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S . Gunasekera , Janaka Adassuriya , I . Medagangoda Arthur C Clarke Institute Sri Lanka

Spectroscopic Observations of Novae V1065 CENTAURI and V1280 SCORPII Using 45 cm Cassegrain Telescope at Arthur C Clarke Institute, Sri Lanka. S . Gunasekera , Janaka Adassuriya , I . Medagangoda Arthur C Clarke Institute Sri Lanka .

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S . Gunasekera , Janaka Adassuriya , I . Medagangoda Arthur C Clarke Institute Sri Lanka

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  1. Spectroscopic Observations of Novae V1065 CENTAURI and V1280 SCORPII Using 45 cm Cassegrain Telescope at Arthur C Clarke Institute, Sri Lanka S. Gunasekera, JanakaAdassuriya, I. Medagangoda Arthur C Clarke Institute Sri Lanka UN Workshop on BSS & IHY 2007 held on September 21-25, 2009 in Daejeon, South Korea

  2. 45cm Telescope and Spectrograph at ACCIMT Monk-Gillieson type Spectrograph 45cm reflector donated by Japanese Government in 1996

  3. Telescope Specifications • Effective Aperture 45 cm • Effective Focal Length 5400 mm • F Number f/12 • Theoretical Resolving Power 0.31 arcseconds • Maximum Visual Magnitude 15 Spectrograph & CCD Specifications • Spectral Resolution at H-α (λ/Δλ) = 22000 • Plane reflective grating 1200 grooves/mm • SBIG ST 7 CCD camera (765 x 510 pixels)

  4. What is a Nova ? • Nova is a star that suddenly increases its light output and then • fades away to its former in few months or years. • Hydrogen-rich material accretes on the white dwarf’s from its • red-dwarf companion. • White dwarf’s masses ranges from 0.5 – 1.4 solar mass. • The material gradually accumulates and compressed rising the • temperature. • When temperature is 20 million K, Hydrogen ignited by CNO • cycle. • The nuclear reactions runs away expanding the shell.

  5. Classification of Nova Spectroscopic Classification of Nova • He/N type Nova (R. E. Williams) • Fe II type nova (R. E. Williams) Adopted from R.E. Williams, AJ 1992

  6. Classifications of Nova Light Curves t2 t3 t2 - Time for light curve to decay 2 magnitudes from peak t3 - Time for light curve to decay 3 magnitudes from peak Image reference http://www.AAVSO.org.htm

  7. Objectives of the observation • Analyze the novae spectra in Hα (6563 ⁰A) region and explain the • structural variations of the profile with the time. • Compare and contrast the profiles of two novae. • Estimate the distance to the nova using light curve.

  8. IRAF PC version( RedHat Linux) 2.12.2 is used to reduce the • spectroscopic raw data. • Data reduction steps include: • Dark subtraction • Flat field correction • Wavelength calibration (reference Fe-Ne) • Normalization to stellar continuum

  9. Spectroscopic Observations Hydrogen Alpha line at 6563 A⁰ Resolution 0.3 A⁰/Pixel H-α profile of V1065 CEN 6 days after maximum H-α Profiles of V1280 SCO 4 days after maximum

  10. 5 4 3 2 1 -4000 -2000 0 2000 4000 Velocity (km/s) 3.5 3.0 2.5 2.0 1.5 1.0 -4000 -2000 0 2000 4000 Velocity (km/s) 5 4 3 2 1 -4000 -2000 0 2000 4000 Velocity (km/s) H-α profiles of V1065 CEN 31JAN (6 days) 9FEB (15 days) 20FEB (26 days)

  11. -4000 -2000 0 2000 4000 Velocity (km/s) Hα profiles for V1065 CEN 20FEB (26 d) 9FEB (15 d) 31JAN (6 d)

  12. Blending Hα profiles of V1065 CEN 20FEB (26 days) Hα (6563) N II (6583) O II (6539)

  13. Analysis of Periodic Variations of V1065 CEN • IB/IR ratio changes drastically • Slight drop of intensity after 15 days and increased again • Blue component moves towards the line center while the red is moving away • from the line center • N II line immerged after 26 days shows the nova begins nebular stage

  14. 2.00 1.75 1.50 1.25 1.00 0.75 -4000 -2000 0 2000 4000 Velocity (km/s) H-α profile of V1280 SCO 20FEB (4 days)

  15. 5 2.00 4 1.75 3 1.50 2 1.25 1 1.00 -4000 -2000 0 2000 4000 Velocity (km/s) 0.75 -4000 -2000 0 2000 4000 Velocity (km/s) V1065 CEN V1280 SCO Nova V1065 CEN is He/N-type spectra which characterize a broad (Gaussian FWHM 49 oA), saddle shaped asymmetric H profile without absorption components. The emission causes by discrete shell. Nova V1280 SCO is Fe II type nova with prominent P-Cyg absorption and narrow emission line (Gaussian FWHM 26 oA) which evidences a wind-like structure.

  16. 2.00 1.75 1.50 1.25 1.00 0.75 -4000 -2000 0 2000 4000 Velocity (km/s) H-α profile of V1280 SCO 20FEB (4 days)

  17. P-Cyg Profile 3 2 2 1 2 Line of site 3 λ 1 λ₀

  18. 5 2.00 4 1.75 3 1.50 2 1.25 1 1.00 -4000 -2000 0 2000 4000 Velocity (km/s) 0.75 -4000 -2000 0 2000 4000 Velocity (km/s) Observation of P-Cyg Structure V1065 CEN V1280 SCO 20FEB (4 days) 31JAN(6 days) 716 km/s 2300 km/s • The expansion velocities to the direction of line of site were taken from the minima of P-Cyg profile. • Expansion velocity for V1065 CEN = 2300 km/s • Expansion velocity for V1280 SCO = 716 km/s

  19. Absorption versus Emission lines of Novae Line of sight λ₀ Red Giant White Dwarf λ Line of sight λ₀ The main difference between the spectra of V1065 CEN and V1280 SCO is the absence of prominent P-Cyg profile in V1065 CEN. This can be explained by the inclination to the line of site of the two systems and the equatorial bulge.

  20. Photometric Analysis • The photometric analysis was done by using the light curve data. • The location of the Arthur C Clarke Observatory inappropriate for photometric • analysis. • The light curve data were taken from American Association of Variable Star • Observers (AAVSO) website http://www.aavso.org/data/download/

  21. Light Curves for V1065 CEN mB mv JD 2454000+ JD 2454000+ • MATLAB curve fitting tool is used to fit the curves to the data points. • The light curve of V1065 CEN is Batype. • t2 and t3 were taken from the light curves. • Absolute magnitudes for V band (Mv) and for B band (MB) were calculated using the • Maximum Magnitude /rate of decline (MMRD) relationship. Where M – absolute magnitude n – 2 or 3 an and bn are constants M = bn log tn + an Light curve data archived from www.aavso.org

  22. . Basic Parameters of Nova V1065 CEN • The distance estimation by Andrew Helton, University of Minnesota, is 7.9 kpc which • is close to our estimation.

  23. Light Curve for V1280 SCO Visual magnitude JD 2454000+ • The light curve of V1280 SCO is Aotype. Light curve data archived from www.aavso.org

  24. Basic Parameters of Nova V1280 SCO

  25. White Dwarf Mass White dwarf mass is estimated by the relationship given by Mario Livio ( AJ 1991) MBmax ≈ -8.3 – 10 log (Mwd/Mo) where Mo is solar mass For nova V1065 CEN Mwd ≈ 0.88 Mo For nova V1280 SCO Mwd ≈ 1.09 Mo

  26. Conclusions • Hα Profile of V1065 CEN is originated by He/N type nova • Broad emission line (Gaussian FWHM = 49 oA) • High expansion velocity (2500 km/s) • Shape of the profile • Photometric analysis shows that the nova V1065 CEN is comparatively slow (t2=21 d) • The unaltered Hα profiles • Mwd = 0.88 Mo Comparatively low mass white dwarf reveals the low absolute • magnitude (Mv = -7.58) • Hα profile of V1280 SCO is originated by Fe II type nova • Narrow emission line (Gaussian FWHM = 26 oA) • Low expansion velocity (716 km/s) • Shape of the profile • Photometric analysis shows that the nova V1280 SCO in very fast (t2= 12 d) • Hα profile could not be observed after few days • Mwd = 1.09 Mo comparatively high mass white dwarf evolves very quickly raising • the absolute magnitude up to Mv = -8.7

  27. Conclusions • Different geometry of the binary system affects to make the prominent P-Cyg • profile in Hα region. • The coincidence line of sight and the equatorial bulge is also very important for • the presence of P-Cyg structure in V1280 SCO. • The absence of prominent P-Cyg structure in V1065 CEN reveals the line of sight • and the disk of accretion is apart from some extent.

  28. Thank You

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