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H ii regions are ionized nebulae surrounding massive stars. They exhibit a wealth of emission lines that form the basis for estimation of chemical composition. Heavy elements regulate the cooling of interstellar gas, and are essential to the understanding of several phenomena such as nucleosynthesis, star formation and chemical evolution1,2. For over 80 years3, however, a discrepancy exists of a factor of around two between heavy-element abundances derived from collisionally excited lines and those from the weaker recombination lines, which has thrown our absolute abundance determinations into doubt4,5. Here we report observational evidence that there are temperature inhomogeneities within the gas, quantified by t2 (ref. 6). These inhomogeneities affect only highly ionized gas and cause the abundance discrepancy problem. Metallicity determinations based on collisionally excited lines must be revised because these may be severely underestimated, especially in regions of lower metallicity such as those recently observed with the James Webb Space Telescope in high-z galaxies7–9. We present new empirical relations for estimation of temperature and metallicity, critical for a robust interpretation of the chemical composition of the Universe over cosmic time.The authors report observational evidence that, within interstellar gas, there are temperature inhomogeneities affecting only highly ionized gas and causing the abundance discrepancy problem, and provide new empirical relations for estimation of temperature and metallicity. [ABSTRACT FROM AUTHOR]

We use Gemini GMOS-IFU observations of three luminous nearby Seyfert galaxies (Mrk 79, Mrk 348, and Mrk 607) to estimate the electron temperature (T e) fluctuations in the inner 0.4–1.1 kpc region of these galaxies. Based on T e determinations through the [O  iii ]λ5007/λ4363 emission line ratio of each spaxel, temperature variations are quantified by computing the integrated value of the temperature fluctuation parameter (t 2) projected in the plane of the sky |$t_{\rm A}^{\rm 2}$|⁠ , for the first time in active galactic nuclei (AGNs). We find |$t_{\rm A}^{\rm 2}$| values of 0.135, 0.039, and 0.015 for Mrk 79, Mrk 348, and Mrk 607, respectively, which are of the same order or larger than the maximum values reported in star-forming regions and planetary nebulae. Taking into account that |$t_{\rm A}^{\rm 2}$| should be considered a lower limit of the total t 2 in the nebular volume, the results suggest that the impact of such fluctuations on chemical abundance determinations can be important in some AGNs. [ABSTRACT FROM AUTHOR]

This paper presents the results of an archaeoastronomical study of the Iberian Iron Age cave-sanctuary of Cueva Santa del Cabriel, near the town of Mira in the province of Cuenca, Castilla-La Mancha, central Spain, together with a review of the latest archaeological and ethnographical data about the site. We found that the cave's 12 m-long access corridor is oriented precisely along the summer solstice sunset, so that the north wall of the main gallery is partially illuminated by sunlight at this time. Although the cave was in use from the Late Chalcolithic, it became an important religious centre in the Iberian period. After an apparent hiatus during the Roman and Islamic occupations, its ritual use was re-established with the Christian Reconquista, especially from the fourteenth and fifteenth centuries, and it is now dedicated to the worship of the Virgin Mary. Popular pilgrimages to the cave have continued until the present day. The characteristics of modern traditions related to the cave can, however, be of great value in understanding ancient Iberian ritual practices. [ABSTRACT FROM AUTHOR]

This paper summarizes the most relevant results of a thorough archaeoastronomical study conducted since 1997 in several tens of Iberian archaeological sites, most of them located in the southeast of the Iberian Peninsula. We found that a substantial fraction of the sanctuaries studied, all of them dedicated to a feminine goddess, shows a marker of the sunrise or sunset on conspicuous elements of the horizon at the equinoxes or a date very close to it, possibly the temporal midpoint between solstices. This result suggests the existence among the Iberians of rituals associated with seasonality, agrarian festivities of fecundity similar to other well-known ones of the ancient Mediterranean. The earliest chronology of the sanctuaries related to the equinoxes indicates that they became operational around mid-IV BCE, coincident with a period of major ideological changes in the Iberian society and increased Punic influence in the area. The analysis of the results suggests a possible influence of Greco-Punic beliefs on the astronomical aspects of Iberian ritual. [ABSTRACT FROM AUTHOR]

We present archaeoastronomical results of an interdisciplinary project to study Bronze Age sites of the socalled Cultura de las Motillas in the Spanish region of La Mancha. We find that winter solstice sunrise was of special importance in the funerary - and perhaps religious - practises of these peoples. The impressive megalithic monumental complex of Castillejo del Bonete shows a remarkable marker of the winter solstice sunrise on the most peculiar mountain of its horizon as well as alignments with this and other singular solar events as equinox and summer solstice. There seems to be a correspondence between the orientations of some of the main architectural structures of the monument and the general arrangement of two of the main galleries of a natural cave that lies just beneath it. Markers and orientations to the winter solstice sunrise seem to be present in other nearby contemporary sites such as the necropolis of Cerro Ortega and the motilla of El Azuer. Castillejo del Bonete stands as the first evidence of a clear solar marker in a megalithic site of the Iberian Peninsula, indicating that the precise location of the monument was carefully chosen. The alignments defined by several of its structures further reinforce its astronomical symbolism. [ABSTRACT FROM AUTHOR]

We present a compilation of orientations of seven temples dedicated to the Phoenician goddess Astarte across the Mediterranean. The chronology of the earliest temple corresponds to the Early Bronze Age - temple of Baalat Gebal at Byblos, 2800 BCE - but the rest dating back to the Iron Age, from IX to IV BCE. We find that most temples follow a sun-rising or moon-rising orientation pattern but three of them show westerly orientations in the range of azimuth between 232° and 239°. These values are consistent with the orientation custom found by Esteban & Escacena (2013a, b) in a sample of Iron Age sanctuaries of the southern half of the Iberian Peninsula that show direct influence by Phoenician colonisation. One of the potential targets of these westerly orientations is the setting of Venus at its extreme southerly position. This possibility can be related to the well-known ties between the Phoenician goddess Astarte and planet Venus. [ABSTRACT FROM AUTHOR]

We present results of an archaeoastronomical study of the Iberian cave-sanctuary of La Cueva de la Lobera in Castellar (Jaén, Spain), whose foundation has been dated to the second half of the fourth century BCE. The sanctuary consists of several terraces, a cave and a rock shelter that have been artificially modified. The main axis of the cave is oriented along the east-west direction. A small niche at the innermost part of the cave is illuminated at sunset around the equinoxes through an opening located at the western edge of the cavity. We have photographically documented the evolution of the illumination pattern inside the cave, and have found that the shapes of the niche and the patch of light show the maximum coincidence at the temporal mid-point between the solstices, one or two days from the exact date of the astronomical equinox. Finally, we speculate about the similarity between the shape of the patch of light just before sunset and the side face of one of the most common kinds of votive figurines found in this and other contemporary Iberian sanctuaries, which represent schematically an aristocratic female image, which is sometimes assimilated with the image of a feminine deity. [ABSTRACT FROM AUTHOR]

In this article, I discuss the potential of two areas that have attracted the attention of almost no archaeoastronomers: Western Polynesia and Micronesia. First, I present new results on orientations of prehistoric burial mounds in Tongatapu, discussing their possible astronomical significance. And second, I give some ideas for future research of several interesting kinds of monuments, such as the earth and stone mounds in the Tongan and Samoan archipelagos and some important archaeological sites of Micronesia. Specially promising is the study of the ancient megalithic city of Nan Madol (Pohnpei), whose main urban axes may have been defined by the rising points of prominent celestial asterisms (the Southern Cross and Orion's Belt), of much importance in the so-called star "compass" used by the navigators of the Caroline Islands. [ABSTRACT FROM AUTHOR]

We use UVES spectroscopy of PB 6 to study the variation of its physical conditions as a function of position including: temperature, density, chemical composition and velocity. We present preliminary results from this work. In particular we want to find the relevance of the contribution of the wind from the central star to the chemical composition of the nebula; we find that the contamination due to the WR wind is small. [ABSTRACT FROM PUBLISHER]