With the aim of investigating the resonance system of NO, equivalent width calculations have been made for the 213.575 nm, O1(31.5) line of the 1-0 band of y-system of NO for the photospheric HSRA model, and for the line 214.012 nm, O1(25.5) line of the same band system for Zwaan's (1974) sunspot model.Calculations show that 3,-band system would not show up in the photospheric spectrum whereas a sunspot model yields an equivalent width of 72 m~, suggesting that sunspots may provide relatively more favourable conditions for the detections of the resonance systems of some abundant molecules in the inaccessible ultraviolet region.

In the present investigation, we have carried out power spectrum analysis of sunspot number and great hard X-ray (GHXR) burst (equal to or greater than i0,000 counts per second) for a period of about 6 years. The GHXR bursts show a periodicity of about 155 days. On the other hand, sunspot numbers do not show any periodicity. The GHXR burst periodicity confirms the existence of a 152-158 days periodicity in the occurrence of solar energetic events. Further, the GHXR bursts are showing periodicity independently indicating that the GHXR bursts are a separate class of X-ray flares.

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Here we have carried out a power-spectrum analysis of solar nuclear gamma-ray (NGR) flares observed by SMM and HINOTORI satellites. The solar NGR flares show a periodicity of 152 days, confirming the existence of a 152-158 days periodicity in the occurrence of solar activity phenomena and also indicating that the NGR flares are a separate class of solar flares . The power-spectrum analysis of the daily sunspot areas on the Sun for the period 1980-1982 shows a peak around 159 days while sunspot number data do not show any periodicity (Verma and Joshi, 1987). Therefore, only sunspot area data should be treated as an indicator of solar activity and not the daily sunspot number data. l.IntroductionDuring the solar cycle 21, 152-158 day periodicity was detected in the rate of occurrence of energetic solar flares. This periodicity was first pointed out by Rieger et al. (1984) from the occurrence rate of solar gamma-ray (GR) bursts detected above 300 keY . Rieger et al. (1984) found that soft X-ray bursts also show a 152 day periodicity in the rate of GOES events with classification > M 2.5. Kiplinger et al. (1984) studied larger sample of 6775 solar hard X-ray (HXR) bursts above 30 key and found a 158 day periodicity. Ichimoto et al. (1985) found similar periodicity from H-alpha flare data observed during solar cycles 20 and 21.Bogart and Bai (1985) carried out a power-spectrum study of microwave (MW) emission bursts observed on 1 GHz for the period 1966-1983 and found a 152 day periodicity. Verma and Joshi (1987) analysed strong HXRbursts and sunspot number data for the period 1980-1984 and found a 155 day periodicity in case of strong HXR events and no periodicity in case of sunspot number data. Wolff (1983) carried out Fourier analysis of the variation of the mean monthly sunspot numbers for the period 1799-1979 and found that the most prominent peak below 200 days is 155.4 days, remarkbly close to the period for flares in cycle 21.In the present work, we have carried out a power-spectrumanalysis of daily solar NGR flares, sunspot area data and umbral area data. Observational Data, Analysis and ResultsIn the present investigation we have used data of flares observed by SMM satellite during the period 1980-1985 and HINOTORI satellite during 1981 -1982 The SMM satellite recorded 92 NGR flares (Cliver et ai.,1989).

We present a complete spatial and dynamical study of the poorly populated stellar system ESO65SC03. The radial distribution of the system gives a core and cluster radii of 1.10 ± 0.63 and 5.36 ± 0.24 arcmin, respectively. The SNDP does not show any clear enhancement of the surface stellar number density between the stars of the system and the field regions. We derive the optimum isochrone solution for a particular grid size in the CMD using the statistical cleaning procedure. Using the statistically cleaned CMDs, we find the distance modulus, (m − M) 0 , and reddening, E(B − V ), of the system to be 11.8 ± 0.2 and 0.45 mag, respectively. The mean proper motion of this system is −5.37 ± 0.81 mas yr −1 and 0.31 ± 0.40 in RA and DEC directions, respectively. The mean proper motion of this system is found to be almost similar to the field region. The mass function for the brighter stars is found to be too high for the system to be an open cluster. These combined results place constraints on whether stellar system ESO65SC03 is a POCR or an Asterism. Our understanding is that the ESO65SC03 is in a stage of POCR by losing their main-sequence stars in the dynamic evolution processes.

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The basic physical parameters of a poorly studied open cluster NGC 110 and an unstudied open cluster DOLIDZE 14 are estimated in the present study using the archival P P MXL and W ISE catalogues. The radius of both the clusters are estimated by fitting the modified King's empirical model on their stellar density profiles. The other basic parameters of the clusters such as distance, reddening, and age are obtained by visual fitting of the Marigo's solar metallicity isochrone on their IR colour-magnitude diagrams (CMDs). The mean-proper motion of the clusters are estimated through the individual proper motion of probable members identified through the dynamical and statistical methods. The archival catalogues (JHKW 1 W 2 ) are constructed for both the clusters by compiling the extracted data from the P P MXL and W ISE catalogues. The various colour-excesses, such as E(J −H), E(H −K) and E(W 1 − W 2 ), are estimated using the best fit theoretical isochrone on the (J − H) − H, (H − K) − H and (W 1 − W 2 ) − H CMDs, respectively. The ratios of various infrared colours of the clusters are obtained through their two-colour diagrams. We also identify the most probable members in these clusters by estimating spatial, kinematic and spatio-kinematic probabilities of stars within the cluster. A correlation between the E(H −K) and E(W 1 −W 2 ) is also established.