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AGB nucleosynthesis in the Large Magellanic Cloud. Detailed abundance analysis of the RV Tauri star MACHO?47.2496.8
Context: Abundance analysis of post-AGB objects as probes of AGBnucleosynthesis. Aims: A detailed photospheric abundance study isperformed on the carbon-rich post-AGB candidate MACHO 47.2496.8 in theLMC. Methods: High-resolution, high signal-to-noise ESO VLT-UVESspectra of MACHO 47.2496.8 are analysed by performing detailed spectrumsynthesis modelling using state-of-the-art carbon-rich MARCS atmospheremodels. Results: The spectrum of MACHO 47.2496.8 is not onlydominated by bands of carbon bearing molecules, but also by lines ofatomic transitions of s-process elements. The metallicity of [Fe/H] =-1.4 is surprisingly low for a field LMC star. The C/O ratio, howeverdifficult to quantify, is greater than 2, and the s-process enrichmentis large: the light s-process elements are enhanced by 1.2 dex comparedto iron ([ls/Fe] = +1.2), while for the heavy s-process elements an evenstronger enrichment is measured: [hs/Fe] = +2.1. The lead abundance iscomparable to the [hs/Fe]. With its low intrinsic metallicity and itsluminosity at the low end of the carbon star luminosity function, thestar represents likely the final stage of a low initial mass star. Conclusions: .The LMC RV Tauri star MACHO 47.2496.8 is highly carbonand s-process enriched, and is most probable a genuine post-C(N-type)AGB star. This is the first detailed abundance analysis of anextragalactic post-AGB star to date.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
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| An Atlas of Spectrophotometric Landolt Standard Stars
We present CCD observations of 102 Landolt standard stars obtained withthe Ritchey-Chrétien spectrograph on the Cerro TololoInter-American Observatory 1.5 m telescope. Using stellar atmospheremodels, we have extended the flux points to our six spectrophotometricsecondary standards, in both the blue and the red, allowing us toproduce flux-calibrated spectra that span a wavelength range from 3050Å to 1.1 μm. Mean differences between UBVRI spectrophotometrycomputed using Bessell's standard passbands and Landolt's publishedphotometry were determined to be 1% or less. Observers in bothhemispheres will find these spectra useful for flux-calibrating spectra,and through the use of accurately constructed instrumental passbands,will be able to compute accurate corrections to bring instrumentalmagnitudes to any desired standard photometric system (S-corrections).In addition, by combining empirical and modeled spectra of the Sun,Sirius, and Vega, we calculate and compare synthetic photometry toobserved photometry taken from the literature for these three stars.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| The atmospheric extinction at Estacion Astronomica "Dr. Carlos Ulrrico Cesco".
Abstract image available at:http://adsabs.harvard.edu/abs/1993RMxAA..25...91G
| UBV(RI)c photometry of equatorial standard stars - A direct comparison between the northern and southern systems
UBV(RI)c photometry of 212 stars from Landolt's list of equatorialstandards is presented. The observations are tied to the system definedby Cousin's E-region standards. A comparison of the present results withLandolt's reveals reasonably good agreement for (V-R)c and (V-I)c, butmarked systematic differences for (B-V) and (U-B). The UBV systems ofCousins and Landolt are evidently not the same and both probably differfrom Johnson's original system.
| Selection of standard stars for photometric observations with the 91-cm reflector at Okayama
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| UBVRI photometric standard stars around the celestial equator
It is pointed out that accurate, internally consistent, and readilyaccessible standard star photometric sequences are necessary for thecalibration of the intensity and color data which astronomers obtain atthe telescope. The photometric results provided in connection with thepresent study represent the first part of an effort which is concernedwith the presentation of UBVRI photoelectric photometric standard starsin the magnitude range from 7 to 17 over as broad a range in color aspossible. All of the photometric observations were made with a 31034type photomultiplier used in a pulse counting mode. Some 15 to 25standard stars chosen from Cousins' lists (1973, 1976) in the E-regionswere observed with an 0.4-m telescope each night along with the programstars. UBVRI standard stars were observed periodically throughout thenight. Observations with a 0.9-m telescope were also conducted. TheUBVRI photoelectric observations take into account 223 stars.
| Spectral classifications for Landolt's celestial equatorial standard stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979AJ.....84..783D&db_key=AST
| Equatorial UBVRI photoelectric sequences
From 1335 BVRI observations of 189 stars in selected areas 92-115,Landolt's (1973) network of faint UBV standards has been extended to RI. Of these stars, 173 have four or more observations. The (U-B) valuesof Landolt are adopted, and a well-observed equatorial faint-starnetwork is presented on the Johnson UBVRI photometric system.
| Distances to eclipsing binaries. III - Masses, radii, and absolute magnitudes of 96 stars
Distances to, and absolute magnitudes of, 96 components of eclipsingbinaries with well-determined absolute dimensions have been computedusing V-R photometry. The calculations take into account interstellarreddening, which is estimated from existing UBV and uvby-betaphotometry, as well as photometric proximity effects. The resultingabsolute magnitudes, dimensions, and masses are compared with zero-agemain sequences predicted by theory. Theory is in good agreement with theobserved data for stars more massive than the sun if a composition (X,Y, Z) = (0.66 + or - 0.03, 0.303 + or - 0.03, 0.037 + or - 0.005) ischosen. The corresponding helium-to-hydrogen number ratio is 0.115 + or- 0.02, in agreement with previous estimates.
| Catalog of Indidual Radial Velocities, 0h-12h, Measured by Astronomers of the Mount Wilson Observatory
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...19..387A&db_key=AST
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Observation and Astrometry data
| Constellation: | Orion |
| Right ascension: | 04h51m40.77s |
| Declination: | -00°05'13.2" |
| Apparent magnitude: | 8.959 |
| Distance: | 1388.889 parsecs |
| Proper motion RA: | 6.1 |
| Proper motion Dec: | 1.8 |
| B-T magnitude: | 10.264 |
| V-T magnitude: | 9.067 |
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INHABITED SKY
