Metallicity Distribution in M31 and M33 Based on the Tip of the Red Giant Branch Near-infrared Color
This study investigates the metallicity distribution in M31 and M33 by using the near-infrared color index J − K of the tip of the red giant branch (TRGB) of the member stars from Y. Ren et al. after removing foreground dwarf stars by a near-infrared J − H versus H − K diagram as well as Gaia astrom...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
|
| Series: | The Astronomical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-3881/add14e |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850219480566726656 |
|---|---|
| author | Ying Li Biwei Jiang Yi Ren |
| author_facet | Ying Li Biwei Jiang Yi Ren |
| author_sort | Ying Li |
| collection | DOAJ |
| description | This study investigates the metallicity distribution in M31 and M33 by using the near-infrared color index J − K of the tip of the red giant branch (TRGB) of the member stars from Y. Ren et al. after removing foreground dwarf stars by a near-infrared J − H versus H − K diagram as well as Gaia astrometric measurements. We employ the Voronoi binning technique to divide the galaxy into subregions, the Poisson noise method to determine the TRGB position in the J − K versus K diagram, and the bootstrap method to estimate uncertainties. The TRGB positions are calculated to be J − K = 1.195 ± 0.002 and 1.100 ± 0.003, and K = 17.615 ± 0.007 and 18.185 ± 0.053 for M31 and M33, respectively, consistent with previous results. The J − K gradient of M31 is found to be −0.0055 kpc ^−1 at R _GC = (0, 24) kpc and −0.0002 kpc ^−1 at R _GC = (24, 150) kpc. Notably, two dust rings are evident at 11.5 and 14.5 kpc, in agreement with previous studies. The J − K of M33 is analyzed in four directions and generally shows a trend of gradually decreasing from the inside to the outside, however, it shows an increasing trend of 0.022 kpc ^−1 in the inner 0–2 kpc in the west. Through the color–metallicity relation of the TRGB, the metallicity gradient of M31 is −0.040 ± 0.0012 dex kpc ^−1 for R _GC < 30 kpc and −0.001 ± 0.0002 dex kpc ^−1 for R _GC > 30 kpc, and for M33, it is −0.269 ± 0.0206 dex kpc ^−1 for R _GC < 9 kpc. |
| format | Article |
| id | doaj-art-c7eb99fe62d64a578fd7548472579b3c |
| institution | OA Journals |
| issn | 1538-3881 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astronomical Journal |
| spelling | doaj-art-c7eb99fe62d64a578fd7548472579b3c2025-08-20T02:07:20ZengIOP PublishingThe Astronomical Journal1538-38812025-01-011701210.3847/1538-3881/add14eMetallicity Distribution in M31 and M33 Based on the Tip of the Red Giant Branch Near-infrared ColorYing Li0https://orcid.org/0009-0001-5020-4269Biwei Jiang1https://orcid.org/0000-0003-3168-2617Yi Ren2https://orcid.org/0000-0003-1218-8699Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University , Beijing 102206, People’s Republic of China ; bjiang@bnu.edu.cn; School of Physics and Astronomy, Beijing Normal University , Beijing 100875, People’s Republic of ChinaInstitute for Frontiers in Astronomy and Astrophysics, Beijing Normal University , Beijing 102206, People’s Republic of China ; bjiang@bnu.edu.cn; School of Physics and Astronomy, Beijing Normal University , Beijing 100875, People’s Republic of ChinaCollege of Physics and Electronic Engineering, Qilu Normal University , Jinan 250200, People’s Republic of ChinaThis study investigates the metallicity distribution in M31 and M33 by using the near-infrared color index J − K of the tip of the red giant branch (TRGB) of the member stars from Y. Ren et al. after removing foreground dwarf stars by a near-infrared J − H versus H − K diagram as well as Gaia astrometric measurements. We employ the Voronoi binning technique to divide the galaxy into subregions, the Poisson noise method to determine the TRGB position in the J − K versus K diagram, and the bootstrap method to estimate uncertainties. The TRGB positions are calculated to be J − K = 1.195 ± 0.002 and 1.100 ± 0.003, and K = 17.615 ± 0.007 and 18.185 ± 0.053 for M31 and M33, respectively, consistent with previous results. The J − K gradient of M31 is found to be −0.0055 kpc ^−1 at R _GC = (0, 24) kpc and −0.0002 kpc ^−1 at R _GC = (24, 150) kpc. Notably, two dust rings are evident at 11.5 and 14.5 kpc, in agreement with previous studies. The J − K of M33 is analyzed in four directions and generally shows a trend of gradually decreasing from the inside to the outside, however, it shows an increasing trend of 0.022 kpc ^−1 in the inner 0–2 kpc in the west. Through the color–metallicity relation of the TRGB, the metallicity gradient of M31 is −0.040 ± 0.0012 dex kpc ^−1 for R _GC < 30 kpc and −0.001 ± 0.0002 dex kpc ^−1 for R _GC > 30 kpc, and for M33, it is −0.269 ± 0.0206 dex kpc ^−1 for R _GC < 9 kpc.https://doi.org/10.3847/1538-3881/add14eMetallicityRed giant tipAndromeda galaxyTriangulum Galaxy |
| spellingShingle | Ying Li Biwei Jiang Yi Ren Metallicity Distribution in M31 and M33 Based on the Tip of the Red Giant Branch Near-infrared Color The Astronomical Journal Metallicity Red giant tip Andromeda galaxy Triangulum Galaxy |
| title | Metallicity Distribution in M31 and M33 Based on the Tip of the Red Giant Branch Near-infrared Color |
| title_full | Metallicity Distribution in M31 and M33 Based on the Tip of the Red Giant Branch Near-infrared Color |
| title_fullStr | Metallicity Distribution in M31 and M33 Based on the Tip of the Red Giant Branch Near-infrared Color |
| title_full_unstemmed | Metallicity Distribution in M31 and M33 Based on the Tip of the Red Giant Branch Near-infrared Color |
| title_short | Metallicity Distribution in M31 and M33 Based on the Tip of the Red Giant Branch Near-infrared Color |
| title_sort | metallicity distribution in m31 and m33 based on the tip of the red giant branch near infrared color |
| topic | Metallicity Red giant tip Andromeda galaxy Triangulum Galaxy |
| url | https://doi.org/10.3847/1538-3881/add14e |
| work_keys_str_mv | AT yingli metallicitydistributioninm31andm33basedonthetipoftheredgiantbranchnearinfraredcolor AT biweijiang metallicitydistributioninm31andm33basedonthetipoftheredgiantbranchnearinfraredcolor AT yiren metallicitydistributioninm31andm33basedonthetipoftheredgiantbranchnearinfraredcolor |