인문학
사회과학
자연과학
공학
의약학
농수해양학
예술체육학
복합학
DBpia AI
AI 에이전트
AI 아이디어
AI 리더
AI 뷰어
Citeasy
크롬 서지관리 다운로드
지원사업
학술연구/단체지원/교육 등 연구자 활동을 지속하도록 DBpia가 지원하고 있어요.
커뮤니티
연구자들이 자신의 연구와 전문성을 널리 알리고, 새로운 협력의 기회를 만들 수 있는 네트워킹 공간이에요.
초록·키워드
Context . Asymptotic giant branch (AGB) stars are not expected to be X-ray-emitters, yet a small fraction of them, the so-called X-AGBs, show X-ray emission that can be attributed to coronal activity of a companion or accretion onto one. Aims . By searching the recently released SRG eROSITA-DE eRASS1 source catalog, we aim to increase the sample of known X-AGBs and investigate their X-ray and far-UV properties. So far, 36 X-AGBs have been reported, which includes 21 previous detections from ROSAT RASS, Chandra, and XMM-Newton and 15 recent detections from eROSITA eRASS1. Methods . We cross-correlated the position of sources in the eROSITA-DE eRASS1 catalog with the largest available samples of AGB stars in order to find possible X-ray counterparts. We carefully checked the possible counterparts by comparing X-ray and near-IR K images, disregarding those affected by optical loading, those found to be diffuse sources, or those simply considered unreliable positional associations. Results . We have found seven high-confidence X-AGBs and another seven possible ones. Accounting for previous X-ray detections, the sample of X-AGBs is increased by 11 new sources, increasing the sample of X-AGBs from 36 up to 47. Adding these sources to previous eROSITA-DE eRASS1 X-AGB detections, eROSITA has so far discovered 26 new X-AGBs, more than doubling the number of known X-AGBs. This demonstrates eROSITA’s capability to detect X-AGBs despite the challenge posed by the optical loading caused by their near-IR brightness, which makes the X-ray detection untrustworthy in a number of cases. Conclusions . The eRASS1 X-AGBs tend to have a higher X-ray luminosity than that of previously detected X-AGBs, suggesting a bias toward brighter sources that is very likely due to the short exposure time of eRASS1 sources. A comparison of the X-ray and far-UV luminosity of X-AGBs with those of X-ray-emitter symbiotic stars (X-SySts) revealed an overlap in the X-ray luminosity range 10 29.5 < L X (erg s −1 ) <10 33.0 . The average higher X-ray luminosity of X-SySts AGBs (≈10 32 erg s −1 ) can be interpreted as X-ray emission arising from a boundary layer between an accretion disk and a white dwarf, whereas the average lower X-ray luminosity (≈5 × 10 30 erg s −1 ) of X-AGBs would arise from an accretion disk around main-sequence or subgiant F-K companion stars.
인공지능 문자 인식 모델을 통해 추출된 텍스트로, 일부 오타나 오류가 포함될 수 있으나 지속적으로 개선 중입니다.
오류를 발견하셨다면 해당 부분을 드래그한 후 ' 를 통해 신고해주세요.
오류를 발견하셨다면 해당 부분을 드래그한 후 ' 를 통해 신고해주세요.
최근 본 자료 전체보기
