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Ýlgili Makaleler
Spectropolarimetry and Radiative Transfer Modeling of Three Proto-Planetary Nebulae
We measured the spectrum of polarization for three proto-planetarynebulae (PPNs), IRAS 17411-2411, IRAS 08005-2356, and IRAS 04296+3429,and made model calculations with the dust-scattering Monte Carlo codeDIRTY and the dust emission code 2Dust. We show that high levels ofpolarization in these PPNs correlate with extreme asymptotic giantbranch (AGB) superwind mass-loss rates in excess of 10-4Msolar yr-1. All three objects show evidence forevacuated lobes cleared by collimated fast winds, and two indicate asignificant equatorial mass enhancement. Our best-fit models requiresharply peaked grain size distributions, suggesting that most of thelight is being scattered by grains of a characteristic size in IRAS17441-2411 and IRAS 08005-2356. IRAS 17441-2411 and IRAS 08005-2356 havelobes with wide opening angles, perhaps produced by deflection of apolar jet from an accreting companion by the AGB superwind. Modeling thespectropolarimetry of IRAS 04296+3429 indicates a point-symmetric,multipolar morphology in the PPN phase. The modeling ofspectropolarimetry and other observations of PPNs provides a powerfulway to constrain circumstellar morphology and dust parameters.
| 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.
| The general catalogue of trigonometric [stellar] paralaxes
Not Available
| Early type high-velocity stars in the solar neighborhood. IV - Four-color and H-beta photometry
Results are presented from photometric obaservations in the Stromgrenuvby four-color and H-beta systems of early-type high-velocity stars inthe solar neighborhood. Several types of photometrically peculiar starsare selected on the basis of their Stromgren indices and areprovisionally identified as peculiar A stars, field horizontal-branchstars, metal-poor stars near the Population II and old-disk turnoffs,metal-poor blue stragglers, or metallic-line A stars. Numerousphotometrically normal stars were also found.
| Early-type high-velocity stars in the solar neighborhood. I - List of candidates
Suspected nearby high-velocity stars of spectral types B and A areidentified by their proper motions, which are generally too small forthe stars to have been included in previous catalogs of high-velocitystars. The same selection process is then extended to spectral type Fstars, in order to both provide a companion sample and investigatewhether the hypothetical high-velocity, metal-rich population continuesto later spectral types. Of the presented list of 371 stars withconfirmed proper motions, 168 are of A and B spectral types. Photometricand spectroscopic observations of these stars are required to eliminatethose with misclassified spectra and convert proper motions into spacevelocities. The identification of type of stars is important forunderstanding apparent exceptions to the correlation between stellarages, metal abundances, and kinematic properties.
| Trigonometric parallaxes of 36 stars determined by photography with the MC Cormick 26-inch refractor.
Not Available
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Zurafa |
| Sað Açýklýk: | 04h59m04.33s |
| Yükselim: | +56°35'48.6" |
| Görünürdeki Parlaklýk: | 8.84 |
| Uzaklýk: | 147.275 parsek |
| özdevim Sað Açýklýk: | 65.5 |
| özdevim Yükselim: | -67.9 |
| B-T magnitude: | 9.208 |
| V-T magnitude: | 8.871 |
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