Light variations of massive stars (α Cygni variables). XIV. The hypergiant WRA 977=BP CRU and the luminous blue variable (LBV) HDE 269582=HV 5495 in the LMC.
We present and discuss new multi-colour photometry of the massive X-raybinary and hypergiant WRA 977=BP Cru and the luminous blue variable(LBV) HDE 269582=HV 5495 in the LMC. The light variations of WRA 977 aretypical for a normal α Cyg variable and show an averagequasi-period of 11.90d over a time interval of 17yr. The distance couldbe as large as 7.7+/-2.3kpc. The light variations of HDE 298582=HV5495=MWC 112, showing a timescale of 1-2yr, have an amplitude of0.3-0.5mag. This points to an LBV near minimum light. The colourvariation is also typical for an LBV.
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A suspected K3V variable
Not Available
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Longterm Photometry of Variables at ESO - Part Two - the Second Data Catalogue 1986-1990
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..102...79S&db_key=AST
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Long-term photometry of variables at ESO. I - The first data catalogue (1982-1986)
This paper presents the catalog of photometric data in the Stromgrensystem obtained during the first four years (October 1982 - September1986) of the Long-Term Photometry of Variables (LTPV) program at ESO.The data are available in computer-readable form.
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The distance and structure of the Coalsack. I - Photometric data
The results of UBV and H-beta photometry for 284 stars of spectral typesB to F located in the area of the dark cloud Coalsack are presented.Most of the present stars are brighter than 10.0 mag and are classifiedin the MK system of Houk and Cowley (1975). For each star, the bestvalues for the extinction and distance modulus are provided, withtypical estimated errors of + or - 0.08 mag for the extinction and + or- 0.32 mag for the distance modulus. Possible misclassifications andspectral peculiarities are noted for several of the stars.
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The Southern Coalsack - Extinction and distance
H-beta and uvby photometric observations are reported for 236 stars oftypes B, A, and F in the region of the Southern Coalsack. Data obtainedwith the 50-cm Stromgren Automatic Telescope at ESO are presented inextensive tables, graphs, and maps and characterized in detail. Threedistinct structures are identified: (1) a nearby region (d less than 200pc) dominated by stars in front of the Coalsack, with evidence of a verydiffuse feature; (2) an intermediate region (d = 200-1100 pc) with starsreddened by Coalsack dust and/or the ISM behind it; and (3) a distantregion (d = 1.1-3.0 kpc) in which the reddening of 22 early B starsimplies a color-excess lower limit of E(b-y) = 0.230 mag, consistentwith a 10,000-solar-mass cloud at d = 1.2 kpc. The average upper-limitdistance to the main Coalsack components is estimated as 180 + or - 26pc, with some material possibly as near as 120 pc.
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Stromgren and H-beta photometry of stars earlier than G0 in the Southern Coalsack direction
Four-color and H-beta photometry have been obtained for 236 starsearlier than G0 in order to study the color excess distribution in theSouthern Coalsack direction. The beta histogram of the stars reveals arelative absence of stars in the range of A4 to A9. The (b-y)distribution for B-type stars suggests the existence of three differenttypes of stars located at different distances.
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Instrumental effects and the Stroemgren photometric system
The extent to which the use of different photometers can affect resultson stellar color indices was investigated by simultaneously observing asample of widely different stars with several uvby photometric systemsavailable at the ESO, La Silla, Chile. In one instance, the ESO 50-cmtelescope and the four-channel photometer at the Danish 50-cm telescopewere used simultaneously. The reductions were performed separately oneach data set, using a linear color transformation procedure. Theresults agree with theoretical investigations which showed thatsubstantial errors can arise from the nonconformity of passbands. It isemphasized that it is necessary to use separate color transformationsfor various stellar types and classes and for different interstellarreddenings.
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INHABITED SKY
