Uncertainties in the solar photospheric oxygen abundance

The purpose of this work is to better understand the confidence limits of the photospheric solar oxygen abundance derived from three-dimensional models using the forbidden [OI] line at 6300 \AA , including correlations with other parameters involved. We worked with a three-dimensional empirical model and two solar intensity atlases. We employed Bayesian inference as a tool to determine the most probable value for the solar oxygen abundance given the model chosen. We considered a number of error sources, such as uncertainties in the continuum derivation, in the wavelength calibration and in the abundance/strength of Ni. Our results shows correlations between the effects of several parameters employed in the derivation. The Bayesian analysis provides robust confidence limits taking into account all of these factors in a rigorous manner. We obtain that, given the empirical three-dimensional model and the atlas observations employed here, the most probable value for the solar oxygen abundance is $\log(\epsilon_O) = 8.86\pm0.04$. However, we note that this uncertainty does not consider possible sources of systematic errors due to the model choice.Comment: Accepted for publication in Astronomy and Astrophysic

The poorly-known amblypygid fauna (Arachnida, Amblypygi) of Honduras, Central America: an overview

A significant study of the amblypygid fauna of Honduras is lacking. Historically, species were misidentified and data on distribution, natural history and conservation status of the known species are lacking or insufficient. In this contribution, an overview on the amblypygids of Honduras, including taxonomy, distribution, natural history and comments on their conservation are provided. In a review of the literature of the Honduran amblypygids, we examined 21 works, including books, unpublished thesis, articles, the World Amblypygi Catalogue (2023), as well as the website Arácnidos de Centroamérica and the citizen-science websites Alamy, iNaturalist and Flicks. Only the family Phrynidae, with the genera Paraphrynus Moreno, 1940 and Phrynus Lamarck, 1801, is known to occur in Honduras. A total of seven species have been recorded, but only four [Paraphrynus laevifrons (Pocock, 1894), Phrynus palenque Armas, 1996, Ph. similis Armas, Víquez & Trujillo, 2017 and Ph. whitei Gervais, 1842] have been positively identified. No endemic species are known, but available data suggest that some undescribed new species may be restricted to Honduras. In order to understand the amblypygids of Honduras, sampling within the country must be conducted and revisionary studies will be needed. This paper examines our current knowledge of the fauna

Spatially resolved measurements of the solar photospheric oxygen abundance

Aims. We report the results of a novel determination of the solar oxygen abundance using spatially resolved observations and inversions. We seek to derive the photospheric solar oxygen abundance with a method that is robust against uncertainties in the model atmosphere. Methods. We use observations with spatial resolution obtained at the Vacuum Tower Telescope to derive the oxygen abundance at 40 different spatial positions in granules and intergranular lanes. We first obtain a model for each location by inverting the Fe 

Thirty Years of GOSHIP and WOCE Data: Atlantic Overturning of Mass, Heat, and Freshwater Transport

The Atlantic Meridional Overturning Circulation (AMOC) plays a vital role in global climate, redistributing heat, and freshwater. It is predicted to decline due to anthropogenic climate change, with major implications for global climate. Accurately assessing AMOC strength with in situ observations has inspired a number of dedicated observing systems in the Atlantic since the 2000s. However, no consensus has been reached on whether the slowdown of the AMOC and its associated heat and freshwater transports is occurring. These dedicated systems are too recent to detect long-term trends. We have analyzed hydrographic data from zonal sections across the Atlantic for 30 years that predate and overlap the era of AMOC observations. Our results show no changes in the AMOC for all sections analyzed over the whole Atlantic for the last 30 years. We also find an increased export of freshwater from the South Atlantic associated with an increase in upper salinity

Flows along arch filaments observed in the GRIS ‘very fast spectroscopic mode’

A new generation of solar instruments provides improved spectral, spatial, and temporal resolution, thus facilitating a better understanding of dynamic processes on the Sun. High-resolution observations often reveal multiple-component spectral line profiles, e.g., in the near-infrared He i 10830 Å triplet, which provides information about the chromospheric velocity and magnetic fine structure. We observed an emerging flux region, including two small pores and an arch filament system, on 2015 April 17 with the ‘very fast spectroscopic mode’ of the GREGOR Infrared Spectrograph (GRIS) situated at the 1.5-meter GREGOR solar telescope at Observatorio del Teide, Tenerife, Spain. We discuss this method of obtaining fast (one per minute) spectral scans of the solar surface and its potential to follow dynamic processes on the Sun. We demonstrate the performance of the ‘very fast spectroscopic mode’ by tracking chromospheric high-velocity features in the arch filament system

Gravest Empirical Mode to be used by Inverted Echo Sounders in order to determine the zonal flows in the South Atlantic

Four Pressure-equipped Inverted Echo Sounders (PIES) were deployed at about 10°W, between 19 and 35°S, the South Atlantic Gateway (SAGA), in order to determine the zonal flows in the South Atlantic. Those PIES will allow to observe the circulation of two water masses, the South Atlantic Central Water (SACW) and the North Atlantic Deep Water (NADW), that flow in opposite directions across the South Atlantic, between Cape town and Brazil, through the SAGA. The measurements from the PIES, together with historical hydrographic data, permit to estimate the profiles of temperature and salinity of the water column, and therefore the density. Besides, using the thermal-wind equation, it is possible to retrieve the geostrophic velocity from an array of PIES. In order to get those estimations of temperature and salinity, it is necessary to determine the Gravest Empirical Mode (GEM), a relationship between the acoustic travel time observed by the PIES and the historical observations of salinity and temperature in the study area. In this work, we will show the GEM estimated for the SAGA, calculated using historical hydrographic data from CTDs and Argo Float, as well as, the estimations of the error in the geostrophic transport