Abstract
We present a newly found wave-like pattern in mean Galactocentric radial velocity (U) over bar (g) versus guiding centre radius R-g or angular momentum L-z of stars in the RV subsample of Gaia DR2. The short-wave pattern has a wavelength of order 1.2 kpc in R-g or 285 kpc km s(-1) in L-z. The pattern shows only weak changes with Galactocentric radius R and little change in strength in particular with the vertical energy E-z of the stars or the distance to the Galactic plane vertical bar z vertical bar. The pattern is to first order symmetric around the plane, i.e. has no significant odd terms in z. There is a weak phase shift with the pattern moving towards slightly lower L-z (i.e. trailing) with vertical bar z vertical bar and E-z. However, we observe a highly significant phase shift in Galactic azimuth phi, which is different for different peaks. The peak around L-z similar to 2100 kpc km s(-1) only shows a weak change with phi, while the rest of the pattern shows a clearly detectable shift of dL(z)/d phi = (200 +/- 22) kpc km s(-1) rad(-1). If we consider all peaks to belong to the same pattern, this would suggest a wavenumber m = 4. We further find that the wave-like pattern in U-g appears to be related to the (W) over bar versus L-z pattern detected in Gaia DR1. A comparison of the (U) over bar (g)-L-z wave pattern with changes of (U) over bar (g) versus R, which have been previously discussed, suggests that the latter can be understood as just the (U) over bar (g)- L-z pattern washed out by blurring (i.e. orbital excursions around their guiding centre) of disc stars.
| Dokumententyp: | Zeitschriftenartikel |
|---|---|
| Fakultät: | Physik |
| Themengebiete: | 500 Naturwissenschaften und Mathematik > 530 Physik |
| ISSN: | 0035-8711 |
| Sprache: | Englisch |
| Dokumenten ID: | 82541 |
| Datum der Veröffentlichung auf Open Access LMU: | 15. Dez. 2021, 15:01 |
| Letzte Änderungen: | 15. Dez. 2021, 15:01 |
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