We build an accurate database of 5200 HCN and HNC rotation-vibration energy levels, determined from existing laboratory data. 20~000 levels in the Harris et al. (2002) linelist are assigned approximate quantum numbers. These assignments, lab al incorporated to a new level list. A is presented, which frequencies computed using where available, ab initio otherwise. The then used compute model atmospheres synthetic spectra for carbon star WZ Cas. This results better fit spectrum Cas absorption...

We exploit the spectral archive of Sloan Digital Sky Survey (SDSS) Data Release 7 to select unusual quasar spectra. The selection method is based on a combination power self-organising maps and visual inspection huge number Self-organising were applied nearly 10^5 spectra classified as quasars by SDSS pipeline. Particular attention was paid minimise possible contamination rare peculiar stellar types. present catalogue 1005 with This large sample provides useful resource for both studying...

A line list of vibration-rotation transitions for 13C substituted HCN is presented. The constructed using known experimental levels where available, calculated and ab initio intensities originally the major isotopologue. Synthetic spectra are generated compared with observations cool carbon star WZ Cas. It suggested that high resolution recorded near 14 micron should be particularly sensitive to 12C ratio.

Aims.We report results of a quantitative colorimetric UBVRI analysis two flare events on the red dwarf EV Lac. The photometric data were obtained in September 2004, during multi-site synchronous monitoring from four observatories Ukraine, Russia, Greece, and Bulgaria. These observations confirmed presence small-scale high-frequency oscillations (HFO) initially detected by Rodonó (1974, A&A, 32, 337) recently reconfirmed authors. Here we discuss color characteristics flares HFO.

Context. We report the results from determination of stellar masses, carbon and oxygen abundances in atmospheres 107 stars CHEPS program. Our are drawn a population with significantly super-solar metallicity. At least 10 these known to host orbiting planets. Aims. In this work, we set out understand behavior abundance different spectral classes, metallicities V sin i , within metal-rich population. Methods. Masses were determined using data Gaia DR2 release. The by fitting absorption lines....

Lithium in the atmosphere of a F or G supergiant reflects initial Li abundance and internal history star. During evolution star from main sequence (MS) to phase, lithium may be destroyed by, for example, rotationally induced mixing MS stars strongly diluted by development supergiant's convective envelope. In order probe connection between atmospheric evolutionary predictions, we present non-local thermodynamic equilibrium analysis resonance doublet i at 6707.8 Å 55 Galactic supergiants...

A time series of high-resolution spectra was observed in the optical wavelength region for bright proto-planetary nebula IRAS22272+5435 (HD235858), along with a simultaneous monitoring its radial velocity and $BVR_C$ magnitudes. The object is known to vary light, color, due pulsation period 132 days. light color variations are accompanied by significant changes spectral features, most which identified as lines carbon-bearing molecules. According observations, $C_2$ Swan system CN Red...

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Context. We report results from lithium abundance determinations using high resolution spectral analysis of the 107 metal-rich stars Calan-Hertfordshire Extrasolar Planet Search programme. Aims. aim to set out understand distribution population taken this survey. Methods. The taking account non-local thermodynamical equilibrium effects was determined fits Li I 6708 Å resonance doublet profiles in observed spectra. Results. find that a) fast rotators tend have higher abundances; b) log N (Li)...

The aim of the project is to define a metallicity/gravity/temperature scale vs spectral types for metal-poor M dwarfs. We obtained intermediate-resolution ultraviolet (R~3300), optical (R~5400), and near-infrared (R~3900) spectra 43 subdwarfs (sdM), extreme (esdM), ultra-subdwarfs (usdM) with X-shooter spectrograph on European Southern Observatory Very Large Telescope. compared our atlas latest BT-Settl synthetic energy distribution over wide range metallicities, gravities, effective...

Abstract Thulium abundance is unknown in the atmospheres of low and medium-mass evolved stars. The reason weakness lines crowded spectra. We examined spectra two late-type stars a broad wavelength region to search for thulium lines. was estimated barium star HD 204075 post-asymptotic giant branch 235858 first time, <?CDATA $\mathrm{log}\,\epsilon (\mathrm{Tm})\simeq 0.1$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mspace...

We present near infrared spectroscopy of the recurrent nova RS Oph obtained on several occasions after its latest outburst in 2006 February. The 1-5 mircon spectra are dominated by red giant, but H I, He and coronal lines during eruption all our observations. From fits computed spectral energy distributions to observed fluxes we find T_eff=4200+/-200,K for giant. first overtone CO bands at 2.3 micron, formed atmosphere variable. clearly exhibit an excess due dust emission longward 5 micron;...

We present an analysis of optical and infrared spectra the recurrent nova RS Oph obtained during between 2006 2009.The best fit to spectrum for September 28 gives T eff = 3900 K log g 2.0, while 0.0 we find 4700 K, a comparison with template stellar provides ∼ 4500 K.The observed spectral energy distribution (SED), intensities emission lines, vary on short ( < 1 day) time-scales, due disc variability.We invoke simple one-component model accretion disc, hot boundary layer, high (∼ 3.9 × 10 -6...

We present an analysis of a high-resolution (R≃ 40 000) infrared spectrum the RS Oph secondary around first overtone CO bands, obtained in 2008 May on Gemini-South 8 m telescope. The 12CO and 13CO bands are well resolved, we compute synthetic spectra to determine 12C/13C ratio. find ≃ 16 ± 3, consistent with interpretation as red giant which has evolved beyond dredge-up phase evolution.

We present the results of modelling 0.45–1m spectral energy distribution V838 Mon for 2002 November. Synthetic spectra were calculated using NextGen model atmospheres Hauschildt et al. (1999, ApJ, 512, 377), which incorporate line lists H2O, TiO, CrH, FeH, CO, and MgH, as well VALD atomic list. Fits to observed show that, in November, effective temperature was approximately K. Our theoretical a comparatively weak dependence on . Preliminary analysis hot star together with shows it be normal...

We present a determination of the effective temperatures, iron abundances, and microturbulent velocities for pseudophotosphere V838 Mon on 2002 February 25, March 2 26. Physical parameters line forming region were obtained in framework self-consistent approach, using fits synthetic spectra to observed wavelength range 5500-6700A. Tef = 5330, 5540 4960 K, 2, 26, respectively. The abundance log N(Fe)=-4.7 does not appear change atmosphere from 25 2002.

We selected a sample of post-AGB candidates in the Magellanic Clouds on basis their near- and mid-infrared colour characteristics. Fifteen most optically bright were observed with South African Large Telescope order to determine stellar parameters thus validate or discriminate nature as objects Clouds. The spectral types absorption-line estimated according MK classification, effective temperatures obtained by means atmosphere modelling. Emission-line classified fluxes emission lines presence...

The overview of the content an Archive ofthe spectral photographic observational data stored at theMAO NAS Ukraine in 1965–1985 is presented. Beingthe part UkrVO Joint Digitized Archive, this archivecontains 50,000 spectra mostly variable stars.The material (glass astroplates)was obtained by 70-cm reflector AZT-2 (MAO ofUkraine, Kyiv), 60-cm Zeiss telescope Mount Ter-skol (North Caucasus, Russia), and 1-m theMount Sanglok (Institute Astrophysics, Tajikistan)equipped with spectrographs UAGS a...

We present an analysis of the red giant component recurrent nova V3890 Sgr, using data obtained before and after its 2019 eruption. Its effective temperature is $T_{\rm eff}=3050\pm$200 K for $\log{g}=0.7$, although there are modest changes in eff}$. There overabundance both carbon ($0.20\pm0.05$~dex) sodium ($1.0\pm0.3$~dex) relative to their solar values, possibly result ejecta from 1990 eruption being entrained into photosphere. find $^{12}$C/$^{13}$C $=25\pm2$, a value similar that found...

Abstract We present Spitzer spectroscopy of the recurrent nova RS Ophiuchi obtained on several occasions between 2006 and 2009. The spectra show variability in silicate dust features at 9.7 μm 18 μm, which form wind red giant system. fit with D usty models find changes temperature, due to luminosity central source. mass-loss rate secondary is a few 10 −7 M ⊙ yr −1 , typical its type.