The symbiotic binary system RX Puppis: a possible recurrent nova with a Mira companion

We present an analysis of photometric and spectroscopic observations of the symbiotic binary system RX Pup with the aims of developing a reliable binary for the system and identifying mechanisms responsible for its spectacular activity. The binary is composed of a long-perod Mira variable surrounded by a thick dust shell and a hot white dwarf companion. The hot component produces practically all activity observed in the UV, optical and radio range, while variable obscuration of the Mira by circumstellar dust is responsible for long-term changes in the near-IR magnitudes. The observations show RX Pup underwent a nova-like eruption during the last three decades. The hot component contracted in radius at roughly constant luminosity from 1975 to 1986, and was the source of a strong stellar wind which prevented it from accreting material lost in the Mira wind. Around 1988/9 the hot component turned over in the HR diagram and by 1991 its luminosity had faded by a factor of about 30 with respect to the maximum plateau value and the hot wind had practically ceased. By 1995 the nova remnant started to accrete material from the Mira wind, as indicated by a general increase in intensity of the optical continuum and HI emission. The quiescent spectrum resembles the quiescent spectra of symbiotic recurrent novae, and its intensity indicates the hot component must accrete as much as about 1 per cent of the Mira wind, which is more or less the amount predicted by Bondi-Hoyle theory. The earliest observational records from the 1890s suggest that another nova-like eruption of RX Pup occurred around 1894.Comment: 23 pages, 12 figues, MNRAS - accepte

The effect of dust obscuration in RR Tel on optical and IR long-term photometry and Fe II emission lines

Infrared and optical photometric and spectroscopic observations of the symbiotic nova RR Tel are used to study the effects and properties of dust in symbiotic binaries containing a cool Mira component, as well as showing "obscuration events" of increased absorption, which are typical for such Miras. A set of photometric observations of the symbiotic nova RR Tel in different wavelength bands - visual from 1949 to 2002 and near-infrared (JHKL) from 1975 to 2002 - are presented. The variability due to the normal Mira pulsation was removed from the JHKL data, which were then compared with the AAVSO visual light curve. The changes of the Fe II emission line fluxes during the 1996-2000 obscuration episode were studied in the optical spectra taken with the Anglo-Australian telescope. We discuss the three periods during which the Mira component was heavily obscured by dust as observed in the different wavelength bands. A change in the correlations of J with other infrared magnitudes was observed with the colour becoming redder after JD2446000. Generally, J-K was comparable, while K-L was larger than typical values for single Miras. A distance estimate of 2.5 kpc, based on the IR data, is given. A larger flux decrease for the permitted than for the forbidden Fe II lines, during the obscuration episode studied, has been found. There is no evidence for other correlations with line properties, in particular with wavelength, which suggests obscuration due to separate optically thick clouds in the outer layers.Comment: 19 pages, 11 figures, 3 table

UBV(RI)C JHK observations of Hipparcos-selected nearby stars

We present homogeneous, standardized UBV(RI)C photometry for over 700 nearby stars selected on the basis of Hipparcos parallaxes. Additionally, we list JHK photometry for about half of these stars, as well as L photometry for 86 of the brightest. A number of stars with peculiar colours or anomalous locations in various colour–magnitude diagrams are discussed.Web of Scienc

Further observations of Hipparcos red stars and standards for UBV(RI)C photometry

We present homogeneous and standardized UBV(RI)C JHK photometry for over 100 M stars selected from an earlier paper on the basis of apparent photometric constancy. L photometry has been obtained for stars brighter than about L = 6. Most of the stars have a substantial number of UBV(RI)C observations and, it is hoped, will prove useful as red supplementary standards. Additionally,we list JHK photometry for nearly 300 Hipparcos red stars not selected as standards, as well as L photometry for the brightest stars.Web of Scienc

Properties of galactic B[e] supergiants. IV. Hen3-298 and Hen3-303

We present the results of optical and near-IR spectroscopic and near-IR photometric observations of the emission-line stars Hen3-298 and Hen3-303. Strong emission in the H-alpha line is found in both objects. The presence of Fe II and [O I] emission lines in the spectrum of Hen3-298 indicates that it is a B[e] star. The double-peaked CO line profiles, found in the infrared spectrum of Hen3-298, along with the optical line profiles suggest that the star is surrounded by a rotating circumstellar disk. Both objects also show infrared excesses, similar to those of B[e] stars. The radial velocities of the absorption and emission lines as well as a high reddening level suggest that the objects are located in the Norma spiral arm at a distance of 3-4.5 kpc. We estimated a luminosity of log (L/L_sun) ~ 5.1 and a spectral type of no earlier than B3 for Hen3-298. Hen3-303 seems to be a less luminous B-type object (log (L/L_sun) ~ 4.3), located in the same spiral arm.Comment: 8 pages, 5 figures, accepted by Astronomy and Astrophysic

The mysterious eruption of V838 Mon

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 several s-elements, with wide P-Cyg profiles and a moderate and retracing emission in the Balmer lines. A light-echo discovered expanding around the object helped to constrain the distance (d=790+/-30 pc), providing M_V=+4.45 in quiescence and M_V=-4.35 at optical maximum (somewhat dependent on the still uncertain E(B-V)=0.5 reddening). The general outburst trend is toward lower temperatures and larger luminosities, and continuing so at the time of writing. The object properties conflict with a classification within already existing categories: the progenitor was not on a post-AGB track and thus the similarities with the born-again AGB stars FG Sge, V605 Aql and Sakurai's object are limited to the cool giant spectrum at maximum; the cool spectrum, the moderate wind velocity (500 km/sec and progressively reducing) and the monotonic decreasing of the low ionization condition argues against a classical nova scenario. The closest similarity is with a star that erupted into an M-type supergiant discovered in M31 by Rich et al. (1989), that became however much brighter by peaking at M_V=-9.95, and with V4332 Sgr that too erupted into an M-type giant (Martini et al. 1999) and that attained a lower luminosity, closer to that of V838 Mon. M31-RedVar, V4332 Sgr and V838 Mon could be manifestations of the same and new class of astronomical objects.Comment: A&A, in pres