시작하기     To Survive in the Universe    
Inhabited Sky
    News@Sky     천체사진     컬렉션     포럼     Blog New!     질문및답변     출판     로그인  

HD 76927


내용

사진

사진 업로드

DSS Images   Other Images


관련 글

Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog
We complete construction of a catalog containing improved astrometry andnew optical/infrared photometry for the vast majority of NLTT starslying in the overlap of regions covered by POSS I and by the secondincremental Two Micron All Sky Survey (2MASS) release, approximately 44%of the sky. The epoch 2000 positions are typically accurate to 130 mas,the proper motions to 5.5 mas yr-1, and the V-J colors to0.25 mag. Relative proper motions of binary components are measured to 3mas yr-1. The false-identification rate is ~1% for11<~V<~18 and substantially less at brighter magnitudes. Theseimprovements permit the construction of a reduced proper-motion diagramthat, for the first time, allows one to classify NLTT stars intomain-sequence (MS) stars, subdwarfs (SDs), and white dwarfs (WDs). We inturn use this diagram to analyze the properties of both our catalog andthe NLTT catalog on which it is based. In sharp contrast to popularbelief, we find that NLTT incompleteness in the plane is almostcompletely concentrated in MS stars, and that SDs and WDs are detectedalmost uniformly over the sky δ>-33deg. Our catalogwill therefore provide a powerful tool to probe these populationsstatistically, as well as to reliably identify individual SDs and WDs.

The photometric variability of solar-type stars. II - Stars selected from Wilson's chromospheric activity survey
Eleven solar-type main-sequence stars have been observed to search forcontinuum variability. Stars were selected from Wilson's chromosphericactivity survey, and were observed for periods of three to six monthswith intermediate-band Stroemgren uvby photometry. Evidence is foundthat two of these eleven stars are variable and that one other may be.Comparison with contemporaneous Ca II H + K emission flux measurementsshows that the amplitude of photometric variability correlates stronglywith both the mean emission flux and the amplitude of its variation.Variations in continuum light and emission flux tend to correlate intime, as well, with continuum minima coinciding with emission maxima andvice-versa. It is inferred that the surface activity of these starstends to be confined to localized activity centers that include bothemission plages and dark spots, similar to the active regions observedon the sun.

새 글 등록


관련 링크

  • - 링크가 없습니다. -
새 링크 등록


다음 그룹에 속해있음:


관측 및 측정 데이터

별자리:바다뱀자리
적경:08h59m08.21s
적위:-05°50'35.0"
가시등급:8.564
거리:96.993 파섹
적경상의 고유운동:-74.2
적위상의 고유운동:143.9
B-T magnitude:9.169
V-T magnitude:8.614

천체목록:
일반명   (Edit)
HD 1989HD 76927
TYCHO-2 2000TYC 4877-1551-1
USNO-A2.0USNO-A2 0825-06662377
HIPHIP 44119

→ VizieR에서 더 많은 목록을 가져옵니다.