The GALAH survey and Gaia DR2: Dissecting the stellar disc's phase space by age, action, chemistry, and location

the GALAH team

Research output: Contribution to journalReview article

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Abstract

We use the second data releases of the European Space AgencyGaia astrometric survey and the high-resolution Galactic Archaeology with HERMES (GALAH) spectroscopic survey to analyse the structure of our Galaxy's disc components. With GALAH, we separate the α-rich and α-poor discs (with respect to Fe), which are superposed in both position and velocity space, and examine their distributions in action space. We study the distribution of stars in the zVz phase plane, for both Vφ and VR, and recover the remarkable 'phase spiral' discovered by Gaia. We identify the anticipated quadrupole signature in zVz of a tilted velocity ellipsoid for stars above and below the Galactic plane. By connecting our work with earlier studies, we show that the phase spiral is likely to extend well beyond the narrow solar neighbourhood cylinder in which it was found. The phase spiral is a signature of corrugated waves that propagate through the disc, and the associated non-equilibrium phase mixing. The radially asymmetric distribution of stars involved in the phase spiral reveals that the corrugation, which is mostly confined to the α-poor disc, grows in z-amplitude with increasing radius. We present new simulations of tidal disturbance of the Galactic disc by the Sagittarius (Sgr) dwarf. The effect on the zVz phase plane lasts ≥2Gyr, but a subsequent disc crossing wipes out the coherent structure. We find that the phase spiral was excited ≤0.5 Gyr ago by an object like Sgr with total mass ∼3 × 1010 M (stripped down from ∼5 × 1010 M when it first entered the halo) passing through the plane.

Original languageEnglish
Pages (from-to)1167-1191
Number of pages25
JournalMonthly Notices of the Royal Astronomical Society
Volume486
Issue number1
DOIs
Publication statusPublished - 1 Jan 2019

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archaeology
chemistry
stars
signatures
virtual reality
solar neighborhood
disk galaxies
ellipsoids
halos
disturbance
disturbances
quadrupoles
radii
high resolution
simulation
distribution

Cite this

@article{7e2df7a7b74e4106864668acfb566dd3,
title = "The GALAH survey and Gaia DR2: Dissecting the stellar disc's phase space by age, action, chemistry, and location",
abstract = "We use the second data releases of the European Space AgencyGaia astrometric survey and the high-resolution Galactic Archaeology with HERMES (GALAH) spectroscopic survey to analyse the structure of our Galaxy's disc components. With GALAH, we separate the α-rich and α-poor discs (with respect to Fe), which are superposed in both position and velocity space, and examine their distributions in action space. We study the distribution of stars in the zVz phase plane, for both Vφ and VR, and recover the remarkable 'phase spiral' discovered by Gaia. We identify the anticipated quadrupole signature in zVz of a tilted velocity ellipsoid for stars above and below the Galactic plane. By connecting our work with earlier studies, we show that the phase spiral is likely to extend well beyond the narrow solar neighbourhood cylinder in which it was found. The phase spiral is a signature of corrugated waves that propagate through the disc, and the associated non-equilibrium phase mixing. The radially asymmetric distribution of stars involved in the phase spiral reveals that the corrugation, which is mostly confined to the α-poor disc, grows in z-amplitude with increasing radius. We present new simulations of tidal disturbance of the Galactic disc by the Sagittarius (Sgr) dwarf. The effect on the zVz phase plane lasts ≥2Gyr, but a subsequent disc crossing wipes out the coherent structure. We find that the phase spiral was excited ≤0.5 Gyr ago by an object like Sgr with total mass ∼3 × 1010 M⊙ (stripped down from ∼5 × 1010 M⊙ when it first entered the halo) passing through the plane.",
keywords = "astrometry, Galaxy: disc, evolution, structure, proper motions, stars: kinematics and dynamics",
author = "{the GALAH team} and Joss Bland-Hawthorn and Sanjib Sharma and Thor Tepper-Garcia and James Binney and Freeman, {Ken C.} and Hayden, {Michael R.} and Janez Kos and {De Silva}, {Gayandhi M.} and Simon Ellis and Lewis, {Geraint F.} and Martin Asplund and Sven Buder and Casey, {Andrew R.} and Valentina D'Orazi and Ly Duong and Shourya Khanna and Jane Lin and Karin Lind and Martell, {Sarah L.} and Ness, {Melissa K.} and Simpson, {Jeffrey D.} and Zucker, {Daniel B.} and Tomaž Zwitter and Kafle, {Prajwal R.} and Quillen, {Alice C.} and Ting, {Yuan Sen} and Wyse, {Rosemary F.G.}",
year = "2019",
month = "1",
day = "1",
doi = "10.1093/mnras/stz217",
language = "English",
volume = "486",
pages = "1167--1191",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "OXFORD UNIV PRESS UNITED KINGDOM",
number = "1",

}

The GALAH survey and Gaia DR2 : Dissecting the stellar disc's phase space by age, action, chemistry, and location. / the GALAH team.

In: Monthly Notices of the Royal Astronomical Society, Vol. 486, No. 1, 01.01.2019, p. 1167-1191.

Research output: Contribution to journalReview article

TY - JOUR

T1 - The GALAH survey and Gaia DR2

T2 - Dissecting the stellar disc's phase space by age, action, chemistry, and location

AU - the GALAH team

AU - Bland-Hawthorn, Joss

AU - Sharma, Sanjib

AU - Tepper-Garcia, Thor

AU - Binney, James

AU - Freeman, Ken C.

AU - Hayden, Michael R.

AU - Kos, Janez

AU - De Silva, Gayandhi M.

AU - Ellis, Simon

AU - Lewis, Geraint F.

AU - Asplund, Martin

AU - Buder, Sven

AU - Casey, Andrew R.

AU - D'Orazi, Valentina

AU - Duong, Ly

AU - Khanna, Shourya

AU - Lin, Jane

AU - Lind, Karin

AU - Martell, Sarah L.

AU - Ness, Melissa K.

AU - Simpson, Jeffrey D.

AU - Zucker, Daniel B.

AU - Zwitter, Tomaž

AU - Kafle, Prajwal R.

AU - Quillen, Alice C.

AU - Ting, Yuan Sen

AU - Wyse, Rosemary F.G.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - We use the second data releases of the European Space AgencyGaia astrometric survey and the high-resolution Galactic Archaeology with HERMES (GALAH) spectroscopic survey to analyse the structure of our Galaxy's disc components. With GALAH, we separate the α-rich and α-poor discs (with respect to Fe), which are superposed in both position and velocity space, and examine their distributions in action space. We study the distribution of stars in the zVz phase plane, for both Vφ and VR, and recover the remarkable 'phase spiral' discovered by Gaia. We identify the anticipated quadrupole signature in zVz of a tilted velocity ellipsoid for stars above and below the Galactic plane. By connecting our work with earlier studies, we show that the phase spiral is likely to extend well beyond the narrow solar neighbourhood cylinder in which it was found. The phase spiral is a signature of corrugated waves that propagate through the disc, and the associated non-equilibrium phase mixing. The radially asymmetric distribution of stars involved in the phase spiral reveals that the corrugation, which is mostly confined to the α-poor disc, grows in z-amplitude with increasing radius. We present new simulations of tidal disturbance of the Galactic disc by the Sagittarius (Sgr) dwarf. The effect on the zVz phase plane lasts ≥2Gyr, but a subsequent disc crossing wipes out the coherent structure. We find that the phase spiral was excited ≤0.5 Gyr ago by an object like Sgr with total mass ∼3 × 1010 M⊙ (stripped down from ∼5 × 1010 M⊙ when it first entered the halo) passing through the plane.

AB - We use the second data releases of the European Space AgencyGaia astrometric survey and the high-resolution Galactic Archaeology with HERMES (GALAH) spectroscopic survey to analyse the structure of our Galaxy's disc components. With GALAH, we separate the α-rich and α-poor discs (with respect to Fe), which are superposed in both position and velocity space, and examine their distributions in action space. We study the distribution of stars in the zVz phase plane, for both Vφ and VR, and recover the remarkable 'phase spiral' discovered by Gaia. We identify the anticipated quadrupole signature in zVz of a tilted velocity ellipsoid for stars above and below the Galactic plane. By connecting our work with earlier studies, we show that the phase spiral is likely to extend well beyond the narrow solar neighbourhood cylinder in which it was found. The phase spiral is a signature of corrugated waves that propagate through the disc, and the associated non-equilibrium phase mixing. The radially asymmetric distribution of stars involved in the phase spiral reveals that the corrugation, which is mostly confined to the α-poor disc, grows in z-amplitude with increasing radius. We present new simulations of tidal disturbance of the Galactic disc by the Sagittarius (Sgr) dwarf. The effect on the zVz phase plane lasts ≥2Gyr, but a subsequent disc crossing wipes out the coherent structure. We find that the phase spiral was excited ≤0.5 Gyr ago by an object like Sgr with total mass ∼3 × 1010 M⊙ (stripped down from ∼5 × 1010 M⊙ when it first entered the halo) passing through the plane.

KW - astrometry

KW - Galaxy: disc, evolution, structure

KW - proper motions

KW - stars: kinematics and dynamics

UR - http://www.scopus.com/inward/record.url?scp=85067176006&partnerID=8YFLogxK

U2 - 10.1093/mnras/stz217

DO - 10.1093/mnras/stz217

M3 - Review article

VL - 486

SP - 1167

EP - 1191

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 1

ER -