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CCD measurements of visual double stars made with the 74 cm and 50 cm refractors of the Nice Observatory (2nd series)
We present 619 measurements of 606 visual double stars made by CCDimaging from 1996 to 1999 with the 74 cm and 50 cm refractors of theNice observatory. Angular separation, position angle and magnitudedifference are given. Magnitude differences estimated from CCD imagesare compared with magnitude differences given in the Hipparcos catalog.The residuals in angular separation and position angle are computed forbinaries with known orbit. Table 2 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/378/954
| Electron temperatures in planetary nebulae
Published observational data on the intensities of the forbidden linesof O III and/or N II in 107 planetary nebulae (PN) are used along withthe atomic parameters compiled by Mendoza (1983) to determine the PNelectron temperatures (Te). The ratio of Te from N II to Te from O IIIis found to vary smoothly and strongly as a function of overall nebularexcitation.
| Statistical survey of planetary nebulae - Distances, masses, and distribution in the galaxy
A new empirical scale of distances to planetary nebulae (PNs) ispresented based on the interdependence between the PN diameter and thevalue of the surface brightness in the radio range. The dependence ofthe mean electron density in PNs on the diameter is determined, and themasses of the ionized matter in PNs are estimated. The variation of theproperties of PNs as a function of the type of stellar population towhich they belong is investigated, and the frequency of PN formation inthe Galaxy is evaluated and compared with that of white dwarf formation.Finally, the dependence of the PN expansion velocity on linear size isdefined.
| The dynamics, evolution and formation rate of planetary nebulae
The relation between nebular expansion velocity and radius is reassessedusing the revised distance scale of Pottasch (1980) and others. Contraryto previous investigations, velocity is found to increase only graduallyand nonlinearly with nebular radius for the majority of nebulae. Thisresult is used to determine a nebular formation rate of 0.0044 + or -0.0015/cu kpc/yr, similar to that for white dwarfs. The revised nebularexpansion timescale implies central star masses of about 0.75 solar masswith an overall range of 0.6-1.0 solar mass. This suggests correspondingmasses of 0.7-1.5 solar mass for the central star progenitors. A clearrelationship is found between central star spectral type and mass, withO and WC stars located predominantly in the mass range below 0.7 solarmass, and WR+O stars representing the range above 0.8 solar mass. Theeffect of stellar wind on nebular dynamics is briefly considered.
| Micrometer observations of double stars.8.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJS...29..315H&db_key=AST
| Star-streaming from the proper motion of the A-type stars of the Boss General Catalogue
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1954MNRAS.114..593T&db_key=AST
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | אנדרומדה |
| התרוממות ימנית: | 00h07m35.18s |
| סירוב: | +31°40'08.4" |
| גודל גלוי: | 6.88 |
| מרחק: | 165.289 פארסק |
| תנועה נכונה: | 8.8 |
| תנועה נכונה: | -19.6 |
| B-T magnitude: | 8.325 |
| V-T magnitude: | 7 |
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