مقاله انگلیسی رایگان در مورد تحقیق در مورد نیمکره جنوبی بارش های شهابی – الزویر ۲۰۱۸

Meteor showers identify streams of meteoroids that approach from a similar direction and presumably originated from the same parent object (Jenniskens, 2017). In recent years, over 300 meteor showers have been identified, of which 112 have been established and are certain to exist. A Working List of identified showers is maintained by the IAU Meteor Data Center (Jopek & Kanuchova, 2017). The southern hemisphere meteor showers are not as well mapped as those on the northern hemisphere. Only 27 out of 112 established showers have negative declinations. The first of these showers, such as the Phoenicids (IAU#256, PHO), were initially identified by visual observers in South Africa, Australia and New Zealand. Early visual observations were summarized by Ronald Alexander McIntosh (1904–۱۹۷۷), an amateur astronomer and journalist with the New Zealand Herald. His 1935 paper “An index to southern hemisphere meteor showers” identified 320 showers derived from visually plotted meteor paths on star charts (Fig. 1A). However, many proposed showers were defined by a statistically unreliable grouping of meteor tracks traced to a diffuse radiant. Southern hemisphere showers were mapped by radar, starting in the late 1950’s, by W. Graham Elford and his students Alan A. Weiss and Carl Nilsson at Adelaide in Australia (Weiss 1955, 1960a, b; Nilsson, 1964, Gartrell & Elford, 1975). More recently, a new type of meteor radar was developed in Adelaide, which are now deployed at many locations around the globe. Single-station derived southern hemisphere meteor shower radiants were published by Younger et al. (2009). A history of the Adelaide group is given in Reid & Younger (2016). At the same time, Clifford D. Ellyett and his student Colin S. Keay observed meteors by radar in Christchurch, New Zealand (Ellyett & Keay, 1956; Ellyett et al., 1961). Keay continued observations from Newcastle, Australia (Rogers & Keay, 1993). In the 1990’s, the AMOR radar in Christchurch, New Zealand, provided orbital data for the six strongest meteor showers (Galligan, 2001, 2003; Galligan & Baggaley, 2004, 2005). We report here on results from a CAMS-type video-based meteoroid orbit survey (Jenniskens et al., 2011) conducted in New Zealand in 2014–۲۰۱۶٫ The capability of the technique was demonstrated in earlier small scale video-based meteoroid orbit surveys in the southern hemisphere (e.g., Jopek et al., 2010; Molau & Kerr 2014). The newly detected showers are compared to recent results from a southern hemisphere radar orbital survey conducted with the Southern Argentina Agile MEteor Radar (SAAMER) (Pokorny et al., 2017). It is found that video-based and radar-based observations detect, in general, different streams.