Benjamin, R.A.

Castro Ginard, A.

De Souza, R.S.

Hillenbrand, L.

Ishida, E.E.O.

Krone-Martins, A.

Kuhn, M.A.

Povich, M.

Zucker, C.

Leiden University Scholary Publications

Identification of a spur-like structure in the Milky Way's Sagittarius armKuhn, M.A.; Benjamin, R.A.; Zucker, C.; Krone-Martins, A.; De Souza, R.S.; Castro Ginard, A.;... ; Hillenbrand, L.CitationKuhn, M. A., Benjamin, R. A., Zucker, C., Krone-Martins, A., De Souza, R. S., Castro Ginard,A., … Hillenbrand, L. (2022). Identification of a spur-like structure in the Milky Way'sSagittarius arm. Bulletin Of The American Astronomical Society, (6). Retrieved fromhttps://hdl.handle.net/1887/3562728 Version: Publisher's VersionLicense: Creative Commons CC BY 4.0 licenseDownloaded from: https://hdl.handle.net/1887/3562728 Note: To cite this publication please use the final published version (if applicable).Bulletin of the AAS • Vol. 54, Issue 6Identi cation of a Spur-like Structure in the MilkyWay’s Sagittarius ArmMichael A. Kuhn1 Robert A. Benjamin2 Catherine Zucker3Alberto Krone-Martins4 Rafael S. de Souza5 Alfred Castro-Ginard6Emille E. O. Ishida7 Matthew Povich8 Lynne Hillenbrand11California Institute of Technology, 2University of Wisconsin, Whitewater,3Space Telescope Science Institute, 4UC Irvine, 5Shanghai Astronomical Observatory,6Universiteit Leiden, 7Université Clermont Auvergne,8California State Polytechnic University, PomonaPublished on: Jun 29, 2022URL: https://baas.aas.org/pub/2022n6i216p01License: Creative Commons Attribution 4.0 International License (CC-BY 4.0)Bulletin of the AAS • Vol. 54, Issue 6 Identi cation of a Spur-like Structure in the Milky Way’s Sagittarius Arm2ESA’s Gaia mission has provided an unprecedented 3D view of our Solar neighborhood out to several kpc, allowing us to better understand how local star-forming regions fit into our galaxy’s spiral structure. We report the identification of a kpc-long spatially and kinematically coherent structure in the Galactic plane between Galactic longitudes 4 deg and 19 deg at a distance of ~1-2 kpc. This filament-like structure is comprised of groups of young stellar objects (YSOs) identified in the Spitzer/IRAC Candidate YSO (SPICY) catalog and molecular clouds observed by multiple submillimeter surveys. The structure’s 3D configuration and motions were derived from Gaia EDR3 astrometry combined with molecular cloud radial velocities. The structure includes several prominent star-forming regions, notably Messier 8, 16, 17, and 20, along with multiple newly identified young stellar groups. These regions have historically formed part of the Sagittarius spiral arm, but the new 3D view shows that this structure is discrete and has a pitch angle (psi = 56 deg) significantly greater than expected for an arm segment. The structure experiences shear of 4.6 km/s/kpc due to Galactic rotation, suggesting a timescale of ~90 Myr for the structure to change pitch angle by a factor of 2. The high pitch angle is reminiscent of “spurs” detected in other spiral galaxies, and we discuss alternative interpretations of this structure as a spur or a mass concentration within the Sagittarius Arm.

Identification of a spur-like structure in the Milky Way's Sagittarius arm

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Identification of a spur-like structure in the Milky Way's Sagittarius arm

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