내용
사진
사진 업로드
DSS Images Other Images
관련 글
The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
| Further optical and UV spectroscopy of stars in the direction of the Riegel & Crutcher cold cloud
Further optical and UV spectral data are presented for four stars in thedirection of the Riegel & Crutcher cold cloud. Two of the stars lieclose in position to the area covered by our previous optical, UV andradio studies near l=10 deg, while the other two stars lie near l=15deg. The stars range in distance from about 140 pc to 1.5 kpc. The RCcold cloud gas is detected (at a velocity of ~+3 km s^-1) towards a starat a distance of about 150 pc, in agreement with previous cloud distanceestimates. The spectra of the more distant stars contain components athigher velocities; components at +20 and +40 km s^-1 may be identifiedwith peculiar-velocity gas associated with the Sagittarius arm, seenelsewhere in the general field, while a component at -60 km s^-1 may bestellar or interstellar in nature. A component at -20 km s^-1 seentowards previously studied stars in the field is not clearly identifiedin the spectra of the present stars. The atomic column densities of theRiegel & Crutcher cloud component do not vary greatly across thefield, although the CH and CH^+ column densities are more variable. TheCH/CH^+ column density ratio remains fairly constant, however, at avalue that is consistent with the CH^+ being formed in a warm boundarylayer. Along the HD 167264 sightline, the cold gas has an electrondensity of the order of 0.05-0.1 cm^-3 and a space density of the orderof 100-300 cm^-3.
| Optical and UV spectroscopy of stars in the direction of the Riegel & Crutcher cold cloud
Optical and UV spectral data are presented for the stars HD 165202,168708 which lie in the direction of the Riegel & Crutcher coldcloud. These observations complement our earlier studies in whichhigh-resolution HI profiles mapped the cold cloud in self-absorption(Montgomery et al.). HD 165202 lies in a direction close to where weobserve a maximum HI self-absorption column density and HD 168708 liestowards the edge of the cold cloud; from their spectra we determine thestellar distances to be ~=200 and 430 pc, respectively. We show that theHI column densities associated with the cold core represent some 3-10per cent of the total HI gas column observed towards the two stars. Wesuggest that the cloud core is embedded in diffuse, cold HI gas and thatthe sightlines contain a warm, intercloud medium; the gas observed inCH^+ may be produced in a thin interface between molecular gas of thecold cloud and the warm medium. Whilst it is not possible to obtain adetailed description of these sightlines, the evidence points to arelatively dense cloud core of space density ~=100-200 cm^-3 andthickness <=1 pc.
| Absolute Emission Line Intensities of Planetary Nebulae. II.
Not Available
|
새 글 등록
관련 링크
새 링크 등록
다음 그룹에 속해있음:
|
관측 및 측정 데이터
천체목록:
|
INHABITED SKY
