Related papers: A lambda 3mm and 1mm line survey toward the yellow…
We have used the sub-millimeter array to image the molecular envelope around IRC+10420. Our observations reveal a large and clumpy expanding envelope around the star. The molecular envelope shows a clear asymmetry in $^{12}$CO J=2--1…
The yellow hypergiant stars (YHGs) are extremely luminous and massive objects whose general properties are poorly known. Only two of this kind of star show massive circumstellar envelopes, IRC+10420 and AFGL2343. We aim to study the…
The fate of a massive star during the latest stages of its evolution is highly dependent on its mass-loss history and geometry, with the yellow hypergiants being key objects to study those phases of evolution. We present near-IR…
Among evolved massive stars likely in transition to the Wolf-Rayet phase, IRC +10420 is probably one of the most enigmatic. It belongs to the category of yellow hypergiants and it is characterized by quite high mass loss episodes. Even…
The circumstellar envelope of the hypergiant star IRC+10420 has been traced as far out in SiO J=2-1 as in CO J = 1-0 and CO J = 2-1, in dramatic contrast with the centrally condensed (thermal) SiO- but extended CO-emitting envelopes of…
IRC +10420 is one of the few known massive stars in rapid transition from the Red Supergiant phase to the Wolf-Rayet or Luminous Blue Variable phase. The star has an ionised wind and using the Br gamma hydrogen recombination emission we…
IRC +10420 is one of the extreme hypergiant stars that define the empirical upper luminosity boundary in the HR diagram. During their post--RSG evolution, these massive stars enter a temperature range (6000-9000 K) of increased dynamical…
Yellow hypergiants represent a short-lived evolutionary episode experienced by massive stars as they transit to and from a red supergiant phase. As such, their properties provide a critical test of stellar evolutionary theory. The galactic…
IRC+10216 is the brightest infrared source in the northern sky, known for its rich chemical composition. It is often used as a standard reference for studying the circumstellar envelope (CSE) of carbon-rich stars. While pioneering 3\,mm…
The hypergiant IRC+10420 is a unique object for the study of stellar evolution since it is the only object that is believed to be witnessed in its rapid transition from the red supergiant stage to the Wolf-Rayet phase. Its effective…
IRC +10216 is the prototypical carbon star exhibiting an extended molecular circumstellar envelope. Its spectral properties are therefore the template for an entire class of objects. The main goal is to systematically study the $\lambda$…
Despite their large impact on stellar and galactic evolution, the properties of outflows from red supergiants are not well characterised. We used the Onsala 20m telescope to perform a spectral survey at 3mm and 4mm (68 - 116 GHz) of the red…
We report on the detection of vinyl cyanide (CH2CHCN), cyanomethyl radical (CH2CN), methylacetylene (CH3CCH) and thioformaldehyde (H2CS) in the C-rich star IRC +10216. These species, which are all known to exist in dark clouds, are detected…
We investigate the molecular gas properties of a sample of 23 galaxies in order to find and test chemical signatures of galaxy evolution and to compare them to IR evolutionary tracers. Observation at 3 mm wavelengths were obtained with the…
We present the results of our spectral line surveys in the 2 mm and 1.3 mm windows toward the carbon rich envelope of IRC +10216. Totally 377 lines are detected, among which 360 lines are assigned to 57 known molecules (including 29 rare…
We present low spectral resolution molecular interferometric observations at 1.2 mm obtained with the Combined Array for Research in Millimetre-wave Astronomy (CARMA) towards the C-rich AGB star IRC+10216. We have mapped the emission of…
Red supergiant stars (RSGs) and yellow hypergiant stars (YHGs) are believed to be the high-mass counterparts of stars in the AGB and early post-AGB phases. We study the mass-loss in the post main-sequence evolution of massive stars, through…
We present an unbiased $\lambda$ 3 mm spectral line survey (between 84.5 and 115.8 GHz), conducted by the Purple Mountain Observatory 13.7 meter radio telescope, together with updated modeling results, towards the carbon-rich Asymptotic…
We attempt to characterise the chemical properties of a sample of massive clumps of IRDCs through multi-molecular line observations. We also search for possible evolutionary trends among the derived chemical parameters. The clumps are…
Submillimeter Array 1.3mm line and continuum observations toward the young massive star-forming region IRAS18182-1433 are presented. The data are complemented with short-spacing CO(2-1) observations and SiO(1-0) data from the VLA. Multiple…