Do you want to publish a course? Click here

Observations of red-giant variable stars by Aboriginal Australians

97   0   0.0 ( 0 )
 Added by Duane Hamacher
 Publication date 2017
  fields Physics
and research's language is English




Ask ChatGPT about the research

Aboriginal Australians carefully observe the properties and positions of stars, including both overt and subtle changes in their brightness, for subsistence and social application. These observations are encoded in oral tradition. I examine two Aboriginal oral traditions from South Australia that describe the periodic changing brightness in three pulsating, red-giant variable stars: Betelgeuse (Alpha Orionis), Aldebaran (Alpha Tauri), and Antares (Alpha Scorpii). The Australian Aboriginal accounts stand as the only known descriptions of pulsating variable stars in any Indigenous oral tradition in the world. Researchers examining these oral traditions over the last century, including anthropologists and astronomers, missed the description of these stars as being variable in nature as the ethnographic record contained several misidentifications of stars and celestial objects. Arguably, ethnographers working on Indigenous Knowledge Systems should have academic training in both the natural and social sciences.



rate research

Read More

A major focus of the archaeoastronomical research conducted around the world focuses on understanding how ancient cultures observed sunrise and sunset points along the horizon, particularly at the solstices and equinoxes. Scholars argue that observations of these solar points are useful for developing calendars, informing ritual/ceremonial practices, and predicting seasonal change. This is the foundation of the Eurocentric four-season Julian (and later Gregorian) calendar. Famous examples include Stonehenge, Newgrange, Chichen Itza, and Chankillo. Studies at these and other sites tend to focus on solar point observations through alignments in stone arrangements, and the orientations of monuments. Despite the ongoing study of Indigenous Knowledge in Australia revealing a wealth of information about Aboriginal and Torres Strait Islander observations and interpretations of solar, lunar, and stellar properties and motions, very little has been published about the importance and use of solar point observations. The authors examine this topic through four case studies, based on methodological frameworks and approaches in ethnography, ethnohistory, archaeology, and statistics. Our findings show that Aboriginal and Torres Strait Islander people observe the solstices and other significant sunrise/sunset points along the horizon for timekeeping and indicating seasonal change - but in ways that are rather different to the four-season model developed in Western Europe.
The canopy of stars is a central presence in the daily and spiritual lives of Aboriginal Tasmanians. With the arrival of European colonists, Tasmanian astronomical knowledge and traditions were interrupted and dispersed. Fragments can be found scattered in the ethnographic and historical record throughout the nineteenth century. We draw from ethnohistorical documents to analyse and reconstruct Aboriginal astronomical knowledge in Tasmania. This analysis demonstrates that stars, the Milky Way, constellations, dark nebula, the Sun, Moon, meteors, and aurorae held cultural, spiritual, and subsistence significance within the Aboriginal cultures of Tasmania. We move beyond a monolithic view of Aboriginal astronomical knowledge in Tasmania, commonly portrayed in previous research, to lay the groundwork for future ethnographic and archaeological fieldwork with Aboriginal elders and communities.
The oral traditions of Aboriginal cultures across Australia contain references to the presence of multiple Suns in the sky at the same time. Explanations of this have been largely regarded as symbolic or mythological, rather than observations of natural phenomena. In this paper, we examine oral traditions describing multiple Suns and analyse interpretations that could explain them. Our analysis of the oral traditions concludes that descriptions of multiple Suns fall into two main categories: one describing the changes in the path of the Sun throughout the year, and the other describing observations of parhelia, an atmospheric phenomenon known as Sun dogs that creates an optical illusion of multiple Suns in the sky at once. This analysis shows how Aboriginal people pay close attention to natural phenomena, assign them social meaning, and incorporate them into oral tradition.
Period-luminosity (PL) relations of variable red giants in the Large (LMC) and Small Magellanic Clouds (SMC) are presented. The PL diagrams are plotted in three planes: logP-K_S, logP-W_{JK}, and logP-W_I. Fourteen PL sequences are distinguishable, and some of them consist of three closely spaced ridges. Each of the sequences is fitted with a linear or quadratic function. The similarities and differences between the PL relations in both galaxies are discussed for four types of red giant variability: OGLE Small Amplitude Red Giants (OSARGs), Miras and Semiregular Variables (SRVs), Long Secondary Periods (LSPs) and ellipsoidal variables. We propose a new method of separating OSARGs from non-variable stars and SRVs. The method employs the position in the reddening-free PL diagrams and the characteristic period ratios of these multiperiodic variables. The PL relations for the LMC OSARG are compared with the calculated relations for RGB models along isochrones of relevant ages and metallicities. We also compare measured periods and amplitudes of the OSARGs with predictions based on the relations valid for less luminous solar-like pulsators. Miras and SRVs seem to follow PL relation of the same slopes in the LMC and SMC, while for LSP and ellipsoidal variables slopes in both galaxies are different. The PL sequences defined by LSP variables and binary systems overlap in the whole range of analyzed wavebands. We put forward new arguments for the binary star scenario as an explanation of the LSP variability and elaborate on it further. The measured pulsation to orbital period ratio implies nearly constant ratio of the star radius to orbital distance, R/A=0.4, as we find. Combined effect of tidal friction and mass loss enhanced by the low-mass companion may explain why such a value is preferred.
The successful launches of the CoRoT and Kepler space missions have led to the detections of solar-like oscillations in large samples of red-giant stars. The large numbers of red giants with observed oscillations make it possible to investigate the properties of the sample as a whole: ensemble asteroseismology. In this article we summarise ensemble asteroseismology results obtained from data released by the Kepler Science Team (~150,000 field stars) as presented by Hekker et al. (2011b) and for the clusters NGC 6791, NGC 6811 and NGC 6819 (Hekker et al. 2011a) and we discuss the importance of such studies.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا