Using ultraviolet photometry from the Ultraviolet Imaging Telescope (UIT) combined with photometry and spectroscopy from three ground-based optical data sets we have analyzed the stellar content of OB associations and field areas in and around the regions N79, N81, N83, and N94 in the Large Magellanic Cloud. In particular, we compare data for the OB association Lucke-Hodge 2 (LH 2) to determine how strongly the initial mass function (IMF) may depend on different photometric reductions and calibrations.
Photometric observations of LQ Hya (HD 82558) obtained in 1995-2001 with the Phoenix 10 robotic telescope (Arizona) in the UBV bands with HD 82447 as the comparison star.
We present photoelectric UBV photometry for some 2600 metal-poor dwarf and giant candidates selected from the HK objective-prism/interference-filter survey of Beers and colleagues. These data provide the basis for our ultraviolet-excess selection of objects having [Fe/H]{<~}-2.0 for a spectroscopic investigation in which we have obtained ~1-2{AA} resolution spectra of some 1000 objects. The present material may also prove useful for investigations of the metal-poor dwarfs and giants more metal-rich than [Fe/H]=-2.0, as well as the misclassified subdwarf O and B stars, white dwarfs, blue metal-poor stars, and field horizontal-branch stars which appear in the catalog.
We present results of an extensive photometric monitoring campaign of the peculiar emission star MWC 560 that covers the range 1990-1995. The time interval corresponds to the length of the proposed orbital period of this highly peculiar binary, which attracted considerable interest in January-April 1990, when absorption components, shifted by -6000km/s from corresponding emission lines, were observed. Here we present photometric data secured during: 113 nights of conventional UBV photoelectric photometry, 45 nights of high speed UBV photoelectric photometry to study the flickering activity, and 682 visual photometric estimates. MWC 560 has experienced a decrease in magnitude since the bright (V=9.2mag) phase in 1990. After the minimum reached in May 1994 (V=10.7mag), the star is currently increasing slowly in brightness. The decrease has been accompanied in all bands by large fluctuations superimposed on the mean trend. The B-V colour has shown a steady increase by 0.0.33mag/yr. U-B has remained stable at -0.07mag since late 1990. In all the observing nights devoted to high speed photometry we observed flickering activity in MWC 560. The data show that the flickering amplitude {DELTA}U increases with the decrease of the U magnitude. Quasi-periodic variations have always been detected. A period of ~70min has been observed in ~13 nights which is close to the ~60min quasi-period reported by Michalitsianos et al. (1993). However, no coherent variability is traceable throughout the whole set of flickering data.
UBV and DDO photoelectric photometry in the field of the open cluster NGC 2323 is presented. The analysis yields 109 probable members; one of them being a red giant, and 3 possible members. The basic cluster parameters are derived. NGC 2323 appears not to be physically connected to the CMa OB1 association.
Photoelectric UBV values, derived from observations made at the Boyden and ESO observatories, are presented for 358 early-type stars in the Vela section of the southern Milky Way. Remarks, accurate positions and notes have been added in July 2016 at CDS (Francois Ochsenbein)
UBV photometry of OB associations in LMC superbubbles
Short Name:
J/ApJS/104/71
Date:
21 Oct 2021
Publisher:
CDS
Description:
This work presents UBV photometry of the stellar populations associated with seven superbubble nebulae and five classical H II regions in the Large Magellanic Cloud. Although the nebular morphology of the superbubbles appears to be substantially evolved compared to the classical nebulae, the color-magnitude diagrams do not reveal any noticeable correlation between the resident stellar population and nebular morphology. The photometry presented here will be used in a forthcoming paper to examine further the stellar content and dynamics of these superbubbles.
An analysis of photometric observations of the Be star OT Gem (HD 58050, HR 2817, 2000 position: 07 24 27.64 +15 31 02.0) is presented. A positive correlation between the light and colour variations and the emission strength was found.
We describe photometric and spectroscopic observations of the major outburst that AG Dra underwent between 2006 and 2008. The outburst peaked at U=8.4, B=9.0, V=8.7 around 2006 September 6, making it the brightest U-band event since the 1994 outburst. It was of the cold type, according to the classification of AG Dra outbursts introduced by Gonzalez-Riestra et al. (2006JAVSO..35..172G ). A second, fainter maximum (this time of the hot type) followed 400 days after the primary one, peaking at U=9.1, B=9.7, V=9.0 on 2007 October 7. The outburst phase ended about 600 days after the primary maximum. High resolution spectra obtained during early decline from primary maximum showed emission lines of Mg II, Si II, Ti II, and Fe II in addition to the usual lines of H, He I, and He II.
A detailed analysis of a very rich collection of spectroscopic and photometric observations of the bright Be star {phi} Per (HR 496, or HD 10516, 2000 position: 01 43 39.4 +50 41 20) is presented. Earlier reports that {phi} Per is a double-lined spectroscopic binary consisting of two emission-line objects are confirmed.
