Stellar Stream Candidates in the Solar Neighborhood Found in the LAMOST DR3 and TGAS

Liang, Xian-Ting; Zhao, Jingkun; Oswalt, Terry D.; Chen, Yuqin; Zhang, Lan; Zhao, Gang

doi:10.3847/1538-4357/aa7cf7

Cited by 28 publications

(32 citation statements)

References 36 publications

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“…Spatial region of this selected sample is similar to region 3 in Liang et al (2017) and it contains the spatial region of V6 from Ramos, Antoja & Figueras (2018). Therefore our contours look very similar to subplot (b) of figure 5 of Liang et al (2017) and subplot (f) of figure 5 of Ramos, Antoja & Figueras (2018). However, the peak around (0, 7) km/s in our figure is much more significant than in theirs which are only in dense regions but not density peaks.…”

Section: Methodssupporting

confidence: 68%

“…We call it a new moving group candidate since it is so obvious for the first time. The difference between our data and Liang et al (2017) lies in that this sample is selected from LAMOST DR5 cross-matched with Gaia DR2 rather than Gaia DR1 TGAS. The difference between our data and Ramos, Antoja & Figueras (2018) mainly lies in that Ramos, Antoja & Figueras (2018) used the Gaia DR2 sample and we used only G,K giants with radial velocity from LAMOST.…”

Section: Methodsmentioning

confidence: 72%

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A New Moving Group in the Local Arm

Liang

Zhao

Chen

et al. 2020

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We present a new moving group clustered in kinematics, spatial position and elemental abundances. Its spatial position is around the center of the Local Arm of the Milky Way. A convergent point method was taken to select candidate member stars. Among 206 candidate member stars, 74 are pre-main-sequence stars and some of them have stellar disks. We presume those pre-main sequence stars belong to Orion nebula. We suggest this moving group is caused by density wave of the Local Arm passing by.

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Section: Methodssupporting

confidence: 68%

Section: Methodsmentioning

confidence: 72%

A New Moving Group in the Local Arm

Liang

Zhao

Chen

et al. 2020

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“…The Hercules stream, first seen in Eggen (1958) and later detected in multiple surveys such as Hipparcos, RAVE, LAMOST and Gaia (e.g. Dehnen 1998;Antoja et al 2012;Liang et al 2017;Gaia Collaboration et al 2018a), is revealed as an elongated region in the UV-plane with a characteristic velocity moving away from the Galactic center, U ≈ −30 − 50 km s −1 and lagging behind the local standard of rest (LSR), V ≈ −60 km s −1 . Discarded the hypothesis of the disruption of a cluster as its origin, given Send offprint requests to: S. Torres ⋆ Email; santiago.torres@upc.edu their spread in ages and metallicities (e.g.…”

Section: Introductionmentioning

confidence: 99%

Gaia DR2 white dwarfs in the Hercules stream

Torres

Cantero

Camisassa

et al. 2019

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Aims. We analyzed the velocity space of the thin and thick-disk Gaia white dwarf population within 100 pc looking for signatures of the Hercules stellar stream. We aimed to identify those objects belonging to the Hercules stream and, by taking advantage of white dwarf stars as reliable cosmochronometers, to derive a first age distribution. Methods. We applied a kernel density estimation to the UV velocity space of white dwarfs. For the region where a clear overdensity of stars was found, we created a 5-D space of dynamic variables. We applied a hierarchichal clustering method, HDBSCAN, to this 5-D space, identifying those white dwarfs that share similar kinematic characteristics. Finally, under general assumptions and from their photometric properties, we derived an age estimate for each object. Results. The Hercules stream was firstly revealed as an overdensity in the UV velocity space of the thick-disk white dwarf population. Three substreams were then found: Hercules a and Hercules b, formed by thick-disk stars with an age distribution peaked 4 Gyr in the past and extended to very old ages; and Hercules c, with a ratio of 65:35 thin:thick stars and a more uniform age distribution younger than 10 Gyr

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“…Based on small spreads of the metallicity within the group, authors explain its origin as being a dissolving remnant of a globular cluster. Liang et al (2017) applied a wavelet analysis technique to a sample that is a combination of the LAMOST DR3 (Zhao et al 2012) and the Gaia TGAS (Michalik et al 2015) catalogues. They detected 16 kinematic structures were found and four of them are potential new stream candidates.…”

Section: Introductionmentioning

confidence: 99%

Kinematic structures of the solar neighbourhood revealed byGaiaDR1/TGAS and RAVE

Kushniruk

Schirmer

Bensby

2017

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Context. The velocity distribution of stars in the Solar neighbourhood is inhomogeneous and rich with stellar streams and kinematic structures. These may retain important clues of the formation and dynamical history of the Milky Way. However, the nature and origin of many of the streams and structures is unclear, hindering our understanding of how the Milky Way formed and evolved. Aims. We aim to study the velocity distribution of stars of the Solar neighbourhood and investigate the properties of individual kinematic structures in order to improve our understanding of their origins. Methods. Using the astrometric data provided by Gaia DR1/TGAS and radial velocities from RAVE DR5 we perform a wavelet analysis with the à trous algorithm to 55 831 stars that have U and V velocity uncertainties less than 4 km s −1 . An auto-convolution histogram method is used to filter the output data, and we then run Monte Carlo simulations to verify that the detected structures are real due to velocity uncertainties. Additionally we analysed our stellar sample by splitting all stars into a nearby sample (< 300 pc) and a distant sample (> 300 pc), and two chemically defined samples that to a first degree represent the thin and the thick disks. Results. We detect 19 kinematic structures in the Solar neighbourhood between scales 3 − 16 km s −1 at the 3σ confidence level. Among them we identified well-known groups (such as Hercules, Sirius, Coma Berenices, Pleiades, and Wolf 630), confirmed recently detected groups (such as Antoja12 and Bobylev16), and detected a new structure at (U, V) ≈ (37, 8) km s −1 . Another three new groups are tentatively detected, but require further confirmation. Some of the detected groups show clear dependence on distance in the sense that they are only present in the nearby sample (< 300 pc), and others appear to be correlated with chemistry as they are only present in either of the chemically defined thin and thick disk samples. Conclusions. With the much enlarged stellar sample and much increased precision in distances, proper motions, provided by Gaia DR1 TGAS we have shown that the velocity distribution of stars in the Solar neighbourhood contains more structures than previously known. A new feature is discovered and three recently detected groups are confirmed at high confidence level. Dividing the sample based on distance and/or metallicity shows that there are variety of structures which are as large-scale and small-scale groups, some of them have clear trends on metallicities, others are a mixture of both disk stars and based on that we discuss possible origin of each group.

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Stellar Stream Candidates in the Solar Neighborhood Found in the LAMOST DR3 and TGAS

Cited by 28 publications

References 36 publications

A New Moving Group in the Local Arm

A New Moving Group in the Local Arm

Gaia DR2 white dwarfs in the Hercules stream

Kinematic structures of the solar neighbourhood revealed byGaiaDR1/TGAS and RAVE

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