J/ApJ/961/113 Isochrone ages of action-angle groups in Gaia (Furnkranz+, 2024)
The age distribution of stellar orbit space clumps.
Furnkranz V., Rix H.-W., Coronado J., Seeburger R.
<Astrophys. J., 961, 113 (2024)>
=2024ApJ...961..113F 2024ApJ...961..113F
ADC_Keywords: Milky Way; Associations, stellar; Stars, ages; Clusters, open
Keywords: Milky Way dynamics ; Milky Way disk ; Solar neighborhood ;
Stellar kinematics ; Star clusters ; Stellar associations ;
Galactic archaeology
Abstract:
The orbit distribution of young stars in the Galactic disk is highly
structured, from well-defined clusters to streams of stars that may be
widely dispersed across the sky, but are compact in orbital
action-angle space. The age distribution of such groups can constrain
the timescales over which conatal groups of stars disperse into the
"field." Gaia data have proven powerful in identifying such groups in
action-angle space, but the resulting member samples are often too
small and have too narrow a color-magnitude diagram (CMD) coverage to
allow robust age determinations. Here, we develop and illustrate a new
approach that can estimate robust stellar population ages for such
groups of stars. This first entails projecting the predetermined
action-angle distribution into the 5D space of positions, parallaxes,
and proper motions, where much larger samples of likely members can be
identified over a much wider range of the CMD. It then entails
isochrone fitting that accounts for: (a) widely varying distances and
reddenings; (b) outliers and binaries; (c) sparsely populated
main-sequence turnoffs, by incorporating the age information of the
low-mass main sequence; and (d) the possible presence of an intrinsic
age spread in the stellar population. When we apply this approach to
92 nearby stellar groups identified in 6D orbit space, we find that
they are predominantly young (≲1Gyr), mono-age populations. Many
groups are established (known) localized clusters with possible tidal
tails, while others tend to be widely dispersed and manifestly
unbound. This new age-dating tool offers a stringent approach to
understanding on which orbits stars form in the solar neighborhood and
how quickly they disperse into the field.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 69 49265 Group membership selection
table2.dat 157 92 Main parameters of the 92 action-angle groups
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
J/A+A/624/L11 : Coma Berenices neighbor moving group (Fuernkranz+, 2019)
J/AJ/158/122 : Local structure & SFH of the MW (Kounkel+, 2019)
J/A+A/624/L11 : Coma Berenices neighbor moving group (Fuernkranz+, 2019)
J/A+A/622/L13 : Stellar stream in Gaia DR2 discovery (Meingast+, 2019)
J/A+A/627/A4 : Praesepe (NGC 2632) and its tidal tails (Roeser+, 2019)
J/A+A/621/L2 : Hyades tidal tails revealed by Gaia DR2 (Roeser+, 2019)
J/ApJ/877/12 : Coma Ber & a Neighbor Stellar Group tidal tails (Tang+, 2019)
J/A+A/640/A1 : Portrait Galactic disc (Cantat-Gaudin+, 2020)
J/A+A/645/A84 : Coronae of nearby star clusters (Meingast+, 2021)
J/ApJ/928/70 : Gaia EDR3 members stars of 55 FoF groups (Coronado+, 2022)
J/ApJ/936/160 : Properties of 328 stellar strings (Zucker+, 2022)
J/A+A/673/A114 : Improving the open cluster census. II. (Hunt+, 2023)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Gaia Gaia DR3 source identifier
21- 42 F22.18 deg RAdeg Gaia DR3 Right Ascension (ICRS) at Epoch=2016.0
44- 66 F23.19 deg DEdeg [-89/90] Gaia DR3 Declination
(ICRS) at Epoch=2016.0)
68- 69 I2 --- Group [1/92] Group number
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Group [1/92] Group number
4- 7 I4 --- Nstar [107/5236] Number of member stars
9- 28 F20.17 kpc.km.s-1 Jr [0.098/41.22] Action in the radial
direction
30- 47 F18.13 kpc.km.s-1 Jp [1561.3/1976.3] Action in the angular
direction
49- 68 F20.18 kpc.km.s-1 Jz [0.018/2.11] Action in the z direction
70- 88 F19.17 rad Theta-r [0.06/6.26] Angle in the radial direction
90- 109 F20.18 rad Theta-p [0.0079/6.28] Angle in the angular
direction
111- 129 F19.17 rad Theta-z [0.11/6.25] Angle in the z direction
131- 134 F4.2 [yr] logAge [7.3/9.3] Log Age
136- 139 F4.2 [yr] sigmaAge [0.05/0.45] Intrinsic age spread
141- 143 F3.1 [-] FeH [0/0.1] Metallicity
145- 157 A13 --- Cluster Literature Name (1)
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Note (1): For the subset of 62 groups which we identified in the
cluster catalog by Cantat-Gaudin+ (2020, J/A+A/640/A1), we list the
literature name in the last column, as well as for the Meingast 1
(Pisces-Eridanus) stellar stream that we identified from
Meingast+ (2019, J/A+A/622/L13).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Apr-2026