Related papers: The 2003 Shell Event in eta Carinae
We present a 4 year light curve of a cataclysmic variable in M22, based on an analysis of accumulated data from the MOA microlensing survey. The position of the star coincides with that of a transient event observed by HST in 1999,…
$\eta$ Carinae is a colliding wind binary hosting two of the most massive stars and featuring the strongest wind collision mechanical luminosity. The wind collision region of this system is detected in X-rays and $\gamma$-rays and offers a…
We report the results of multi-epoch observations of Sgr A* with VLBI Exploration of Radio Astrometry (VERA) at 43 GHz, carried out from 2004 to 2008. We detected a time variation of flux at 11 % level and intrinsic size at 19 %. In…
Context. The mass loss from massive stars is not understood well. Eta Car is a unique object for studying the massive stellar wind during the LBV phase. It is also an eccentric binary with a period of 5.54 yr. The nature of both stars is…
The evolved, massive highly eccentric binary system, eta Carinae, underwent a periastron passage in the summer of 2014. We obtained two coordinated X-ray observations with XMM-Newton and NuSTAR during the elevated X-ray flux state and just…
In October 2024, the object BL Lacertae experienced the brightest flaring event in gamma-ray ($>$100 MeV) with a historically bright $\gamma$-ray flux of $\sim$2.59 $\times 10^{-5}$ erg cm$^{-2}$ s$^{-1}$ with a detection of a 175.7 GeV…
The HST archive contains a large collection of images of eta Carinae, and this paper analyzes those most suitable for measuring its expanding Homunculus Nebula. Multiple intensity tracings through the Homunculus reveal the fractional…
We report an exceptional mid-infrared flare in the Seyfert 1.8 NGC 3786. In the multi-epoch data from the Wide-field Infrared Survey Explorer, the nuclear mid-infrared brightness of NGC 3786 appears to vary substantially up to $0.5-0.8$ mag…
Blazars show optical and $\gamma$-ray flux variations that are generally correlated, although there are exceptions. Here we present anomalous behaviour seen in the blazar 3C 454.3 based on an analysis of quasi-simultaneous data at optical,…
We present optical spectra of the ionized `Outer Ejecta' of Eta Carinae that reveal differences in chemical composition at various positions. In particular, young condensations just outside the dusty Homunculus Nebula show strong nitrogen…
The central star V4334 Sgr (Sakurai's Nova) of the planetary nebula PN G010.4+04.4 underwent in 1995-1996 the rare event of a very late helium flash. It is only one of two such events during the era of modern astronomy (the second event was…
We present 19 binary lens candidates from OGLE-III Early Warning System database for the season of 2004. We have also found five events interpreted as single mass lensing of double sources. The candidates have been selected by visual light…
This paper discusses a model where a violent periastron collision of stars in an eccentric binary system induces an eruption or explosion seen as a brief transient source, attributed to LBVs, SN impostors, or other transients. The key…
Within the 'Medicina/Effelsberg H2O maser monitoring program' we observed U Her and RR Aql at 22-GHz for about two decades between 1990 and 2011, with a gap between 1997 and 2000 in the case of RR Aql. In addition, maps were obtained in the…
We present an analysis of the visible through near infrared spectrum of Eta Carinae and its ejecta obtained during the "Eta Carinae Campaign with the UVES at the ESO VLT". This is a part of larger effort to present a complete Eta Carinae…
After the Observing Campaign of Eta Carinae carried out during 2003, we have continued the CCD observations using the 0.8 m Reflector telescope at La Plata Observatory, in the BVRI bands. Here, we present the results obtained since November…
The extremely luminous and unstable star Eta Carinae is surrounded by ejecta formed during the star's giant eruption around 1843. The optical nebula consists of an inner region, the bipolar Homunculus and the outer ejecta. The X-ray…
Observations of the type II SN 1996L reveal the presence of a slowly expanding (V~700$ km/s) shell at ~ 10^(16) cm from the exploding star. Narrow emission features are visible in the early spectra superposed on the normal SN spectrum.…
Using the SIT instrument aboard STEREO we have examined the abundance of the 3He during the ascending phase of solar cycle 24 from January 2010 through December 2012. We report on several cases when 3He-rich solar energetic particle events…
I discuss some observational properties of aspherical nebulae around massive stars, and conclusions inferred for how they may have formed. Whether or not these ideas are applicable to the shaping of planetary nebulae is uncertain, but the…