scholarly journals Detection of new eruptions in the Magellanic Clouds luminous blue variables R 40 and R 110

2018 ◽  
Vol 613 ◽  
pp. A33 ◽  
Author(s):  
J. C. N. Campagnolo ◽  
M. Borges Fernandes ◽  
N. A. Drake ◽  
M. Kraus ◽  
C. A. Guerrero ◽  
...  
Keyword(s):  
Magellanic Clouds ◽  
The Other ◽  
Photometric Analysis ◽  
Spectral Modeling ◽  
Luminous Blue Variables ◽  
Quiescent Phase ◽  
Type Spectrum ◽  
Probable Presence ◽  
Process Elements ◽  
Circumstellar Environment

We performed a spectroscopic and photometric analysis to study new eruptions in two luminous blue variables (LBVs) in the Magellanic Clouds. We detected a strong new eruption in the LBV R40 that reached V ~ 9.2 in 2016, which is around 1.3 mag brighter than the minimum registered in 1985. During this new eruption, the star changed from an A-type to a late F-type spectrum. Based on photometric and spectroscopic empirical calibrations and synthetic spectral modeling, we determine that R 40 reached Teff = 5800–6300 K during this new eruption. This object is thereby probably one of the coolest identified LBVs. We could also identify an enrichment of nitrogen and r- and s-process elements. We detected a weak eruption in the LBV R 110 with a maximum of V ~ 9.9 mag in 2011, that is, around 1.0 mag brighter than in the quiescent phase. On the other hand, this new eruption is about 0.2 mag fainter than the first eruption detected in 1990, but the temperature did not decrease below 8500 K. Spitzer spectra show indications of cool dust in the circumstellar environment of both stars, but no hot or warm dust was present, except by the probable presence of PAHs in R 110. We also discuss a possible post-red supergiant nature for both stars.

29. Stellar Spectra (Spectres Stellaires)

1991 ◽  
Vol 21 (1) ◽  
pp. 309-326
Keyword(s):  
Milky Way ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Dynamical Interaction ◽  
Stellar Spectra ◽  
Luminous Blue Variables ◽  
Classical Novae ◽  
Giant Stars ◽  
Red Giant ◽  
Sydney Australia

In the triennium under review, from the late second half of 1987 to the early second half of 1990, Commission 29 has sponsored or cosponsored the following IAU Conferences: Coll. No. 106, “Evolution of Peculiar Red Giant Stars,” Bloomington, Indiana, July 1988; CoU. No. 114, “White Dwarfs,” Hanover, New Hamsphire, August 1988; Coll. No. 113, “Physics of Luminous Blue Variables,” Val Morin, Quebec, August 1988; Coll. No. 122, “Physics of Classical Novae,” Madrid, Spain, June 1989; Symp. No. 143, “Wolf-Rayet Stars and Interrelations with Other Massive Stars in Galaxies,” Denpasar, Indonesia, June 1990; Symp. No 148, “The Magellanic Clouds and their Dynamical Interaction with the Milky Way,” Sydney, Australia, July 1990; Symp. No. 145, “Evolution of Stars: the Photospheric Abundance Connection,” Druzba, Bulgaria. August 1990.

XIV.—On Analysing the Physical Evolution of Galaxies

1960 ◽  
Vol 65 (3) ◽  
pp. 207-222
Author(s):  
V. C. Reddish
Keyword(s):  
Magellanic Clouds ◽  
The Other ◽  
Bright Star ◽  
Evolution Of Galaxies ◽  
Other Hand ◽  
Luminosity Functions ◽  
Mass Ratios ◽  
Set Up

SYNOPSISInvestigations based on gas masses, bright star counts, and luminosity-mass ratios of galaxies lead to one of two conclusions. If the galaxies are all of the same age, the faint ends of the initial luminosity functions of stars at formation differ greatly from one galaxy to another. On the other hand consistent results in the analysis are obtained with luminosity functions that are more nearly constant and ages which range from one to thirty thousand-million years. The various possibilities can be tested by observations on the Magellanic Clouds.Equations are set up which describe, as functions of time, the integrated properties of a galaxy as a system of stars and gas.

scholarly journals The multipopulation phenomenon in Galactic globular clusters: M4 and M22

2009 ◽  
Vol 5 (S266) ◽  
pp. 326-332
Author(s):  
S. Villanova ◽  
G. Piotto ◽  
A. F. Marino ◽  
A. P. Milone ◽  
A. Bellini ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectroscopic Data ◽  
Globular Clusters ◽  
Stellar Population ◽  
The Other ◽  
Wide Field ◽  
Galactic Globular Clusters ◽  
Red Giant ◽  
Process Elements ◽  
Different Characteristics

AbstractWe present an abundance analysis based on high-resolution spectra of red-giant-branch (RGB) stars in the Galactic globular clusters NGC 6121 (M4) and NGC 6656 (M22). Our aim was to study their stellar population in the context of the multipopulation phenomenon recently discovered to affect some globular clusters. Analysis was performed for the following elements: O, Na, Mg, Al, Ca, Fe, Y, and Ba. Spectroscopic data were completed by high-precision wide-field U BV IC ground-based photometry and HST/ACS observations. For M4, we find a well-defined Na–O anticorrelation composed of two distinct groups of stars with significantly different Na and O content. The two groups of Na-rich and Na-poor stars populate two different regions along the RGB. As regards M22, Na and O follow the well-known anticorrelation found in many other GCs. However, at odds with M4, it appears to be continuous without any hint of clumpiness. On the other hand, we identified two clearly separated groups of stars with significantly different abundances of the s-process elements Y, Zr and Ba. The relative numbers of the members of both groups are very similar to the ratio of the stars in the two subgiant branches of M22 recently found by Piotto (2009). The s-element-rich stars are also richer in iron and have higher Ca abundances. This makes M22 the second cluster after ω Centauri where an intrinsic spread in Fe was found. Both spectroscopic and photometric results imply the presence of two stellar populations in M4 and M22, even if both clusters have completely different characteristics.

scholarly journals Multiperspective simulations for implementing a change in service: stroke telethrombolysis

2021 ◽  
pp. bmjstel-2020-000848
Author(s):  
Craig William Brown ◽  
Petrus Elofuke
Keyword(s):  
Patient Care ◽  
Service Providers ◽  
Stroke Care ◽  
Referral Hospital ◽  
The Other ◽  
Treatment Delivery ◽  
Hyperacute Stroke ◽  
Simulation Based ◽  
Change In Practice ◽  
Process Elements

Simulation-based training has been used in a variety of ways to demonstrate and improve process elements of patient care. One example of this is in improving door-to-needle times in hyperacute stroke care. Changes in service by one team which affect another bring difference of opinions between service providers involved and can lead to interdepartmental conflict. In this report, we use Kurt Lewin’s model for change to describe how a series of multiperspective simulation-based exercises were used in implementing a change in practice with the introduction of telethrombolysis within a large tertiary stroke referral hospital. The use of multiperspective or bidirectional simulation allowed a ‘meeting of minds’ with each service able to illustrate key themes to the other service. This was demonstrated through a series of simulation-based exercises. Following successful simulation-based exercises and subsequent interdepartmental agreement, a telethrombolysis pilot has been conducted within our centre. Ongoing audit of practice continues as this method of treatment delivery is continued. Further simulation work is planned as a national thrombectomy service is instigated.

scholarly journals Australian Journal of Physics Astrophysical Supplement

1976 ◽  
Vol 29 (5) ◽  
pp. 471
Author(s):  
JN Clarke ◽  
AG Little ◽  
BY Mills
Keyword(s):  
Flux Density ◽  
High Frequency ◽  
Magellanic Clouds ◽  
Australian Journal ◽  
The Other ◽  
Optical Data ◽  
Radio Sources ◽  
Angular Extent

The fourth catalogue of radio sources observed at 408 MHz with the Molonglo radiotelescope is presented. A total of 1349 sources is listed to a limiting flux density of 0�2 Jy, the catalogue being largely complete above 0� 25 Jy. The area of sky surveyed includes the Magellanic Clouds as well as a comparison region of similar angular extent. Detailed notes are provided on some of the Cloud sources, and maps are given for complex sources in the region of the Clouds. Those sources for which high-frequency or optical data are available are classified into two lists, one of Cloud members and the other of 'unidentified nonthermal sources', presumably not Cloud members.

scholarly journals The age-metallicity relation in the thin disk

2008 ◽  
Vol 4 (S252) ◽  
pp. 265-266
Author(s):  
Ji Li ◽  
Bo Liang ◽  
Weishi Fan
Keyword(s):  
Thin Disk ◽  
The Other ◽  
Photometric Analysis

AbstractWith two stellar sample A and B, the age-metallicity relation (AMR) in the Galactic thin disk is investigated. The results show two different AMRs: one is a nearly flat AMR from photometric analysis of sample A, the other is an obvious AMR derived from spectroscoipic analysis of sample B.

Radiometric dating of the Coldbrook Group of southern New Brunswick, Canada

1969 ◽  
Vol 6 (3) ◽  
pp. 393-398 ◽  
Author(s):  
R. F. Cormier
Keyword(s):  
New Brunswick ◽  
Lower Cambrian ◽  
Volcanic Rocks ◽  
The Other ◽  
Radiometric Dating ◽  
Late Devonian ◽  
Initial Ratio ◽  
Initial Value ◽  
Saint John ◽  
Probable Presence

The Coldbrook Group of southern New Brunswick is composed almost entirely of volcanic rocks and has been assigned a Precambrian age on the basis of field relationships. Rocks of the group are overlain by fossiliferous Lower Cambrian beds of the Saint John Group.Rubidium-strontium total-rock analyses of 46 samples of Coldbrook Group volcanic rocks have been carried out. Analysis of the data indicates the probable presence of two different isochron ages. One of these is apparently defined by those rocks in which the ratio 87Rb/86Sr is low, with values less than about 1.0. This isochron yields an age of 750 ± 80 million years, with an initial ratio 87Sr/86Sr of 0.7054 ± 0.0010. The other isochron is defined by rocks in which the value of the ratio 87Rb/86Sr is higher, with values greater than about 1.0. The age calculated from the second isochron is 370 ± 38 million years, with an indicated initial value for the ratio 87Sr/86Sr of 0.7135 ± 0.0010.The 750 million year age is interpreted to represent the time of extrusion of the Coldbrook volcanics. The 370 million year age appears to be secondary and related to metamorphism of the Coldbrook Group. This age is correlated with the Acadian orogeny, which strongly deformed this part of the northern Appalachians in Middle to Late Devonian time.

scholarly journals Microlensing: A Tool to Probe Distant Binary Populations

2001 ◽  
Vol 200 ◽  
pp. 529-538 ◽  
Author(s):  
Rosanne Di Stefano
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Stellar Population ◽  
Planetary Systems ◽  
Magellanic Clouds ◽  
The Other ◽  
Distant Star ◽  
Large Numbers ◽  
External Galaxies ◽  
Statistical Studies

Programs designed to observe gravitational microlensing are poised to provide a great deal of information about binary populations far from Earth, including those in the Galactic Bulge, in the Magellanic Clouds, in M31, and perhaps in other external galaxies. Because many millions of stars are monitored, microlensing observations allow us to study binaries in three ways: (1) when they are “involved” in a microlensing event (as either a lens or lensed source), (2) when variability due to binarity produces significant variations in the light curve, and (3) when light from a more distant star is attenuated or refracted by matter associated with the binary system (e.g., in a disk).Microlensing observations will discover large numbers of binaries and planetary systems in a variety of galactic environments. Thus, comparative statistical studies of binary properties (distributions of mass ratios and orbital separations) are possible.An intriguing sign that we have already begun to learn about binaries through microlensing observations comes from work indicating that all of the lenses detected to date may in fact be binaries. For observations along the direction of the Magellanic Clouds this would imply that, if the lenses are primarily located in the Halo, then MACHOs tend to be binaries. If, on the other hand, most of the lenses are located in the Magellanic Clouds, microlensing observations are giving us a unique way to explore a distant stellar population of binaries.

scholarly journals Infrared properties of active OB stars in the Magellanic Clouds from the Spitzer SAGE survey

2010 ◽  
Vol 6 (S272) ◽  
pp. 254-259
Author(s):  
Alceste Z. Bonanos ◽  
Danny J. Lennon ◽  
Derck L. Massa ◽  
Marta Sewilo ◽  
Fabian Köhlinger ◽  
...  
Keyword(s):  
Magellanic Clouds ◽  
Spectral Energy ◽  
Be Stars ◽  
Energy Distributions ◽  
Photometric Variability ◽  
B Stars ◽  
Ob Stars ◽  
Luminous Blue Variables ◽  
Red Supergiants ◽  
Be Star

AbstractWe present a study of the infrared properties of 4922 spectroscopically confirmed massive stars in the Large and Small Magellanic Clouds, focusing on the active OB star population. Besides OB stars, our sample includes yellow and red supergiants, Wolf-Rayet stars, Luminous Blue Variables (LBVs) and supergiant B[e] stars. We detect a distinct Be star sequence, displaced to the red, and find a higher fraction of Oe and Be stars among O and early-B stars in the SMC, respectively, when compared to the LMC, and that the SMC Be stars occur at higher luminosities. We also find photometric variability among the active OB population and evidence for transitions of Be stars to B stars and vice versa. We furthermore confirm the presence of dust around all the supergiant B[e] stars in our sample, finding the shape of their spectral energy distributions (SEDs) to be very similar, in contrast to the variety of SED shapes among the spectrally variable LBVs.

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