/ApJ/540/236 : KH photometry of Orion Nebula Cluster (Hillenbrand+, 2000)
J/AJ/157/109 : Stellar proper motions in the Orion Nebula Cluster (Kim+, 2019)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- [HC2000] Identifier Hillenbrand & Carpenter,
2000ApJ...540..236H 2000ApJ...540..236H, Cat. J/ApJ/540/236
4 A1 --- m_[HC2000] [AB] Multiplicty index on [HC2000]
6- 8 I3 --- ID ? Kim et al. (2019AJ....157..109K 2019AJ....157..109K,
Cat. J/AJ/157/109) identifier
10- 20 F11.8 deg RAdeg Right Ascension (J2000)
22- 32 F11.8 deg DEdeg Declination (J2000)
34- 38 F5.2 km/s RV Radial velocity
40- 43 F4.2 km/s e_RV Radial velocity uncertainty (1)
45- 49 F5.2 mas/yr pmRA ? Proper motion in Right Ascension,
pmRA*cosDE
51- 54 F4.2 mas/yr e_pmRA ? Proper motion in Right Ascension uncertainty
56- 60 F5.2 mas/yr pmDE ? Proper motion in Declination
62- 65 F4.2 mas/yr e_pmDE ? Proper motion in Declination uncertainty
67- 70 I4 K Teff Model effective temperature (2)
72- 74 I3 K e_Teff Model effective temperature uncertainty
76- 80 F5.2 km/s vsini Rotational velocity
82- 85 F4.2 km/s e_vsini Rotational velocity uncertainty
87- 90 F4.2 --- Veiling Order 33 veiling parameter
92- 93 A2 --- Note Note (3)
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Note (1): Reported uncertainties also include the 0.058km/s systematic
uncertainty between calibration frames, and the 0.5% variation found
from differing logg and Teff.
Note (2): Continuum veiling causes extreme degeneracies with Teff. Caution
should be taken when using derived temperatures with high veiling.
Note (3): Note as follows:
B = double star, previously known in the literature
BC = new binary candidates, previously reported as single in the literature
E1 = escape group 1
E2 = escape group 2
V = RV variable source
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- APOGEE APOGEE 2MASS Identifier
20- 22 I3 --- ID ? Kim et al. (2019AJ....157..109K 2019AJ....157..109K,
Cat. J/AJ/157/109) Identifier
24- 34 F11.8 deg RAdeg Right Ascension (J2000)
36- 46 F11.8 deg DEdeg Declination (J2000)
48- 52 F5.2 km/s RV Radial velocity
54- 58 F5.2 km/s e_RV Radial velocity uncertainty
60- 64 F5.2 mas/yr pmRA ? Proper motion in Right Ascension,
pmRA*cosDE
66- 69 F4.2 mas/yr e_pmRA ? Proper motion in Right Ascension uncertainty
71- 75 F5.2 mas/yr pmDE ? Proper motion in Declination
77- 80 F4.2 mas/yr e_pmDE ? Proper motion in Declination uncertainty
82- 88 F7.2 K Teff Model effective temperature (1)
90- 95 F6.2 K e_Teff Model effective temperature uncertainty
97-102 F6.2 km/s vsini Rotational velocity
104-109 F6.2 km/s e_vsini Rotational velocity uncertainty
111-114 F4.2 --- Veiling H-band veiling parameter
116-117 A2 --- Note Note (2)
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Note (1): Continuum veiling causes extreme degeneracies with Teff. Caution
should be taken when using derived temperatures with high veiling.
Note (2): Note as follows:
C = close companion to source (≲1-arcsec)
E3 = escape group 3
V = RV variable source
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Acknowledgements:
Christopher Theissen, ctheissen(at)ucsd.edu
(End) Patricia Vannier [CDS] 15-Mar-2022