A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary
The symbiotic X-ray binary Sct X-1 was suggested to be the first known neutron star accreting from a red supergiant companion. Although known for nearly 50 yr, detailed characterization of the donor remains lacking, particularly due to the extremely high reddening toward the source (AV ≳ 25 mag). He...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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American Astronomical Society
2022
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| Online Access: | https://hdl.handle.net/1721.1/142205 |
| _version_ | 1811071930652950528 |
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| author | De, Kishalay Chakrabarty, Deepto Soria, Roberto Ashley, Michael CB Conroy, Charlie Hankins, Matthew J Kasliwal, Mansi M Lau, Ryan M Moore, Anna M Simcoe, Robert Soon, Jamie Travouillon, Tony |
| author_facet | De, Kishalay Chakrabarty, Deepto Soria, Roberto Ashley, Michael CB Conroy, Charlie Hankins, Matthew J Kasliwal, Mansi M Lau, Ryan M Moore, Anna M Simcoe, Robert Soon, Jamie Travouillon, Tony |
| author_sort | De, Kishalay |
| collection | MIT |
| description | The symbiotic X-ray binary Sct X-1 was suggested to be the first known neutron star accreting from a red supergiant companion. Although known for nearly 50 yr, detailed characterization of the donor remains lacking, particularly due to the extremely high reddening toward the source (AV ≳ 25 mag). Here, we present (i) improved localization of the counterpart using Gaia and Chandra observations, (ii) the first broadband infrared spectrum (≈1–5 μm; R ≈ 2000) obtained with SpeX on the NASA Infrared Telescope Facility, and (iii) the J-band light curve from the Palomar Gattini-IR survey. The infrared spectrum is characterized by (i) deep water absorption features (H2O index ≈ 40%), (ii) strong TiO, VO, and CO features, and (iii) weak/absent CN lines. We show that these features are inconsistent with known red supergiants but suggest an M8-9 III–type O-rich Mira donor star. We report the discovery of large-amplitude (ΔJ ≈ 3.5 mag) periodic photometric variability, suggesting a pulsation period of 621 ± 36 (systematic) ± 8 (statistical) days, which we use to constrain the donor to be a relatively luminous Mira (MK = −8.6 ± 0.3 mag) at a distance of ${3.6}_{-0.7}^{+0.8}$ kpc. Comparing these characteristics to recent models, we find the donor to be consistent with a ≈3–5 M⊙ star at an age of ≈0.1–0.3 Gyr. Together, we show that Sct X-1 was previously misclassified as an evolved high-mass X-ray binary; instead, it is an intermediate-mass system with the first confirmed Mira donor in an X-ray binary. We discuss the implications of Mira donors in symbiotic X-ray binaries and highlight the potential of wide-field infrared time-domain surveys and broadband infrared spectroscopy to unveil their demographics. |
| first_indexed | 2024-09-23T08:58:14Z |
| format | Article |
| id | mit-1721.1/142205 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:58:14Z |
| publishDate | 2022 |
| publisher | American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/1422052022-05-01T03:38:45Z A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary De, Kishalay Chakrabarty, Deepto Soria, Roberto Ashley, Michael CB Conroy, Charlie Hankins, Matthew J Kasliwal, Mansi M Lau, Ryan M Moore, Anna M Simcoe, Robert Soon, Jamie Travouillon, Tony The symbiotic X-ray binary Sct X-1 was suggested to be the first known neutron star accreting from a red supergiant companion. Although known for nearly 50 yr, detailed characterization of the donor remains lacking, particularly due to the extremely high reddening toward the source (AV ≳ 25 mag). Here, we present (i) improved localization of the counterpart using Gaia and Chandra observations, (ii) the first broadband infrared spectrum (≈1–5 μm; R ≈ 2000) obtained with SpeX on the NASA Infrared Telescope Facility, and (iii) the J-band light curve from the Palomar Gattini-IR survey. The infrared spectrum is characterized by (i) deep water absorption features (H2O index ≈ 40%), (ii) strong TiO, VO, and CO features, and (iii) weak/absent CN lines. We show that these features are inconsistent with known red supergiants but suggest an M8-9 III–type O-rich Mira donor star. We report the discovery of large-amplitude (ΔJ ≈ 3.5 mag) periodic photometric variability, suggesting a pulsation period of 621 ± 36 (systematic) ± 8 (statistical) days, which we use to constrain the donor to be a relatively luminous Mira (MK = −8.6 ± 0.3 mag) at a distance of ${3.6}_{-0.7}^{+0.8}$ kpc. Comparing these characteristics to recent models, we find the donor to be consistent with a ≈3–5 M⊙ star at an age of ≈0.1–0.3 Gyr. Together, we show that Sct X-1 was previously misclassified as an evolved high-mass X-ray binary; instead, it is an intermediate-mass system with the first confirmed Mira donor in an X-ray binary. We discuss the implications of Mira donors in symbiotic X-ray binaries and highlight the potential of wide-field infrared time-domain surveys and broadband infrared spectroscopy to unveil their demographics. 2022-04-29T16:30:18Z 2022-04-29T16:30:18Z 2022-03-01 2022-04-29T16:27:17Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/142205 De, Kishalay, Chakrabarty, Deepto, Soria, Roberto, Ashley, Michael CB, Conroy, Charlie et al. 2022. "A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary." The Astrophysical Journal Letters, 928 (1). en 10.3847/2041-8213/ac5b11 The Astrophysical Journal Letters Creative Commons Attribution 4.0 International License https://creativecommons.org/licenses/by/4.0 application/pdf American Astronomical Society American Astronomical Society |
| spellingShingle | De, Kishalay Chakrabarty, Deepto Soria, Roberto Ashley, Michael CB Conroy, Charlie Hankins, Matthew J Kasliwal, Mansi M Lau, Ryan M Moore, Anna M Simcoe, Robert Soon, Jamie Travouillon, Tony A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary |
| title | A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary |
| title_full | A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary |
| title_fullStr | A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary |
| title_full_unstemmed | A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary |
| title_short | A Massive AGB Donor in Scutum X-1: Identification of the First Mira Variable in an X-Ray Binary |
| title_sort | massive agb donor in scutum x 1 identification of the first mira variable in an x ray binary |
| url | https://hdl.handle.net/1721.1/142205 |
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