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X-Ray, UV and Optical Observations of Classical Cepheids: New Insights into Cepheid Evolution, and the Heating and Dynamics of Their Atmospheres
Guinan, Edward F.; Engle, Scott G.
To broaden the understanding of classical Cepheid structure, evolution and atmospheres, we have extended our continuing secret lives of Cepheids program by obtaining XMM/Chandra X-ray observations, and Hubble space telescope (HST) / cosmic origins spectrograph (COS) FUV-UV spectra of the bright, nearby Cepheids Polaris, δ Cep and β Dor. Previous s…
IUE Spectra of Seyvert 1 Galaxy NGC 7469- BLR Characteristics of NGC 7469
Hyung, Siek; Son, Dong-Hoon
From the line ratios of Si III] 1892 to C III] 1909 (Feibelman & Aller 1987), we estimated the BLR electron densities and their changes of Seyfert 1 galaxy NGC 7469 using IUE spectra observed from June 11 to July 29, 1996 (Wanders et al. 1997). We separated blended Si III] and C III] lines using the STARLINK/DIPSO and measured their fluxes wit…
Starspot Model of RS CVn Type Binary SZ PSC
Kang, Young-Woon
The emission lines of the ultraviolet region and the light curves of the optical region have been analyzed to investigate the distorted light curves of SZ Psc. The Mg II emission lines of the IUE spectra confirmed that the chromospheric activity of SZ Psc occurs on the K1 IV star. The distorted light curves in the optical region have been analyzed…
Determination of Stellar Surface Temperature Using Ultraviolet Spectra
Choi, Young-Jun; Han, Wonyong; Kang, Young Woon +3 more
Color indexes and effective temperatures for 25 standard stars have been determined as a pilot project which show a relationship between color index and effective temperature in ultraviolet region. The effective temperature was determined by comparing energy distribution curves derived from the IUE low dispersion spectra with Kurucz atmosphere mod…
The Chromospheric Activity on V711 Tau
Kang, Young-Woon
The relationship between Mg ¥± emission line and light variation of V711 Tau has been derived to investigate the chromospheric activity on V711 Tau. First, a shape of an optical light curve was compared with that of ultraviolet constructed from the IUE low resolution spectra. Second, the intensities of Mg ¥± k emission lines have been reduced from…
SS Lac in Open Cluster NGC 7209
Kang, Young Woon
We present IUE observations in far ultraviolet region for SS Lac in open cluster NGC 7209. The IUE short wavelength spectrum and long wavelength spectrum were merged to produce an energy distribution curve between 1200A and 3200A. The curve has been unreddened to take out reddening effect. Then the surface temperature, gravity and abundance of SS …
U Energy Distribution of AZ Cassiopeiae
Kang, Young-Woon
The IUE low dispersion spectra of AZ Cas have been analyzed for line identifications and energy distribution in ultraviolet region. Highly ionized atoms, Si IV and C IV are identified. We could infer a temperature range of the B star between 15,000K and 20,000K. The energy density distribution shows a hump between IUE short wavelength and long wav…
Determination of Wind Parameters by the Method of Differential Corrections
Kim, You-Kyung; Kang, Young Woon
This paper describes a method for the determination of wind parameters as mass-loss rate, wind velocity, stochastic velocity in Zeta Aurigae type binaries. We have modified the Baade's (1989) computer code to analyze the wind parameters of Zeta Aurigae type binaries according to the least squares criterion. The modified program adjusts the wind pa…
Ultraviolet Spectrophotometry of VV Cephei
Kang, Young Woon
The IUE archival spectra of VV Cephei were collected to investigate the eclipse nature in the ultraviolet. The temperature of the B star has been determined, as approximately 30000K, based on the flux distributions during egress. Light curves of VV Cephei were reduced from the spectrophotometry of the IUE archival spectra. Three light curves at th…
M ¥± Line Variation of 32 Cygni
Kang, Young Woon
The Mg ¥± lines have been extracted from the IUE archival spectra of 32 Cygni to investigate the effect of the atmospheric eclipse. The UV light curve has been reduced from the continuum flux at the center wavelength of 2807.5 Å in the IUE spectra. The equivalent width of the Mg ¥± k absoption line has been measured for each spectra. The results o…