KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006
Blue large-amplitude pulsators (BLAPs), a recently classified type of variable stars, are evolved objects likely formed through interactions between stars in a binary system. However, only two BLAPs with stellar companions have been discovered to date. This paper presents photometric data from the K...
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2025-01-01
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| Series: | The Astronomical Journal |
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| Online Access: | https://doi.org/10.3847/1538-3881/adc4e4 |
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| author | Seung-Lee Kim Chung-Uk Lee Kyeongsoo Hong Jae Woo Lee Dong-Jin Kim Sang-Mok Cha Yongseok Lee Dong-Joo Lee Byeong-Gon Park |
| author_facet | Seung-Lee Kim Chung-Uk Lee Kyeongsoo Hong Jae Woo Lee Dong-Jin Kim Sang-Mok Cha Yongseok Lee Dong-Joo Lee Byeong-Gon Park |
| author_sort | Seung-Lee Kim |
| collection | DOAJ |
| description | Blue large-amplitude pulsators (BLAPs), a recently classified type of variable stars, are evolved objects likely formed through interactions between stars in a binary system. However, only two BLAPs with stellar companions have been discovered to date. This paper presents photometric data from the Korea Microlensing Telescope Network (KMTNet) for three BLAPs located in the direction of the Galactic bulge: OGLE-BLAP-006, OGLE-BLAP-007, and OGLE-BLAP-009. The data were collected over eight consecutive years, beginning in 2016, with a high cadence of approximately 15 minutes. Frequency analysis of light variations revealed OGLE-BLAP-006 as a multimode pulsator with a dominant frequency of 37.88 day ^−1 and two new frequencies of 38.25 and 35.05 day ^−1 . In contrast, OGLE-BLAP-007 and OGLE-BLAP-009 exhibit single-mode pulsation. By combining the KMTNet data with archival OGLE observations, we investigated pulsation timing variations of the BLAPs using an O − C diagram to identify the light travel time effect caused by the orbital motion of their companions. We found that OGLE-BLAP-006, with no evidence of close companions, has two wide-orbit companions with orbital periods of approximately 4700 and 6300 days, making it the third known BLAP in a stellar system; however, no companions were found for OGLE-BLAP-007 and OGLE-BLAP-009. Furthermore, we identified seven other BLAP candidates with wide companions using OGLE data, suggesting that such systems are relatively common. We propose that a BLAP with a wide companion may be a merger remnant of an inner close binary within a hierarchical triple system. |
| format | Article |
| id | doaj-art-efdb503de3e341398b2dc3bff2292a09 |
| 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-efdb503de3e341398b2dc3bff2292a092025-08-20T02:12:45ZengIOP PublishingThe Astronomical Journal1538-38812025-01-01169526110.3847/1538-3881/adc4e4KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006Seung-Lee Kim0https://orcid.org/0000-0003-0562-5643Chung-Uk Lee1https://orcid.org/0000-0003-0043-3925Kyeongsoo Hong2https://orcid.org/0000-0002-8692-2588Jae Woo Lee3https://orcid.org/0000-0002-5739-9804Dong-Jin Kim4https://orcid.org/0000-0002-4292-9649Sang-Mok Cha5https://orcid.org/0000-0002-7511-2950Yongseok Lee6https://orcid.org/0000-0001-7594-8072Dong-Joo Lee7https://orcid.org/0009-0000-5737-0908Byeong-Gon Park8https://orcid.org/0000-0002-6982-7722Korea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.krKorea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.krKorea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.krKorea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.krKorea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.krKorea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.kr; School of Space Research, Kyung Hee University , Yongin 17104, Republic of KoreaKorea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.kr; School of Space Research, Kyung Hee University , Yongin 17104, Republic of KoreaKorea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.kr; Department of Astronomy and Space Science, Chungbuk National University , Cheongju 28644, Republic of KoreaKorea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea ; slkim@kasi.re.krBlue large-amplitude pulsators (BLAPs), a recently classified type of variable stars, are evolved objects likely formed through interactions between stars in a binary system. However, only two BLAPs with stellar companions have been discovered to date. This paper presents photometric data from the Korea Microlensing Telescope Network (KMTNet) for three BLAPs located in the direction of the Galactic bulge: OGLE-BLAP-006, OGLE-BLAP-007, and OGLE-BLAP-009. The data were collected over eight consecutive years, beginning in 2016, with a high cadence of approximately 15 minutes. Frequency analysis of light variations revealed OGLE-BLAP-006 as a multimode pulsator with a dominant frequency of 37.88 day ^−1 and two new frequencies of 38.25 and 35.05 day ^−1 . In contrast, OGLE-BLAP-007 and OGLE-BLAP-009 exhibit single-mode pulsation. By combining the KMTNet data with archival OGLE observations, we investigated pulsation timing variations of the BLAPs using an O − C diagram to identify the light travel time effect caused by the orbital motion of their companions. We found that OGLE-BLAP-006, with no evidence of close companions, has two wide-orbit companions with orbital periods of approximately 4700 and 6300 days, making it the third known BLAP in a stellar system; however, no companions were found for OGLE-BLAP-007 and OGLE-BLAP-009. Furthermore, we identified seven other BLAP candidates with wide companions using OGLE data, suggesting that such systems are relatively common. We propose that a BLAP with a wide companion may be a merger remnant of an inner close binary within a hierarchical triple system.https://doi.org/10.3847/1538-3881/adc4e4Stellar pulsationsBlue large-amplitude pulsatorsTiming variation methodsMultiple starsStellar evolution |
| spellingShingle | Seung-Lee Kim Chung-Uk Lee Kyeongsoo Hong Jae Woo Lee Dong-Jin Kim Sang-Mok Cha Yongseok Lee Dong-Joo Lee Byeong-Gon Park KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006 The Astronomical Journal Stellar pulsations Blue large-amplitude pulsators Timing variation methods Multiple stars Stellar evolution |
| title | KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006 |
| title_full | KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006 |
| title_fullStr | KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006 |
| title_full_unstemmed | KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006 |
| title_short | KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge. I. Discovery of Wide-orbit Companions in OGLE-BLAP-006 |
| title_sort | kmtnet view of blue large amplitude pulsators toward the galactic bulge i discovery of wide orbit companions in ogle blap 006 |
| topic | Stellar pulsations Blue large-amplitude pulsators Timing variation methods Multiple stars Stellar evolution |
| url | https://doi.org/10.3847/1538-3881/adc4e4 |
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