Signatures of a Tidally Induced Spiral Arm at the Anticenter of the Milky Way and a Kinematically Extended Anticenter Stream Using DESI Data Release 2

Abstract Using the Dark Energy Spectroscopic Instrument (DESI) Milky Way Survey, we examine the six-dimensional space of the anticenter region of the Milky Way stellar disk (150° < Galactic longitude < 220°) using 61,883 main-sequence turnoff stars. We focus on two well-known stellar overdensities in the anticenter: the Monoceros Ring (MRi) and Anticenter Stream (ACS). We find that the MRi overdensity has kinematic signatures consistent with a tidally induced spiral arm, a type of dynamic spiral arm created by an interaction with a satellite galaxy, most likely the Sagittarius dwarf spheroidal galaxy (Sgr). We use the kinematics of the MRi to calculate the two most recent passage times of Sgr, finding 0.25 ± 0.09 Gyr and 1.10 ± 0.23 Gyr from the present day. We validate that the ACS is kinematically decoupled from the MRi because they are moving in opposite radial and vertical directions. We find that the kinematics associated with the ACS extends beyond our defined overdensity. The features we see in the ACS region are likely part of a broader distribution of stars with the same kinematic signature as detected in other places, like the vertical wave in the outer disk and phase spiral.

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Publication Details

Journal
The Astronomical Journal
Published
2026-04-15
DOI
https://doi.org/10.3847/1538-3881/ae5100
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
0.00

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article

Signatures of a Tidally Induced Spiral Arm at the Anticenter of the Milky Way and a Kinematically Extended Anticenter Stream Using DESI Data Release 2

Will J. Percival, Mika Lambert, S X Li, Rongpu Zhou et al.
The Astronomical Journal
Stellar, planetary, and galactic studies
article

Signatures of a Tidally Induced Spiral Arm at the Anticenter of the Milky Way and a Kinematically Extended Anticenter Stream Using DESI Data Release 2

Will J. Percival, Mika Lambert, S X Li, Rongpu Zhou, T J Li, João A. S. Amarante, S. Nadathur, David Sprayberry, David J. Schlegel, Ignasi Pérez-Ràfols, Axel de la Macorra, B. A. Weaver, Martin Landriau, Marc Manera, Gaston Gutierrez, J. Aguilar, Anthony Kremin, Adam Myers, Namitha Kizhuprakkat, Nathan R. Sandford, Joan Najita, J. E. Forero-Romero, Steven P. Ahlen, Aaron Meisner, R. Miquel, John Moustakas, Leandro José Beraldo e Silva, Amanda Byström, Monica Valluri, C. Lamman, Laurent Le Guillou, P. Doel, G Tarle, Francisco Prada, Kyle Dawson, Joseph H. Silber, Gustavo E. Medina, Sergey E. Koposov, Eusebio Sanchez, Hu Zou, Graziano Rossi, Todd Claybaugh, Michael Schubnell, Davide Bianchi, Richard Joyce, David Brooks, Enrique Gaztañaga, Satya Gontcho A Gontcho
article en

Abstract

Abstract Using the Dark Energy Spectroscopic Instrument (DESI) Milky Way Survey, we examine the six-dimensional space of the anticenter region of the Milky Way stellar disk (150° < Galactic longitude < 220°) using 61,883 main-sequence turnoff stars. We focus on two well-known stellar overdensities in the anticenter: the Monoceros Ring (MRi) and Anticenter Stream (ACS). We find that the MRi overdensity has kinematic signatures consistent with a tidally induced spiral arm, a type of dynamic spiral arm created by an interaction with a satellite galaxy, most likely the Sagittarius dwarf spheroidal galaxy (Sgr). We use the kinematics of the MRi to calculate the two most recent passage times of Sgr, finding 0.25 ± 0.09 Gyr and 1.10 ± 0.23 Gyr from the present day. We validate that the ACS is kinematically decoupled from the MRi because they are moving in opposite radial and vertical directions. We find that the kinematics associated with the ACS extends beyond our defined overdensity. The features we see in the ACS region are likely part of a broader distribution of stars with the same kinematic signature as detected in other places, like the vertical wave in the outer disk and phase spiral.

The Astronomical JournalVol. 171(5)
Boston University (US), Institució Catalana de Recerca i Estudis Avançats (ES), Universidad Complutense de Madrid (ES), Universitat Autònoma de Barcelona (ES), University of Wyoming (US), Centre National de la Recherche Scientifique (FR), Fermi National Accelerator Laboratory (US), Lawrence Berkeley National Laboratory (US), University of Waterloo (CA), Universidad de Los Andes (CO), Universidad Autónoma de la Ciudad de México (MX), Shanghai Jiao Tong University (CN), Perimeter Institute (CA), University of California, Santa Cruz (US), University of Toronto (CA), Institute for High Energy Physics (ES), University of Milan (IT), Chinese Academy of Sciences (CN), University of Utah (US), National Tsing Hua University (TW), University of Michigan (US), Brera Astronomical Observatory (IT), Sejong University (KR), Sorbonne Université (FR), Valongo Observatory (BR), Institut d'Estudis Espacials de Catalunya (ES), Laboratoire de Physique Nucléaire et de Hautes Énergies (FR), Royal Observatory (GB), Institute of Space Sciences (ES), Michigan Medicine (US), Institut National de Physique Nucléaire et de Physique des Particules (FR), Community Science and Data Center (US), NSF NOIRLab (US), Instituto de Astrofísica de Andalucía (ES), National Astronomical Observatories (CN), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (ES), University College London (GB), University of Virginia (US), The Ohio State University (US), University of Portsmouth (GB), Michigan State University (US), Universidad Nacional Autónoma de México (MX), Siena College (US), Universitat Politècnica de Catalunya (ES), University of Edinburgh (GB)
National Science Foundation, U.S. Department of Energy, Gordon and Betty Moore Foundation, Ministerio de Ciencia, Innovación y Universidades, National Energy Research Scientific Computing Center, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Office of Science, Science and Technology Facilities Council, Agencia Estatal de Investigación, Division of Astronomical Sciences, High Energy Physics
Openalex Percentile: Top 23%
Stellar, planetary, and galactic studies
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