A Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius Stream
We present a chemical and dynamical analysis of the leading arm (LA) and trailing arm (TA) of the Sagittarius (Sgr) stream, as well as for the Sgr dwarf galaxy core (SC), using red giant branch, main-sequence, and RR Lyrae stars from large spectroscopic survey data. The different chemical properties...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/ace32b |
| _version_ | 1827820920866078720 |
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| author | Gwibong Kang Young Sun Lee Young Kwang Kim Timothy C. Beers |
| author_facet | Gwibong Kang Young Sun Lee Young Kwang Kim Timothy C. Beers |
| author_sort | Gwibong Kang |
| collection | DOAJ |
| description | We present a chemical and dynamical analysis of the leading arm (LA) and trailing arm (TA) of the Sagittarius (Sgr) stream, as well as for the Sgr dwarf galaxy core (SC), using red giant branch, main-sequence, and RR Lyrae stars from large spectroscopic survey data. The different chemical properties among the LA, TA, and SC generally agree with recent studies and can be understood by a radial metallicity gradient established in the progenitor of the Sgr dwarf, followed by preferential stellar stripping from the outer part of the Sgr progenitor. One striking finding is a relatively larger fraction of low-eccentricity stars ( e < 0.4) in the LA than in the TA and SC. The TA and SC exhibit very similar distributions. Considering that a tidal tail stripped off from a dwarf galaxy maintains the orbital properties of its progenitor, we expect that the e -distribution of the LA should be similar to that of the TA and SC. Thus, the disparate behavior of the e -distribution of the LA is of particular interest. Following the analysis of Vasiliev et al., we attempt to explain the different e -distribution by introducing a time-dependent perturbation of the Milky Way by the Large Magellanic Cloud's (LMC) gravitational pull, resulting in substantial evolution of the angular momentum of the LA stars to produce the low- e stars. In addition, we confirm from RR Lyrae stars with high eccentricity ( e > 0.6) that the TA stars farther away from the SC are also affected by disturbances from the LMC. |
| first_indexed | 2024-03-12T01:35:16Z |
| format | Article |
| id | doaj.art-8fbe9e20d87f4a228e8558d263292681 |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T01:35:16Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-8fbe9e20d87f4a228e8558d2632926812023-09-11T08:52:37ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019542L4310.3847/2041-8213/ace32bA Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius StreamGwibong Kang0https://orcid.org/0009-0004-2765-1986Young Sun Lee1https://orcid.org/0000-0001-5297-4518Young Kwang Kim2https://orcid.org/0000-0002-6411-5857Timothy C. Beers3https://orcid.org/0000-0003-4573-6233Department of Astronomy, Space Science, and Geology, Chungnam National University , Daejeon 34134, Republic of KoreaDepartment of Astronomy and Space Science, Chungnam National University , Daejeon 34134, Republic of Korea ; youngsun@cnu.ac.kr; Department of Physics and Astronomy and JINA Center for the Evolution of the Elements, University of Notre Dame , IN 46556, USADepartment of Astronomy and Space Science, Chungnam National University , Daejeon 34134, Republic of Korea ; youngsun@cnu.ac.krDepartment of Physics and Astronomy and JINA Center for the Evolution of the Elements, University of Notre Dame , IN 46556, USAWe present a chemical and dynamical analysis of the leading arm (LA) and trailing arm (TA) of the Sagittarius (Sgr) stream, as well as for the Sgr dwarf galaxy core (SC), using red giant branch, main-sequence, and RR Lyrae stars from large spectroscopic survey data. The different chemical properties among the LA, TA, and SC generally agree with recent studies and can be understood by a radial metallicity gradient established in the progenitor of the Sgr dwarf, followed by preferential stellar stripping from the outer part of the Sgr progenitor. One striking finding is a relatively larger fraction of low-eccentricity stars ( e < 0.4) in the LA than in the TA and SC. The TA and SC exhibit very similar distributions. Considering that a tidal tail stripped off from a dwarf galaxy maintains the orbital properties of its progenitor, we expect that the e -distribution of the LA should be similar to that of the TA and SC. Thus, the disparate behavior of the e -distribution of the LA is of particular interest. Following the analysis of Vasiliev et al., we attempt to explain the different e -distribution by introducing a time-dependent perturbation of the Milky Way by the Large Magellanic Cloud's (LMC) gravitational pull, resulting in substantial evolution of the angular momentum of the LA stars to produce the low- e stars. In addition, we confirm from RR Lyrae stars with high eccentricity ( e > 0.6) that the TA stars farther away from the SC are also affected by disturbances from the LMC.https://doi.org/10.3847/2041-8213/ace32bMilky Way dynamicsSagittarius dwarf spheroidal galaxyStellar streamsDwarf galaxiesStellar dynamicsStellar abundances |
| spellingShingle | Gwibong Kang Young Sun Lee Young Kwang Kim Timothy C. Beers A Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius Stream The Astrophysical Journal Letters Milky Way dynamics Sagittarius dwarf spheroidal galaxy Stellar streams Dwarf galaxies Stellar dynamics Stellar abundances |
| title | A Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius Stream |
| title_full | A Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius Stream |
| title_fullStr | A Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius Stream |
| title_full_unstemmed | A Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius Stream |
| title_short | A Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius Stream |
| title_sort | dynamically distinct stellar population in the leading arm of the sagittarius stream |
| topic | Milky Way dynamics Sagittarius dwarf spheroidal galaxy Stellar streams Dwarf galaxies Stellar dynamics Stellar abundances |
| url | https://doi.org/10.3847/2041-8213/ace32b |
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