J/ApJ/939/68 Absolute motions of the Arches and Quintuplet (Hosek+, 2022)
Measuring the Orbits of the Arches and Quintuplet Clusters Using HST and Gaia:
Exploring Scenarios for Star Formation near the Galactic Center.
Hosek M.W.Jr, Do T., Lu J.R., Morris M.R., Ghez A.M., Martinez G.D.,
Anderson J.
<Astrophys. J., 939, 68 (2022)>
=2022ApJ...939...68H 2022ApJ...939...68H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Proper motions ; Photometry, infrared
Keywords: Galactic center - young star clusters - Star formation - Astrometry
Abstract:
We present new absolute proper-motion measurements for the Arches and
Quintuplet clusters, two young massive star clusters near the Galactic
center. Using multiepoch HST observations, we construct proper-motion
catalogs for the Arches (∼35000 stars) and Quintuplet (∼40000 stars)
fields in ICRF coordinates established using stars in common with the
Gaia EDR3 catalog. The bulk proper motions of the clusters are
measured to be (µRA*cosDE, µDE)=(-0.80±0.032,
-1.89±0.021) mas yr-1 for the Arches and (µα*,
µδ) = (-0.96±0.032, -2.29±0.023) mas yr-1 for the
Quintuplet, achieving ≥5x higher precision than past measurements.
We place the first constraints on the properties of the cluster orbits
that incorporate the uncertainty in their current line-of-sight
distances. The clusters will not approach closer than ∼25pc to Sgr A*,
making it unlikely that they will inspiral into the nuclear star
cluster within their lifetime. Further, the cluster orbits are not
consistent with being circular; the average value of rapo/rperi is
∼1.9 (equivalent to an eccentricity of ∼0.31) for both clusters.
Lastly, we find that the clusters do not share a common orbit,
challenging one proposed formation scenario in which the clusters
formed from molecular clouds on the open stream orbit derived by
Kruijssen et al. (2015MNRAS.447.1059K 2015MNRAS.447.1059K). Meanwhile, our constraints on
the birth location and velocity of the clusters offer mild support for
a scenario in which the clusters formed via collisions between gas
clouds on the x1 and x2 bar orbit families.
Description:
Stellar proper motions are measured using four epochs of HST/WFC3-IR
observations of both clusters taken between 2010 - 2016 (GO-11671, PI
Ghez; GO-12318, PI Ghez; GO-12667, PI Ghez; GO-14613, PI Lu).
Astrometry is extracted in the F153M filter and is transformed into
the Gaia DR3 reference frame using stars in common with the Gaia EDR3
catalog. F127M and F139M observations were obtained in 2010 provide
additional stellar photometry. All photometric measurements are
reported in Vega magnitudes.
A cluster membership probability is calculated for each star based on
the Gaussian Mixture Model derived to describe the proper motion
distributions of the cluster and field star populations. Details can
be found in Appendix B of the paper.
Objects:
------------------------------------------------------------------------
RA (2000) DE Designation(s)
------------------------------------------------------------------------
17 45 50.650 -28 49 19.51 Arches cluster = NAME Arches Cluster
17 46 14.686 -28 49 38.99 Quintuplet cluster = NAME Quintuplet Cluster
------------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 131 34600 Absolute proper motion catalog of the
Arches Cluster
table4.dat 131 40499 Absolute proper motion catalog of the
Quintuplet Cluster
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See also:
J/ApJ/581/258 : Infrared photometry in the Arches Cluster (Figer+, 2002)
J/A+A/501/563 : HKs photometry in the Arches cluster (Espinoza+, 2009)
J/A+A/494/1137 : Quintuplet cluster K-band spectral catalog (Liermann+, 2009)
J/ApJ/718/810 : Arches cluster astrometry and photometry (Stolte+, 2010)
J/ApJ/751/132 : Keck observations of the Arches cluster (Clarkson+, 2012)
J/A+A/556/A26 : Arches cluster: IR phot., extinction & masses (Habibi+, 2013)
J/A+A/578/A4 : Photometry and motions in Arches & Quintuplet (Stolte+, 2015)
J/A+A/617/A65 : Stellar population of the Arches cluster (Clark+, 2018)
J/A+A/618/A2 : Quintuplet cluster updated stellar census (Clark+, 2018)
J/ApJ/789/115 : Quintuplet cluster astrometry and photometry (Stolte+, 2019)
J/ApJ/789/115 : Quintuplet cluster astrometry and photometry (Stolte+, 2019)
J/A+A/647/A110 : Arches cluster JVLA 6 & 10GHz images (Gallego-Calvente+, 2021)
Byte-by-byte Description of file: table3.dat table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Star Name
10- 14 F5.2 mag F127M ? F127M magnitude
16- 19 F4.2 mag e_F127M ? Error on F127M magnitude
21- 25 F5.2 mag F139M ? F139M magnitude
27- 30 F4.2 mag e_F139M ? Error on F139M magnitude
32- 36 F5.2 mag F153M ? F153M magnitude
38- 41 F4.2 mag e_F153M ? Error on F153M magnitude
43- 52 F10.5 arcsec dRA RA*cosDE position offset (1)
54- 60 F7.5 arcsec e_dRA Error in RA*cosDE position offset
62- 70 F9.5 arcsec dDE DE position offset (1)
72- 78 F7.5 arcsec e_dDE Error in DE position offset
80- 85 F6.2 mas/yr pmRA Proper motion in RA*cosDE
87- 90 F4.2 mas/yr e_pmRA Error in Proper motion in RA*cosDE
92- 97 F6.2 mas/yr pmDE Proper motion in DE
99-102 F4.2 mas/yr e_pmDE Error in proper motion in DE
104-112 F9.4 yr t0 Time
114 I1 --- Nobs Number of Epochs Observed
116-120 F5.2 --- chi2RA Chi2 of proper motion fit in RA*cosDE
122-126 F5.2 --- chi2DE Chi2 of proper motion fit in DE
128-131 F4.2 --- Pclust Cluster membership probability
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Note (1): for table3.dat (Arches Cluster), positions are relative to
(RA0, DE0) = (17:45:50.65020, -28:49:19.51468) (J2000)
for table4.dat (Quintuplet Cluster), positions are relative to
(RA0, DE0) = (17:46:14.68579, -28:49:38.99169) (J2000)
--------------------------------------------------------------------------------
Acknowledgements:
Matthew Hosek Jr, mwhosek(at)astro.ucla.edu
(End) Prepared by [AAS], Patricia Vannier [CDS] 15-May-2023