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GPM - compiled catalogue of absolute proper motions of stars in selected areas of sky with galaxies.
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| GPM1 - a catalog of absolute proper motions of stars with respect to galaxies
The description of the first version of the General Compiled Catalogueof Absolute Proper Motions (GPM1) for a sample of HIPPARCOS stars,derived with respect to galaxies within the plan called Catalogue ofFaint Stars (KSZ, Deutch 1952), is presented. The principal aim of theGPM1 construction was to provide absolute proper motions of stars todetermine the rotation of the HIPPARCOS system. The GPM1 cataloguecontains 977 HIPPARCOS Input Catalogue stars with V magnitudes $5^m -11^m in 180 fields north of -25 degrees of declination. The accuracy ofthe proper motions is 8 mas/yr (milliarcseconds per year). Comparison ofproper motions of GPM1 with those of the PPM and ACRS was performed andanalyzed with respect to systematic errors caused by spurious rotationof the FK5 system. The standard errors show that the rotation may bedetermined with an accuracy better than 1 mas/yr. Catalog is onlyavailable in electronic form at the CDS via anonymous ftpcdsarc.u-strasbg.fr or ftp 130.79.128.5.
| Near-infrared line and continuum imaging of the nuclear starburst region of NGC 1808.
We present high spatial resolution (~1.0") imaging of Br?, H_2_1-0 S(1) 2.121?m and [Fe II] 1.64?m line emission and broad-bandJ, H and K continuum emission of the nuclear (20"=1.6kpc diameter)region of the starburst galaxy NGC 1808. These data, combined with a3.6cm radio continuum map, are used to study the morphology andextinction of the starburst region, the nature of the stellar populationand star formation, and the possibility of hidden Seyfert activity inNGC 1808. The broad-band continuum emission is smoothly distributedthroughout the circumnuclear region and peaks strongly on the nucleus.There is no strong morphological change with wavelength. Most of thecontinuum emission is probably produced by the evolved bulge stellarpopulation, and not by hot dust, red giants or red supergiants, as inmost other starburst galaxies. The line emission is dominated by thenucleus, but is extended along the major axis of the galaxy by ~18"(~1.4kpc) for all emission lines. The circumnuclear emission arises fromseveral distinct regions, forming a ring-like structure. Both Br?and [Fe II] are well correlated with the radio emission. There are,however, differences in the detailed morphology, that differentiatebetween hot spots dominated by supernova remnants and HII regions. TheH_2_ emission is slightly better spatially correlated with Br?than with [Fe II] emission but no firm conclusion about the excitationmechanism of the H_2_ is warranted. The Br? emission effectivelyisolates the star forming activity, whereas radio and [Fe II] emissionis affected by individual supernova explosions, and the optical H?emission peaks are only seen in directions of low extinction. Fromcomparison of Br? and H? fluxes we derive extinctionsbetween A_V_ of 3 and 5 towards the hot spots. From analysis of theextinction-corrected line and continuum emission luminosities using anevolutionary starburst model, we derive for each hot spot star formingrate 0.1-0.6Msun_/yr, and supernova rate 0.4-11x10^-3^yr^-1^.We estimate the age of the current burst to be between 8 and 17Myr inthe circumnuclear region, and ~40Myr in the nucleus. The circumnuclearstarburst hot spots lie in the area of HII regions and starburstgalaxies in the [Fe II]/Br? vs. H_2_/Br? diagram, whereasthe nucleus has line ratios similar to Seyfert nuclei. Themultiwavelength evidence for and against hidden Seyfert activity in NGC1808, and implications for the evolution of starburst galaxies arediscussed.
| Near-infrared photometry of stars
Results are presented of infrared photometric observations performed oncomparison stars during a monitoring of long-period variables. Theseobservations, spread over a lapse of about 5 years, are used to derivethe J, H, and K magnitudes of 54 stars in the photometric systemdescribed by Koornneef (1983). The 1950.0 coordinates, spectral types,visual magnitudes, average magnitudes, and the number of observationsare given for each object.
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Гидра |
| Прямое восхождение: | 09h40m38.08s |
| Склонение: | -21°34'53.9" |
| Видимая звёздная величина: | 7.735 |
| Расстояние: | 168.35 парсек |
| Собственное движение RA: | -68.6 |
| Собственное движение Dec: | 8.1 |
| B-T magnitude: | 8.98 |
| V-T magnitude: | 7.838 |
Каталоги и обозначения:
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