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Some classes of stars, including novae and supernovae, undergo explosive outbursts that eject stellar material into space. In 2002, the previously unknown variable star V838 Monocerotis brightened suddenly by a factor of approximately 10(4). Unlike a supernova or nova, it did not explosively eject its outer layers; rather, it simply expanded to become a(More)
  • P. Rodŕıguez-Gil, M. Santander-Garćıa, +13 authors M. M. Rubio-Dı́ez
  • 2010
We present time-resolved optical spectroscopy of V458 Vulpeculae (Nova Vul 2007 No. 1) spread over a period of 15 months starting 301 days after its discovery. Our data reveal radial velocity variations in the He ii λ5412 and He ii λ4686 emission lines. A period analysis of the radial velocity curves resulted in a period of 98.09647±0.00025 min(More)
V838 Mon is marking one of the most mysterious stellar outbursts on record. The spectral energy distribution of the progenitor resembles an under-luminous F main sequence star (at V =15.6 mag), that erupted into a cool supergiant following a complex and multi-maxima lightcurve (peaking at V =6.7 mag). The outburst spectrum show BaII, LiI and lines of(More)
We present observations proving the close binary nature of the central stars belonging to the planetary nebulae (PNe) NGC 6326 and NGC 6778. Photometric monitoring reveals irradiated lightcurves with orbital periods of 0.372 and 0.1534 days, respectively, constituting firm evidence that they passed through a common-envelope (CE) phase. Unlike most surveys(More)
Aims. Eleven new symbiotic stars have recently been discovered with IPHAS, the INT Hα survey of the Northern Galactic plane. The star IPHAS J190832.31+051226.6 was proposed as an additional candidate on the basis of the existing spectrum. Here, we investigate the nature of this source by means of additional observations. Methods. Photometric data, optical(More)
We introduce the log(Hα/[S ii]λλ6717+6731) vs. log(Hα/[N ii]λ6583) (S2N2) diagnostic diagram as metallicity and ionisation parameter indicator for H ii regions in external galaxies. The location of H ii regions in the S2N2 diagram was studied both empirically and theoretically. We found that, for a wide range of metallicities, the S2N2 diagram gives single(More)
The INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS) is a 1800 square degrees CCD survey of the northern Milky Way spanning the latitude range −5 o < b < +5 o and reaching down to r ′ ≃ 20 (10σ). It may increase the number of known northern emission line sources by an order of magnitude. Representative observations and an assessment of(More)
We obtained optical long-slit spectra of four planetary nebulae (PNe) with low-ionization pair of knots, namely He 1-1, IC 2149, KjPn 8 and NGC 7662. These data allow us to derive the physical parameters and excitation of the pairs of knots, and those of higher ionization inner components of the nebulae, separately. Our results are as follows. 1) The(More)
We report on the discovery of ETHOS 1 (PN G068.1+11.0), the first spectroscopically confirmed planetary nebula (PN) from a survey of the SuperCOSMOS Science Archive for high-latitude PNe. ETHOS 1 stands out as one of the few PNe to have both polar outflows (jets) travelling at 120 ± 10 km/s and a close binary central star. The lightcurve observed with the(More)
Aims. The determination of reliable distances to planetary nebulae (PNe) is a major difficulty in the study of this class of objects in the Galaxy. The availability of new photometric surveys such as IPHAS (the INT/WFC photometric H α survey of the northern Galactic plane) covering large portions of the sky provide an opportunity to apply the so-called(More)