Monitoring of the Yellow Hypergiant Rho Cas: Results of the High-Resolution Spectroscopy During V.G. Klochkova (SAO RAS, Nizhnij Arkhyz, Russia) I.A. Usenko (Dpt. Of Astronomy, Odessa Naional University, Odessa, Ukraine)

Mean features 1) High-mass stars with limiting high luminosity (M v > -8 m ); 2) High rate of mass loss; 3) Dynamical instability in their atmospheres (pulsations); 4) Presence of extensive circuumstellar shells; 5) «Shell episodes» demonstration

Hertzsprung-Russel diagram for the brightest stars

Mean Parameters = 4.4 mag ; R = R sun = L sun ; Teff = K Mass = 40 M sun Age = 4-6 Myr Spectral Type: Mass loss: K0 - before M sun F8 Ia M sun K-M M sun F8-G2 Ia0 - now M sun - now

Related objects V509 Cas (HR 8752) Sp. G0 - G5 Ia0 T eff = 4000 K; log g = -2.0; V t = 11.0 km/s (Luck, 1975) T eff = 5478 K; log g = 0.9 (Fry & Aller, 1975) V 766 Cen (HR 5171) Sp. G8 Ia0 T eff = 4893 K; log g = 0.00 [Fe/H] = (Warren, 1973) V382 Car (HR 4337) Sp. G0 Ia0 T eff = 5866 K; log g = 0.5; V t = 7.0 km/s; [Fe/H] =+0.05 (Usenko et al., 2011) V1302 Aql (IRC ) Sp. F8 Ia0 OH-maser

Observations 6m BTA telescope SAO RAN echelle-spectrograph NES in Nesmit focus with CCD 2048 x 2048 R = 60000; S/N = 100 Spectral ranges: Extraction: A ECHELLE context from MIDAS A Processing: A DECH 20

— V brightness curve of Cas (fi.lled symbols) compared in the top panel to the radial velocity curve (dotted line), observed over the past 8.5 yr ( ) (Loebel et al., 2003, ApJ 583, 923)

Fragment of Rho Cas spectrum

Effective temperature T eff were determined using spectroscopic criteria (Kovtuykh, 2007, MNRAS 378, 617) by the method based on the depth ratios of selected pairs of spectral lines most sensitives to the temperatuures.

Spectral lines used in analysis 1) Symmetric lines ( in most cases - single moderate intensity lines of metals). 2) Short-wave components of splitted low- excited absorptions. 3) Long-wave components of splitted low- excited absorptions. 4) Neutral hydrogen lines (alpha & beta).

List of splitted lines in Rho Cas spectra Element Lambda X low, eV Ti II Fe I Ti II Fe I Ba II Fe I Fe I Fe I Fe I Ba II Fe I Ba II Fe I Ba II Fe I

Heliocentrical Radial velocity measurements V r (sym) -symmetric; V r (blue)- short-wave; V r (red) - long-wave; V r (HI) - neutral hydrogen absorptions Date V r (sym) NL V r (blue) NL V r (red) NL V r (HI) (B) (B) (A) (A) (B) (A) (A) (A)

Ba II 6141 A line profile 1-HJD (6744 K); 2-HJD (6322 K); 3-HJD (6610 K); 4-HJD (6044 K); 5-HJD (5777 K)

D2 Na I 5889 A line profile 1-HJD (6744 K); 2-HJD (6322 K); 3-HJD (6610 K); 4-HJD (6044 K); 5-HJD (5777 K)

D2 Na I 5889 A line profile from Loebel et al. (2003)

Central Part of H alpha line profiles 1-HJD (6744 K); 2-HJD (6322 K); 3-HJD (6610 K); 4-HJD (6044 K); 5-HJD (5777 K)

H alpha line profiles from Loebel et al. (2003)

Dependence of V r measured by absorption core from its residual intensity Dots - separate absorptions of symmetrical lines of metals; squares - short-wave components of splitting absorptions; circles - long-wave ones; cross - HI absorption components; stars - short-wave and long- wave D Na I lines components; dashed line - V sys = -47 km/s

Dependence of V r measured by absorption core from its residual intensity Dots - separate absorptions of symmetrical lines of metals; squares - short-wave components of splitting absorptions; circles - long-wave ones; cross - HI absorption components; stars - shor-twave and long- wave D Na I lines components; dashed line - V sys = -47 km/s

Dependence of V r measured by absorption core from its residual intensity Dots - separate absorptions of symmetrical lines of metals; squares - short-wave components of splitting absorptions; circles - long-wave ones; cross - HI absorption components; stars - short-wave and long- wave D Na I lines components; dashed line - V sys = -47 km/s

Atmosphere parameters and metallicity T eff = 6000 K; log g = 0.25; [Fe/H] = (Boyarchuk & Lyubimkov, 1983, Izv. Krym. Astroph. Obs 66, 130) [Na/H] = +0.47; log M/M sun = 1.42 (Takeda & Takada-Hidai, 1994, PASJ 46, 395)

Chemical Composition Rho Cas V382 Cas Teff = 6174\pm43 K; log g = 1.0; Teff = 5866\pm47 K; log g = 0.5; Vt = 9.30 km/s Vt = 7.00 km/s Element [E/H] Sigma NL [E/H] Sigma NL C I O I Na I Mg I Si I S I Ca I

Chemical Composition Rho Cas V382 Cas Teff = 6174\pm43 K; log g = 1.0; Teff = 5866\pm47 K; log g = 0.5; Vt = 9.30 km/s Vt = 7.00 km/s Element [E/H] Sigma NL [E/H] Sigma NL Sc I Sc II Ti I Ti II V I V II Cr I Cr II Mn I

Chemical Composition Rho Cas V382 Cas Teff = 6174\pm43 K; log g = 1.0; Teff = 5866\pm47 K; log g = 0.5; Vt = 9.30 km/s Vt = 7.00 km/s Element [E/H] Sigma NL [E/H] Sigma NL Fe I Fe II Co I Ni I Cu I Zn I Sr I

Chemical Composition Rho Cas V382 Cas Teff = 6174\pm43 K; log g = 1.0; Teff = 5866\pm47 K; log g = 0.5; Vt = 9.30 km/s Vt = 7.00 km/s Element [E/H] Sigma NL [E/H] Sigma NL Y I Y II Zr II La II Ce II Pr II Nd II Eu II Gd II

Conclusions 1) During T eff demostrated changes within K. 2) The field of velocities has been analysed using the most number of single lines (some hundred ones in each spectrum) and splitted lines (about 12 ones on visual range). 3) The field of velocities has changed from date to date. In the single moments we can observe the radial velocity dependence from the residual line depth, i.e. the existence of velocity gradient in stelllar atmosphere.

Conclusions 4)In the long-wave components of splitted absorptional -forming region the velocity gradient take place too. At that its value has exceeded 15 km/s for single moments and the speed depended from line depth is the continuation of such dependence for single lines. 5) In the single date we can see the same gradient from short-wave components, but it is marked less and its value is no more 6 km/s.

Conclusions 6 ) Long-wave components of splitting absorptions are the usual photospherical ones, their forming region and velocity do not differ from the same for single absorptions. Short-wave components have formed in the circumstellar shell.

Conclusions 7) According to carbon, sodium and magnesium content, Rho Cas has gone through dredge-up in the red supergiant stage and is presently evolving blueward. Our [Na/H] = dex agrees excellent with theoretical value dex for star with mass about M sun from Takeda & Takada-Hidai (1994)