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. Episodic mass-loss events such as giant eruptions in luminous blue variables or pre-supernova eruptions in red supergiants drastically alter the evolutionary path of a massive star, resulting in a rich and complex circumstellar environment and IR excess. However, the incidence of these events, and hence their importance in massive star evolution, remains unknown. Aims. The ASSESS project (Episodic Mass Loss in Evolved Massive Stars: Key to Understanding the Explosive early Universe) aims to determine the role of episodic mass loss in the evolution of massive stars. As a first step, we constructed a catalog of spectroscopically identified dusty, evolved massive stars in ten southern galaxies for which Spitzer point-source catalogs are available. The resulting catalog may be used to identify stars that have undergone an episodic mass-loss event. The target galaxies span a range of metallicities, Z = 0.06–1.6 Z ⊙ , allowing for the investigation of a potential metallicity dependence. Methods. We conducted multi-object spectroscopy of dusty massive star candidates in ten target galaxies using the Very Large Telescope. We obtained 763 spectra from WLM, NGC 55, NGC 247, NGC 253, NGC 300, NGC 1313, NGC 3109, Sextans A, M83, and NGC 7793. The targets were selected using their Spitzer photometry, by prioritizing targets with a strong IR excess, which indicates the presence of hot dust. We determined a spectral classification for each target. Additionally, we used archival images from the Hubble Space Telescope (HST), available for 150 of our targets, to provide a visual classification for 80 targets, as a star, cluster, or galaxy. Results. We provide a catalog of 541 spectroscopically classified sources that includes 185 massive stars, of which 154 are newly classified massive stars. The catalog contains 129 red supergiants, 27 blue supergiants, 10 yellow supergiants, 4 luminous blue variable candidates, 7 supergiant B[e] stars, and 8 emission-line objects. Evidence for circumstellar dust is found in 24% of these massive stars, based on their IR colors. We report a success rate of 28% for identifying massive stars from our observed spectra, while the average success rate of our priority system for selecting evolved massive stars is 36%. Additionally, the catalog contains 21 background galaxies (including active galactic nuclei and quasars), 10 carbon stars, and 99 H II regions. We measured the line ratios [N II ]/Hα and [S II ]/Hα for 76 H II regions and 36 other spectra with nebular emission lines, thereby identifying eight sources with shocked emission. Conclusions. We present the largest catalog of evolved massive stars and in particular of red supergiants in nearby galaxies at low Z beyond the Local Group. The brightest and reddest of these are candidates for episodic mass loss. The fraction of dusty massive stars observed with respect to the initial selection is ~30%. We expect this catalog to trigger follow-up studies and pave the way for a comprehensive study of the eruptive late stages of massive star evolution in the era of the James Webb Space Telescope and the new survey telescopes (e.g., the Euclid mission, Nancy Grace Roman Space Telescope, and Vera C. Rubin Observatory).
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
