Ring Nebulae Abundances: Probes of the Evolutionary History of Luminous Blue Variable Stars

1999 ◽  
Vol 169 ◽  
pp. 400-404
Author(s):  
Linda J. Smith ◽  
Antonella Nota ◽  
Anna Pasquali ◽  
Claus Leitherer ◽  
Mark Clampin ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Hubble Space Telescope ◽  
Variable Stars ◽  
Surface Layers ◽  
The Past ◽  
Faint Object ◽  
History Of ◽  
Faint Object Spectrograph ◽  
Ring Nebulae ◽  
Luminous Blue Variable

The ring nebulae that surround most Luminous Blue Variable (LBV) stars are believed to be the relics of one or more giant eruptions (cf. Nota, these proc.). The nebulae thus represent the stellar surface layers at the time of the eruption(s) and by analysing their chemical composition and dynamics, it is possible to infer the past evolutionary state of the star.Observations with the Hubble Space Telescope (HST) and the Faint Object Spectrograph (FOS) were obtained for the nebulae around the two LMC LBVs R127 and R143, and the Ofpe/WN9 star S119 for the purpose of obtaining abundances. The spectra cover the wavelength range 3235–6818 Å and aslit of dimensions 1″.7 × 0″.2 was placed on the brightest portion of each nebula. Full details of these observations are given in Smith et al. (1998).

scholarly journals Extensive introgression and mosaic genomes of Mediterranean endemic lizards

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Weizhao Yang ◽  
Nathalie Feiner ◽  
Catarina Pinho ◽  
Geoffrey M. While ◽  
Antigoni Kaliontzopoulou ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Mediterranean Islands ◽  
The Past ◽  
Island Endemics ◽  
Extant Species ◽  
Mediterranean Island ◽  
History Of ◽  
Entire History ◽  
The Mediterranean ◽  
The Mediterranean Basin

AbstractThe Mediterranean basin is a hotspot of biodiversity, fuelled by climatic oscillation and geological change over the past 20 million years. Wall lizards of the genus Podarcis are among the most abundant, diverse, and conspicuous Mediterranean fauna. Here, we unravel the remarkably entangled evolutionary history of wall lizards by sequencing genomes of 34 major lineages covering 26 species. We demonstrate an early (>11 MYA) separation into two clades centred on the Iberian and Balkan Peninsulas, and two clades of Mediterranean island endemics. Diversification within these clades was pronounced between 6.5–4.0 MYA, a period spanning the Messinian Salinity Crisis, during which the Mediterranean Sea nearly dried up before rapidly refilling. However, genetic exchange between lineages has been a pervasive feature throughout the entire history of wall lizards. This has resulted in a highly reticulated pattern of evolution across the group, characterised by mosaic genomes with major contributions from two or more parental taxa. These hybrid lineages gave rise to several of the extant species that are endemic to Mediterranean islands. The mosaic genomes of island endemics may have promoted their extraordinary adaptability and striking diversity in body size, shape and colouration, which have puzzled biologists for centuries.

scholarly journals HST FOS Observations of KPD0005+5106: A Subluminous WN-WC Descendant by Ongoing Mass Outflow?

1993 ◽  
Vol 155 ◽  
pp. 498-498
Author(s):  
Edward M. Sion ◽  
Ronald A. Downes
Keyword(s):  
Hubble Space Telescope ◽  
Absorption Lines ◽  
High Excitation ◽  
Strong Emission ◽  
Present Evidence ◽  
High Ionization ◽  
Faint Object ◽  
Mass Outflow ◽  
Line Widths ◽  
Faint Object Spectrograph

We report the results of spectroscopic observations of the ultra-high excitation, helium-rich, pre-white dwarf KPD0005+5106 obtained with the Hubble Space Telescope Faint Object Spectrograph (FOS) in 1991 May and July with the red (FOS/RD) and blue (FOS/BL) Digicon detectors. The data reveal a rich line spectrum both in absorption and in emission with ultra-high excitation species present including O VIII, N V, possibly C V, Fe VI, Fe VII and numerous weaker high n, low l, transitions of C IV and O VI as well as the predominant He II (3 → n) and He II (Balmer α) absorption lines. There is a strong emission complex at 2981A which we identify primarily as three transitions of N V commonly seen in WN Wolf-Rayet spectra. We present evidence that high ionization species in emission (O VIII, N V, C IV, Si IV) and in absorption (He II, Fe VI, Fe VII) are longward-shifted relative to the far UV resonance (circumstellar) absorption lines by 25–50 km/s. Based upon the detected species, line velocities, line widths and emission features, we conclude that (1) KPD0005 is the very likely the evolutionary descendant of a WN-WC subluminous Wolf-Rayet progenitor and (2) has ongoing, possibly episodic, mass outflow.

scholarly journals Preliminary analysis of a Hubble FOS spectrum of VW Hyi in quiescence: A DAZQ white dwarf and accretion belt/ring

1996 ◽  
Vol 158 ◽  
pp. 249-250
Author(s):  
E. M. Sion ◽  
M. Huang ◽  
F. H. Cheng ◽  
I. Hubeny ◽  
P. Szkody
Keyword(s):  
White Dwarf ◽  
Preliminary Analysis ◽  
Hubble Space Telescope ◽  
Uv Spectrum ◽  
Space Telescope ◽  
Dwarf Nova ◽  
Faint Object ◽  
Faint Object Spectrograph

AbstractWe present a preliminary analysis of the UV spectrum of the dwarf nova VW Hyi during early quiescence, obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST). The data were obtained approximately one day after the end of a normal outburst.

scholarly journals The past, present and future of ancient bacterial DNA

2020 ◽  
Vol 6 (7) ◽  
Author(s):  
Nicolas Arning ◽  
Daniel J. Wilson
Keyword(s):  
Demographic Transition ◽  
Dental Plaque ◽  
Evolutionary History ◽  
High Throughput Sequencing ◽  
Industrial Revolution ◽  
Environmental Isolates ◽  
Bacterial Dna ◽  
Content Type ◽  
The Past ◽  
History Of

Groundbreaking studies conducted in the mid-1980s demonstrated the possibility of sequencing ancient DNA (aDNA), which has allowed us to answer fundamental questions about the human past. Microbiologists were thus given a powerful tool to glimpse directly into inscrutable bacterial history, hitherto inaccessible due to a poor fossil record. Initially plagued by concerns regarding contamination, the field has grown alongside technical progress, with the advent of high-throughput sequencing being a breakthrough in sequence output and authentication. Albeit burdened with challenges unique to the analysis of bacteria, a growing number of viable sources for aDNA has opened multiple avenues of microbial research. Ancient pathogens have been extracted from bones, dental pulp, mummies and historical medical specimens and have answered focal historical questions such as identifying the aetiological agent of the black death as Yersinia pestis . Furthermore, ancient human microbiomes from fossilized faeces, mummies and dental plaque have shown shifts in human commensals through the Neolithic demographic transition and industrial revolution, whereas environmental isolates stemming from permafrost samples have revealed signs of ancient antimicrobial resistance. Culminating in an ever-growing repertoire of ancient genomes, the quickly expanding body of bacterial aDNA studies has also enabled comparisons of ancient genomes to their extant counterparts, illuminating the evolutionary history of bacteria. In this review we summarize the present avenues of research and contextualize them in the past of the field whilst also pointing towards questions still to be answered.

scholarly journals A 21 Centimeter Absorber Identified with a Spiral Galaxy: Hubble Space Telescope Faint Object Spectrograph and Wide-Field Camera Observations of 3CR 196

1996 ◽  
Vol 456 ◽  
pp. 132 ◽  
Author(s):  
Ross D. Cohen ◽  
E. A. Beaver ◽  
Athanassios Diplas ◽  
Vesa T. Junkkarinen ◽  
Thomas A. Barlow ◽  
...  
Keyword(s):  
Spiral Galaxy ◽  
Hubble Space Telescope ◽  
Wide Field ◽  
Space Telescope ◽  
Faint Object ◽  
Faint Object Spectrograph

The Measure of the Machine: How Exposure to Current Technology Can Upgrade a Student’s Education

2004 ◽  
Author(s):  
Robert Conger ◽  
Amanda Blum ◽  
Paul A. Erickson
Keyword(s):  
Computer Technology ◽  
Evolutionary History ◽  
The Internet ◽  
Technology In Education ◽  
Computing Power ◽  
Educational Benefits ◽  
The Past ◽  
History Of ◽  
Design Projects ◽  
Remarkable Progress

Over the past decade there has been a distinct trend toward implementing computer technology in education. The advent of affordable, student accessible computing power has allowed engineering curricula to follow the trends of computer technology in the engineering workplace. The developments in hardware and software, combined with the explosive entrance of the Internet, have allowed design projects to evolve into elaborate and imaginative endeavors. The enhanced speed at which projects can now be completed allows students the opportunity to undertake tasks of greater magnitude, while the advanced tools now available permit students to solve more sophisticated and lifelike problems. The examination of a senior-level design course, in which students must design and build a maze-solving robot, serves to highlight the educational benefits that stand to be gained through the judicious application of technology. The evolutionary history of this design course demonstrates the remarkable progress that computer technology has allowed in educational settings.

scholarly journals Power, competition, and the nature of history

Paleobiology ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 517-530 ◽  
Author(s):  
Geerat J. Vermeij
Keyword(s):  
High Frequency ◽  
Evolutionary History ◽  
Metabolic Evolution ◽  
Competition And Cooperation ◽  
The Past ◽  
Directional Change ◽  
History Of ◽  
Repeated Evolution ◽  
Ecosystem Level

AbstractHistorians have debated whether pathways and events from the past to the present are influenced largely by contingency, the dependence of outcomes on particular prior conditions, or whether there is long-term emergent directional change. Previous arguments for predictability in evolutionary history relied on the high frequency of convergence, but the repeated evolution of widely favored adaptations need not imply long-term directionality. Using evidence from the fossil record and arguments concerning the metabolic evolution of organisms, I show here that power (total energy taken up and expended per unit time) has increased stepwise over time at ecosystem-level and global scales thanks to the ratchet-like, cumulative effects of competition and cooperation and to the disproportionate influence of powerful top competitors and opportunistic species on emergent ecosystem properties and processes. The history of life therefore exhibits emergent directionality at large ecosystem-wide scales toward greater power.

Sign in / Sign up

Export Citation Format

Share Document