Radionuclide partitioning across great lakes natural interfaces

Several water and surface microlayer samples from Lake St. Clair, the Niagara River, and the North Shore of Lake Ontario collected during 1983–1986 have been assayed for a variety of radionuclides. In addition, the foam accumulating in the pool just below Niagara Falls was also analyzed and found to be the most efficient aqueous phase collector of¹³⁷Cs,²¹⁰Pb, and²²⁶Ra.The order of radioisotope specific activities from highest to lowest is: Lake Ontario sediment, Niagara River suspended solids, Niagara River foam, surface microlayer water, and subsurface water. Radiological dose rates to the sediments from¹³⁷Cs,²²⁶Ra, and²²⁸Th total about 5 mGy/y.     

On the gamma system of nitric oxide in sunspots

With the aim of investigating the resonance system of NO, equivalent width calculations have been made for the 213.575 nm, Q ₁(31.5) line of the 1–0 band of -system of NO for the photospheric HSRA model, and for the line 214.012 nm, Q ₁(25.5) line of the same band system for Zwaan's (1974) sunspot model.Calculations show that -band system would not show up in the photospheric spectrum whereas a sunspot model yields an equivalent width of 72 mÅ 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.     

芦山MS7.0地震前天体引潮力和OLR异常

2013年4月20日在我国四川省芦山（30.284o N, 102.955o E）发生MS7.0地震,计算该地区潮汐变化,地震时刻引潮力处于最低相位点,显示引潮力的诱震作用属于典型逆冲断层作用类型。以此潮汐周期为时间指示（4月12日~4月23日）,利用NOAA卫星地面长波辐射（OLR）数据资料分析全国范围地震前后热辐射值连续变化,结果显示：伴随潮汐演化,在全国范围（17°N-55°N ~ 73°E-155°E）内,震前OLR仅震中及其相关联断裂附近发生了显著而连续异常变化过程：在时间上经历了起始增温→异常加强→高峰→衰减→发震→平静的演化过程;在空间上异常位置与震中基本吻合,发展过程表现出沿断裂带由分散→汇聚→分散的破裂过程,与岩石应力加载破裂演化经历：初始微动破裂→扩张破裂→应力闭锁→地震爆发→平静阶段的力学过程完全吻合,显示天体引潮力对处于临界状态的活动断层具有诱发作用,而长波辐射异常是地震构造应力应变过程辐射表征。将引潮力与OLR异常结合在地震前兆研究中有一定的实用价值。     

Hα emission line morphologies in Markarian starburst galaxies

We present broad bandR and narrow band Hα emission line images of a sample of optically selected starburst galaxies from the Markarian lists. The emission line morphology is studied and global properties like luminosities, equivalent widths and star formation rates are derived. The radial distribution of Ha flux and the EW are determined using concentric aperture photometry on the emission line and the continuum images. Ha flux is generally found to peak in the nuclear region and fall off outwards. The EW is found to peak off-center in most of the cases implying that though the intensity of emission is maximum at the nucleus, the star formation activity relative to the underlying continuum often peaks away from the center in Markarian starburst galaxies.     

Coronal mass ejection of 4 April 2000 and associated space weather effects

The effects of a Halo Coronal Mass Ejection (CME) erupted on 4 April 2000 are studied and reported here. The effect of such CME on the interplanetary medium (IPM) is sensed by the Interplanetary Scintillation (IPS) recorded at Rajkot. The Solar Observations of this CME and associated events, like Solar Energetic Particles (SEP) and flare, are presented. CME events with high speeds and negative magnetic field components have higher possibility of penetrating the earth's shield, viz. the magnetosphere. The 4 April 2000 CME with a high speed and southward component of IMF produced a big geomagnetic storm with D_st reaching . Simultaneous ionospheric effects in F layer heights and auroral observations are reported. Such events are important in Space Weather Studies as these pose hazards to space operations including satellite communications and surveillance systems.     

Study of the galactic cluster NGC 6823

PhotoelectricUBV magnitudes have been determined for 41 stars in NGC 6823. The reddening across the cluster field is determined and found that it varies fromE(B-V)=0.60 to 1.16 mag. The true distance modulus to the cluster is estimated at 12.7±0.3 mag. It is found that cluster stars are not co-equal in age.     

On the periodicities of sunspots and solar strong hard X-ray bursts

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 10,000 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.