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

HD 177620


내용

사진

사진 업로드

DSS Images   Other Images


관련 글

Ultraviolet Imaging Telescope Near-Ultraviolet Bright Object Catalog
We present a photometric catalog of 2244 objects detected by theUltraviolet Imaging Telescope in the near-ultraviolet (NUV; 1650A <λ < 2900 A) during the Astro Space Shuttle mission. Sources inthe catalog are as faint as m_nuv_ ~ 18.8, or f_nuv_ ~ 1.1 x 10^16^ ergss^-1^ cm^-2^ A^-1^, but the survey is not complete to this level.Optical catalogs were used to cross identify sources and derive NUV - Vcolors. A majority of the objects (88%) do indeed have proposed opticalidentifications from catalogs, and most are stars. Our purpose increating the catalog is to form a database useful for identifying veryblue objects and performing Galactic UV stellar population studies.

A magnitude limited stellar X-ray survey and the F star X-ray luminosity function
An X-ray survey has been conducted of stars brighter than visualmagnitude 8.5 that have serendipitously fallen into the fields of viewof the Imaging Proportional Counter of the Einstein Observatory. Thesurvey includes 227 separate 1 x 1 deg fields, containing 274 stars witha visual magnitude of no more than 8.5 and covering a wide range ofspectral types and luminosity classes. X-ray emission was detected from33 stars, and upper limits have been determined for the remainder of thesample. F type stars dominate the detected sample, and most of these areshown to be dwarfs. An X-ray luminosity function for dF stars has beendeduced, and reveals that the average 0.2-4.0 keV luminosity of thesestars is around 10 to the 29th erg/sec. Constraints have been placed onthe high luminosity tails and medians of the X-ray luminosity functionsfor other types of stars.

Results from an extensive Einstein stellar survey
The preliminary results of the Einstein Observatory stellar X-ray surveyare presented. To date, 143 soft X-ray sources have been identified withstellar counterparts, leaving no doubt that stars in general constitutea pervasive class of low-luminosity galactic X-ray sources. Stars alongthe entire main sequence, of all luminosity classes, pre-main sequencestars as well as very evolved stars have been detected. Early type OBstars have X-ray luminosities in the range 10 to the 31st to 10 to the34th ergs/s; late type stars show a somewhat lower range of X-rayemission levels, from 10 to the 26th to 10 to the 31st ergs/s. Late typemain-sequence stars show little dependence of X-ray emission levels uponstellar effective temperature; similarly, the observations suggest weak,if any, dependence of X-ray luminosity upon effective gravity. Instead,the data show a broad range of emission levels (about three orders ofmagnitude) throughout the main sequence later than F0.

새 글 등록


관련 링크

  • - 링크가 없습니다. -
새 링크 등록


다음 그룹에 속해있음:


관측 및 측정 데이터

별자리:용자리
적경:18h59m28.74s
적위:+70°41'50.1"
가시등급:7.902
거리:207.469 파섹
적경상의 고유운동:-0.2
적위상의 고유운동:-25
B-T magnitude:9.055
V-T magnitude:7.998

천체목록:
일반명   (Edit)
HD 1989HD 177620
TYCHO-2 2000TYC 4435-43-1
USNO-A2.0USNO-A2 1575-04081730
HIPHIP 93237

→ VizieR에서 더 많은 목록을 가져옵니다.