I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance Scale
In the I -band color–magnitude diagrams of resolved nearby galaxies, the reddest asymptotic giant branch ( AGB ) stars form a previously unremarked-upon, but nevertheless distinct and easily identified population of high-luminosity stars. Hereafter we refer to this population as being comprised of I...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2025-01-01
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| Series: | The Astronomical Journal |
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| Online Access: | https://doi.org/10.3847/1538-3881/ada3d4 |
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| author | Barry F. Madore Wendy L. Freedman Taylor Hoyt In Sung Jang Abigail J. Lee Kayla A. Owens |
| author_facet | Barry F. Madore Wendy L. Freedman Taylor Hoyt In Sung Jang Abigail J. Lee Kayla A. Owens |
| author_sort | Barry F. Madore |
| collection | DOAJ |
| description | In the I -band color–magnitude diagrams of resolved nearby galaxies, the reddest asymptotic giant branch ( AGB ) stars form a previously unremarked-upon, but nevertheless distinct and easily identified population of high-luminosity stars. Hereafter we refer to this population as being comprised of I-band AGB ( IAGB ) stars. Identifying these stars in the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and in NGC 4258 (for all three of which there are published geometric distances) we find that the marginalized luminosity functions are each well approximated by single-peaked Gaussians, having 1 σ dispersions of ±0.22 mag, ±0.25 mag and ±0.24 mag, respectively. The zero points for the modal I -band absolute magnitudes of IAGB stars are found to be M _I = −4.49 ± 0.003 mag (stat) in the LMC (4204 stars), M _I = −4.67 ± 0.008 mag (stat), for the SMC sample (916 stars), and M _I = −4.78 ± 0.030 mag (stat) for NGC 4258 (62 stars). A global average over these three independent calibrations of the IAGB zero-point (weighted inversely by squares of their systematic errors) gives 〈 M _I 〉 = −4.65 ± 0.119 mag (stat) ± 0.025 (sys). In Paper II we will show the results of applying the IAGB Method to 92 galaxies additional galaxies resolved by Hubble Space Telescope, reaching out to distances just short of 10 Mpc. |
| first_indexed | 2025-03-14T15:27:33Z |
| format | Article |
| id | doaj.art-09414b76f9c546a6b0298313c0d39549 |
| institution | Directory Open Access Journal |
| issn | 1538-3881 |
| language | English |
| last_indexed | 2025-03-14T15:27:33Z |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astronomical Journal |
| spelling | doaj.art-09414b76f9c546a6b0298313c0d395492025-02-25T07:59:56ZengIOP PublishingThe Astronomical Journal1538-38812025-01-01169316210.3847/1538-3881/ada3d4I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance ScaleBarry F. Madore0Wendy L. Freedman1https://orcid.org/0000-0003-3431-9135Taylor Hoyt2https://orcid.org/0000-0001-9664-0560In Sung Jang3https://orcid.org/0000-0002-2502-0070Abigail J. Lee4https://orcid.org/0000-0002-5865-0220Kayla A. Owens5https://orcid.org/0000-0003-3339-8820Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101, USA; Department of Astronomy & Astrophysics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USA ; wfreedman@uchicago.eduDepartment of Astronomy & Astrophysics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USA ; wfreedman@uchicago.edu; Kavli Institute for Cosmological Physics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USADepartment of Astronomy & Astrophysics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USA ; wfreedman@uchicago.eduDepartment of Astronomy & Astrophysics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USA ; wfreedman@uchicago.edu; Kavli Institute for Cosmological Physics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USADepartment of Astronomy & Astrophysics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USA ; wfreedman@uchicago.edu; Kavli Institute for Cosmological Physics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USADepartment of Astronomy & Astrophysics, University of Chicago , 5640 South Ellis Avenue, Chicago, IL 60637, USA ; wfreedman@uchicago.eduIn the I -band color–magnitude diagrams of resolved nearby galaxies, the reddest asymptotic giant branch ( AGB ) stars form a previously unremarked-upon, but nevertheless distinct and easily identified population of high-luminosity stars. Hereafter we refer to this population as being comprised of I-band AGB ( IAGB ) stars. Identifying these stars in the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and in NGC 4258 (for all three of which there are published geometric distances) we find that the marginalized luminosity functions are each well approximated by single-peaked Gaussians, having 1 σ dispersions of ±0.22 mag, ±0.25 mag and ±0.24 mag, respectively. The zero points for the modal I -band absolute magnitudes of IAGB stars are found to be M _I = −4.49 ± 0.003 mag (stat) in the LMC (4204 stars), M _I = −4.67 ± 0.008 mag (stat), for the SMC sample (916 stars), and M _I = −4.78 ± 0.030 mag (stat) for NGC 4258 (62 stars). A global average over these three independent calibrations of the IAGB zero-point (weighted inversely by squares of their systematic errors) gives 〈 M _I 〉 = −4.65 ± 0.119 mag (stat) ± 0.025 (sys). In Paper II we will show the results of applying the IAGB Method to 92 galaxies additional galaxies resolved by Hubble Space Telescope, reaching out to distances just short of 10 Mpc.https://doi.org/10.3847/1538-3881/ada3d4Carbon starsLate-type giant starsDistance indicators |
| spellingShingle | Barry F. Madore Wendy L. Freedman Taylor Hoyt In Sung Jang Abigail J. Lee Kayla A. Owens I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance Scale The Astronomical Journal Carbon stars Late-type giant stars Distance indicators |
| title | I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance Scale |
| title_full | I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance Scale |
| title_fullStr | I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance Scale |
| title_full_unstemmed | I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance Scale |
| title_short | I-band Asymptotic Giant Branch Stars. I. Exploring a New Standard Candle for the Extragalactic Distance Scale |
| title_sort | i band asymptotic giant branch stars i exploring a new standard candle for the extragalactic distance scale |
| topic | Carbon stars Late-type giant stars Distance indicators |
| url | https://doi.org/10.3847/1538-3881/ada3d4 |
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