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.
This catalogue groups broad-band CCD photometry made in 8 regions of the Magellanic Clouds which were used for the study of stellar populations in the Magellanic Clouds. The photometry yielded 293693 BV entries with 136155 having additional U information, published or to be published in 4 different papers.
Spectra, position, magnitudes and colors are presented for 485 faint (B_J_<20.5) emission line objects selected with the ultraviolet-excess (UVX) criterion on a area of 24.6 sq. deg. in the South Galactic Pole. The objects were selected from the analysis of pixel-to-pixel stacking of COSMOS scans of UKST U_J_ and R plates. The candidates were observed with the Meudon-ESO Fiber Optics System (MEFOS) at the ESO 3.6m telescope. 429 type 1 AGNs have been identified (373 in the redshift range 0.3<z<=2.2). This sample has allowed the measure of a difference on the QSO clustering evolution in comparison with that found for galaxies (La Franca et al., 1998ApJ...497..529L). The region is part of the ESO Imaging Survey (EIS) and of the 2dF QSO redshift survey.
Photoelectric, CCD, and photographic photometry is presented for a sample of 163 stars in the field of the short-period Cepheid SU Cyg for the purpose of searching for a putative cluster that might be associated with the Cepheid. Although the variable is situated in a clump of stars that has the appearance of a sparse cluster, the photometric evidence indicates that they are not a physical group. About two dozen B and A-type stars randomly distributed in the field lie at a common distance of 1086+/-60pc (V_0_-M_V_= 10.18+/-0.12 for R=2.94+/-0.38), but they are likely to represent at best a segment of the Vul OB4 association, which overlaps the region. SU Cyg is unlikely to be a member of that group. The close optical companion to SU Cyg, an A2 V star with a radial velocity (<VR>=-23.6+/-7.1km/s) close to the systemic velocity of the Cepheid, is a spectroscopic binary that might be physically related to the variable. Its primary importance is for helping to establish a space reddening of E_(B-V_)=0.15+/-0.01 for SU Cyg. Despite the lack of related cluster stars to SU Cyg, its two unresolved companions can be used to place restrictions on the likely luminosity of the Cepheid. The resulting value of <M_V_><=-3.02+/-0.23 relative to its companions agrees closely with a value of <MV>(PLC)=-3.03+/-0.07 obtained from the Cepheid PLC relation.
We present UBV photometry of the highly reddened and poorly studied open cluster Berkeley 55 (= C 2115+515), revealing an important population of B-type stars and several evolved stars of high luminosity. Intermediate-resolution far-red spectra of several candidate members confirm the presence of one F-type supergiant and six late supergiants or bright giants. The brightest blue stars are mid-B giants. Spectroscopic and photometric analyses indicate an age 50+/-10Myr. The cluster is located at a distance d~4kpc, consistent with other tracers of the Perseus Arm in this direction. Berkeley 55 is thus a moderately young open cluster with a sizable population of candidate red (super)giant members, which can provide valuable information about the evolution of intermediate-mass stars.
