Galactic spiral structure revealed byGaiaEDR3

Abstract

Using the astrometry and integrated photometry from the Gaia Early Data Release 3, we map the density variations in the distribution of young upper main sequence (UMS) stars, open clusters, and classical Cepheids in the Galactic disc within several kiloparsecs of the Sun. We derive maps of relative over- and under-dense regions for UMS stars in the Galactic disc using both bivariate kernel density estimators and wavelet transformations. The resulting overdensity maps exhibit large-scale arches that extend in a clumpy but coherent way over the entire sampled volume, indicating the location of the spiral arm segments in the vicinity of the Sun. Peaks in the UMS overdensity are well matched by the distribution of young and intrinsically bright open clusters. By applying a wavelet transformation to a sample of classical Cepheids, we find that their overdensities possibly extend the spiral arm segments on a larger scale (≃10 kpc from the Sun). While the resulting map based on the UMS sample is generally consistent with previous models of the Sagittarius-Carina spiral arm, the geometry of the arms in the III quadrant (galactic longitudes 180° < l < 270°) differs significantly from that suggested by many previous models. In particular, we find that our maps favour a larger pitch angle for the Perseus arm, and that the Local Arm extends into the III quadrant at least 4 kpc past the position of the Sun, giving it a total length of at least 8 kpc.

Zeta-Payne: A Fully Automated Spectrum Analysis Algorithm for the Milky Way Mapper Program of the SDSS-V Survey

“…The structure of the galaxy as revealed by its young stellar components, in particular the kinematics, dynamics, and nature of the Galactic spiral arms. Zari et al (2021) demonstrated that the structure of the Milky Way as traced with young OB-type stars is not necessarily the same as deduced from observations of red giants, from analysis of the distribution of dust in the galaxy, or from the distributions of Cepheids and/or masers (see also Poggio et al 2021). The authors found that the distribution of OBA-type stars in the plane is highly structured, with pronounced over-and underdensities, and conclude that young stars in the galaxy are not neatly organized into distinct spiral arms.…”

The PLATO field selection process I. Identification and content of the long-pointing fields

“…8, lower panels). On top of this, the faint tail of the P1 and most of P5 sample probe even larger distances (up to d 1000 pc), where the spiral structure of the Milky Way starts to be discernible (Miyachi et al 2019;Poggio et al 2021) and the basic assumption of spatial homogeneity breaks.…”

Signatures of anisotropic diffusion around PeVatrons in 100 TeV gamma-ray data

“…To determine the most likely locations for individual PeVatrons in the outer Galaxy, we briefly review in this section the structure of the Milky Way disk and outline the model we use in the calculations of the subsequent sections. The Milky Way is a four-armed barred spiral galaxy [7,8]. The Sun is located at the distance D = 8.15±0.15 kpc [9] from the Galactic Center, in the immediate vicinity of the Orion -or "Local"-arm, which lies between the Sun and the Perseus arm, see Fig.…”