New electron density diagnostic line ratios are presented for the O iv 2s22p 2—2s2p24P and S iv 3s23p 2—3s3p24P intercombination lines around 1400Å. A comparison of these with observational data for ...the symbiotic star RR Telescopii (RR Tel), obtained with the Space Telescope Imaging Spectrograph (STIS), reveals generally very good agreement between theory and observation. However the S iv2P3/2–4P1/2 transition at 1423.824Å is found to be blended with an unknown feature at 1423.774 Å. The linewidth for the latter indicates that the feature arises from a species with a large ionization potential. In addition, the S iv2P1/2–4P3/2 transition at 1398.044 Å is identified for the first time (to our knowledge) in an astrophysical source other than the Sun, and an improved wavelength of 1397.166 Å is measured for the O iv2P1/2–4P3/2 line. The O iv and S iv line ratios in a sunspot plume spectrum, obtained with the Solar Ultraviolet Measurements of the Emitted Radiation (SUMER) instrument on the Solar and Heliospheric Observatory, are found to be consistent, and remove discrepancies noted in previous comparisons of these two ions.
Aims. Infrared and optical photometric and spectroscopic observations of the symbiotic nova RR Tel are used to study the effects and properties of dust in symbiotic binaries containing a cool Mira ...component, as well as showing "obscuration events" of increased absorption, which are typical for such Miras. Methods. A set of photometric observations of the symbiotic nova RR Tel in different wavelength bands - visual from 1949 to 2002 and near-infrared (JHKL) from 1975 to 2002 - are presented. The variability due to the normal Mira pulsation was removed from the JHKL data, which were then compared with the American Association of Variable Star Observers' (AAVSO) visual light curve. The changes of the Fe II emission line fluxes during the 1996-2000 obscuration episode were studied in the optical spectra taken with the Anglo-Australian telescope. Results. We discuss the three periods during which the Mira component was heavily obscured by dust as observed in the different wavelength bands. A change in the correlations of J with other infrared magnitudes was observed with the colour becoming redder after JD 2 446 600. Generally, J-K was comparable, while K-L was larger than typical values for single Miras. A distance estimate of 2.5 kpc, based on the IR data, is given. A larger flux decrease for the permitted than for the forbidden Fe II lines, during the obscuration episode studied, has been found. There is no evidence for other correlations with line properties, in particular with wavelength, which suggests obscuration due to separate optically thick clouds in the outer layers. Conclusions.
SuWt 2 is a planetary nebula (PN) consisting of an edge-on thin bright ionized ring, and perpendicular fainter bipolar lobes. The central star (12th magnitude) is an eclipsing binary, which is ...however too cool to ionize the PN; IUE spectra show no evidence for a hot, evolved PN central star, that could have first created and then ionised the nebula. We followed the central binary of SuWt 2 (NSV 19992) for over a decade with photometry and spectroscopy, and from these data obtained light and radial velocity curves and built an SED, from all of which we measured the stellar and system parameters. The two components are nearly identical A1 V stars, each of mass ∼2.7 M⊙. Both are in the short-lived “blue-hook” evolutionary phase that occurs between the main sequence and the Hertzsprung gap, with an age of about 520 Myr. One puzzle is that the stars' rotational velocities are different from each other, and considerably slower than synchronous with the orbital period. We find that it is possible that the center-of-mass velocity of the eclipsing pair is varying with time, suggesting that there is an unseen third orbiting body in the system.
Powerful radio galaxies and radio-loud quasars at high redshifts are frequently associated with extended emission-line regions (EELRs). Here we investigate the $\ion{O}{ii}$ EELR around the quasar ...3C 196 at $z=0.871$ using integral field spectroscopy. We also detect extended $\ion{Ne}{ii}$ emission at a distance of about 30 kpc from the core. The emission is aligned with the radio hot spots and shows a redshifted and a blueshifted component with a velocity difference of ~800 km s-1. The alignment effect and large velocities support the hypothesis that the EELR is caused by a jet-cloud interaction, which is furthermore indicated by the presence of a pronounced bend in the radio emission at the location of the radio hot spots. We also report observations of two other systems which do not show as clear indications of interactions. We find a weaker alignment of an $\ion{O}{ii}$ EELR from the $z=0.927$ quasar 3C 336, while no EELR is found around the core-dominated quasar OI 363 at $z=0.63$.
PACS (Poglitsch et al. 2) was a photometer and integral field spectrograph (IFS) operating in the FIR (50–220 μm), aboard the ESA-NASA Herschel Space Observatory (Pilbrat et al. 1). It was the first ...IFS ever on a space telescope. Herschel operated from May 2009 until April 2013, when its coolant ran out and after which it was sent off in a wide orbit around the sun. In this poster we discuss the importance of the spatial sampling of the PACS beam.
Aims
. Over the past decades, libraries of stellar spectra have been used in a large variety of science cases, including as sources of reference spectra for a given object or a given spectral type. ...Despite the existence of large libraries and the increasing number of projects of large-scale spectral surveys, there is to date only one very high-resolution spectral library offering spectra from a few hundred objects from the southern hemisphere (UVES-POP). We aim to extend the sample, offering a finer coverage of effective temperatures and surface gravity with a uniform collection of spectra obtained in the northern hemisphere.
Methods
. Between 2010 and 2020, we acquired several thousand echelle spectra of bright stars with the Mercator-HERMES spectrograph located in the Roque de Los Muchachos Observatory in La Palma, whose pipeline offers high-quality data reduction products. We have also developed methods to correct for the instrumental response in order to approach the true shape of the spectral continuum. Additionally, we have devised a normalisation process to provide a homogeneous normalisation of the full spectral range for most of the objects.
Results
. We present a new spectral library consisting of 3256 spectra covering 2043 stars. It combines high signal-to-noise and high spectral resolution over the entire range of effective temperatures and luminosity classes. The spectra are presented in four versions: raw, corrected from the instrumental response, with and without correction from the atmospheric molecular absorption, and normalised (including the telluric correction).
Marine hard-bottom communities are undergoing severe change under the influence of multiple drivers, notably climate change, extraction of natural resources, pollution and eutrophication, habitat ...degradation, and invasive species. Monitoring marine biodiversity in such habitats is, however, challenging as it typically involves expensive, non-standardized, and often destructive sampling methods that limit its scalability. Differences in monitoring approaches furthermore hinders inter-comparison among monitoring programs. Here, we announce a Marine Biodiversity Observation Network (MBON) consisting of Autonomous Reef Monitoring Structures (ARMS) with the aim to assess the status and changes in benthic fauna with genomic-based methods, notably DNA metabarcoding, in combination with image-based identifications. This article presents the results of a 30-month pilot phase in which we established an operational and geographically expansive ARMS-MBON. The network currently consists of 20 observatories distributed across European coastal waters and the polar regions, in which 134 ARMS have been deployed to date. Sampling takes place annually, either as short-term deployments during the summer or as long-term deployments starting in spring. The pilot phase was used to establish a common set of standards for field sampling, genetic analysis, data management, and legal compliance, which are presented here. We also tested the potential of ARMS for combining genetic and image-based identification methods in comparative studies of benthic diversity, as well as for detecting non-indigenous species. Results show that ARMS are suitable for monitoring hard-bottom environments as they provide genetic data that can be continuously enriched, re-analyzed, and integrated with conventional data to document benthic community composition and detect non-indigenous species. Finally, we provide guidelines to expand the network and present a sustainability plan as part of the European Marine Biological Resource Centre (
www.embrc.eu
).
Marine ecosystems, ranging from coastal seas and wetlands to the open ocean, accommodate a wealth of biological diversity from small microorganisms to large mammals. This biodiversity and its ...associated ecosystem function occurs across complex spatial and temporal scales and is not yet fully understood. Given the wide range of external pressures on the marine environment, this knowledge is crucial for enabling effective conservation measures and defining the limits of sustainable use. The development and application of omics-based approaches to biodiversity research has helped overcome hurdles, such as allowing the previously hidden community of microbial life to be identified, thereby enabling a holistic view of an entire ecosystem’s biodiversity and functioning. The potential of omics-based approaches for marine ecosystems observation is enormous and their added value to ecosystem monitoring, management, and conservation is widely acknowledged. Despite these encouraging prospects, most omics-based studies are short-termed and typically cover only small spatial scales which therefore fail to include the full spatio-temporal complexity and dynamics of the system. To date, few attempts have been made to establish standardised, coordinated, broad scaled, and long-term omics observation networks. Here we outline the creation of an omics-based marine observation network at the European scale, the European Marine Omics Biodiversity Observation Network (EMO BON). We illustrate how linking multiple existing individual observation efforts increases the observational power in large-scale assessments of status and change in biodiversity in the oceans. Such large-scale observation efforts have the added value of cross-border cooperation, are characterised by shared costs through economies of scale, and produce structured, comparable data. The key components required to compile reference environmental datasets and how these should be linked are major challenges that we address.
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