A study of full space motions of outer Galactic disc A and F stars in two deep pencil beams

Harris, A.; Drew, J. E.; Monguió, M.

doi:10.1093/mnras/stz442

Cited by 5 publications

(1 citation statement)

References 47 publications

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“…With the astrometry in hand along with the RV measurements, the components of motion in the Galactic frame have been determined using the relations laid out by Harris et al (2019) as their equations 1 and 2 (for u, v, w, where it should be understood u = −vR, v = v φ and w = v φ ). A step in this process involves the calculation of the Galactocentric radii of the stars in the sample.…”

Section: Space Velocitiesmentioning

confidence: 99%

Radial velocities from far red spectra of Carina Arm O and early B stars

Drew¹,

Parsons²,

Mohr-Smith³

2022

Preprint

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Massive O and early B stars are important markers of recent star formation and exert a significant influence on their environments during their short lives via photoionization and winds and when they explode as supernovae. In the Milky Way they can be detected at great distances but often lie behind large dust columns, making detection at short wavelengths difficult. In this study the use of the less extinguished far-red spectrum (8400 -8800 Å) for radial velocity measurement is examined. Results are reported for a sample of 164 confirmed OB stars within a 2-degree field positioned on the Carina Arm. Most stars are at distances between 3 and 6 kpc, and Westerlund 2 is at the field edge. The measured radial velocities have errors concentrated in the 3-10 km s −1 range, with a systematic uncertainty of 2-3 km s −1 . These are combined with Gaia-mission astrometry to allow full space motions to be constructed. Up to 22 stars are likely to be runaways although 8 of them are as likely to be interloping (so far undetected) binaries. The mean azimuthal motion of the sample fits in with recent measurements of Galactic disk rotation. In the Galactocentric radial direction the mean motion indicates modest infall at a speed of ∼ 10 km s −1 . This experiment shows that weak Paschen lines in the far-red can yield credible radial velocity determination, offering the prospect of exploring OB-star kinematics over much more of the Galactic disk than has hitherto been possible.

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Section: Space Velocitiesmentioning

confidence: 99%

Radial velocities from far red spectra of Carina Arm O and early B stars

Drew¹,

Parsons²,

Mohr-Smith³

2022

Preprint

View full text Add to dashboard Cite

show abstract

Exploring the structure and kinematics of the Milky Way through A stars

Ardèvol¹,

Monguió²,

Figueras³

et al. 2023

A&A

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Context. Despite their relatively high intrinsic brightness and the fact that they are more numerous than younger OB stars and kinematically colder than older red giants, A-type stars have rarely been used as Galactic tracers. They may, in fact, be used to fill the age gap between these two tracers, thereby allowing us to evaluate the evolutionary and dynamic processes underlying the transition between them. Aims. We analyse Galactic disc structure and kinematic perturbations up to 6 kpc from the Sun based on observations of A-type stars. Methods. This work presents a catalogue of A-type stars selected using the IGAPS photometric survey. It covers the Galactic disc within 30° ≤l ≤ 215° and |b|≤5° up to a magnitude of r ≤ 19 mag with about 3.5 million sources. We used Gaia Data Release 3 parallaxes and proper motions, as well as the line-of-sight velocities, to analyse the large-scale features of the Galactic disc. We carried out a study of the completeness of the detected density distributions, along with a comparison between the b < 0° and b > 0° regions. Possible biases caused by interstellar extinction or by the usage of some kinematic approximations were examined as well. Results. We find stellar overdensities associated with the Local and the Perseus spiral arms, as well as with the Cygnus region. We find that A-type stars also provide kinematic indications of the Galactic warp towards the anticentre, which displays a median vertical motion of ∼6 − 7 km s−1 at a Galactocentric radius of R = 14 kpc. It starts at R ≈ 12 kpc, which supports the scenario where the warp begins at larger radii for younger tracers when compared with other samples in the literature. We also detect a region with downward mean motion extending beyond 2 kpc from the Sun towards 60° ≲l ≲ 75° that may be associated with a compression breathing mode. Furthermore, A-type stars reveal very clumpy inhomogeneities and asymmetries in the VZ − Vϕ velocity space plane.

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Radial velocities from far-red spectra of Carina Arm O and early B stars

Drew

Blake-Parsons

Mohr-Smith

2022

Monthly Notices of the Royal Astronomical Society

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Massive O and early B stars are important markers of recent star formation and exert a significant influence on their environments during their short lives via photoionization and winds and when they explode as supernovae. In the Milky Way they can be detected at great distances but often lie behind large dust columns, making detection at short wavelengths difficult. In this study the use of the less extinguished far-red spectrum (8400 – 8800 Å) for radial velocity measurement is examined. Results are reported for a sample of 164 confirmed OB stars within a 2-degree field positioned on the Carina Arm. Most stars are at distances between 3 and 6 kpc, and Westerlund 2 is at the field edge. The measured radial velocities have errors concentrated in the 3–10 km s−1 range, with a systematic uncertainty of 2–3 km s−1. These are combined with Gaia-mission astrometry to allow full space motions to be constructed. Up to 22 stars are likely to be runaways although 8 of them are as likely to be interloping (so far undetected) binaries. The mean azimuthal motion of the sample fits in with recent measurements of Galactic disk rotation. In the Galactocentric radial direction the mean motion indicates modest infall at a speed of ∼ 10 km s−1. This experiment shows that weak Paschen lines in the far-red can yield credible radial velocity determination, offering the prospect of exploring OB-star kinematics over much more of the Galactic disk than has hitherto been possible.

show abstract

A study of full space motions of outer Galactic disc A and F stars in two deep pencil beams

Cited by 5 publications

References 47 publications

Radial velocities from far red spectra of Carina Arm O and early B stars

Radial velocities from far red spectra of Carina Arm O and early B stars

Exploring the structure and kinematics of the Milky Way through A stars

Radial velocities from far-red spectra of Carina Arm O and early B stars

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