scholarly journals Exceptionally fast ejecta seen in light echoes of Eta Carinae’s Great Eruption

2018 ◽  
Vol 480 (2) ◽  
pp. 1457-1465 ◽  
Author(s):  
Nathan Smith ◽  
Armin Rest ◽  
Jennifer E Andrews ◽  
Tom Matheson ◽  
Federica B Bianco ◽  
...  
Keyword(s):  
Light Echoes

Light echoes - Novae

1988 ◽  
Vol 327 ◽  
pp. 347 ◽  
Author(s):  
Bradley E. Schaefer
Keyword(s):  
Light Echoes

Light echoes - Type II supernovae

1987 ◽  
Vol 323 ◽  
pp. L51 ◽  
Author(s):  
Bradley E. Schaefer
Keyword(s):  
Type Ii ◽  
Light Echoes

scholarly journals Optical Coherence Tomography in Multiple Sclerosis

2019 ◽  
Vol 39 (06) ◽  
pp. 711-717 ◽  
Author(s):  
Jennifer S. Graves
Keyword(s):  
Multiple Sclerosis ◽  
Optical Coherence Tomography ◽  
Demyelinating Disease ◽  
Ganglion Cells ◽  
Neuronal Loss ◽  
Clinical Effects ◽  
Optical Coherence ◽  
Two Dimensional Image ◽  
Light Echoes ◽  
Afferent Visual System

AbstractOptical coherence tomography (OCT) grew out of a convergence of rapid advancements in femtoseconds optics research and fiber optic commercial technology. The basic concept of OCT is to “see” into tissues using light echoes, analogous to the sound echoes of ultrasonography. Multiple A-scans are assembled into a B-scan two-dimensional image of the tissue of interest. Retina is an ideal tissue for evaluation by OCT, since the eye is designed to minimize light scattering through the anterior chamber and vitreous. OCT has had a significant impact on the field of multiple sclerosis, where it has allowed direct imaging of the myelin-free segments of axons and cell bodies of retinal ganglion cells. Together with precise functional measurements of the afferent visual system, the addition of robust structural measurements of retinal injury has allowed for an unprecedented ability to correlate clinical effects with the degree of neuronal loss. In addition, OCT has proven helpful to distinguish different forms of demyelinating disease, such as multiple sclerosis (MS) and neuromyelitis optica, and has provided ideal outcome measures in remyelination and neuroprotection trials.

scholarly journals Light echoes from the plateau in Eta Carinae’s Great Eruption reveal a two-stage shock-powered event

2018 ◽  
Vol 480 (2) ◽  
pp. 1466-1498 ◽  
Author(s):  
Nathan Smith ◽  
Jennifer E Andrews ◽  
Armin Rest ◽  
Federica B Bianco ◽  
Jose L Prieto ◽  
...  
Keyword(s):  
Direct Evidence ◽  
Binary Interaction ◽  
Shock Interaction ◽  
Spectral Evolution ◽  
Two Stage ◽  
Circumstellar Material ◽  
Broad Emission ◽  
Wide Range ◽  
Light Echoes ◽  
Η Car

ABSTRACT We present multi-epoch photometry and spectroscopy of a light echo from η Carinae’s 19th century Great Eruption. This echo's light curve shows a steady decline over a decade, sampling the 1850s plateau of the eruption. Spectra show the bulk outflow speed increasing from ∼150 km s−1 at early times, up to ∼600 km s−1 in the plateau. Later phases also develop remarkably broad emission wings indicating mass accelerated to more than  10 000 km s−1. Together with other clues, this provides direct evidence for an explosive ejection. This is accompanied by a transition from a narrow absorption line spectrum to emission lines, often with broad or asymmetric P Cygni profiles. These changes imply that the pre-1845 luminosity spikes are distinct from the 1850s plateau. The key reason for this change may be that shock interaction with circumstellar material (CSM) dominates the plateau. The spectral evolution of η Car closely resembles that of the decade-long eruption of UGC 2773-OT, which had clear signatures of shock interaction. We propose a two-stage scenario for η Car’s eruption: (1) a slow outflow in the decades before the eruption, probably driven by binary interaction that produced a dense equatorial outflow, followed by (2) explosive energy injection that drove CSM interaction, powering the plateau and sweeping slower CSM into a fast shell that became the Homunculus. We discuss how this sequence could arise from a stellar merger in a triple system, leaving behind the eccentric binary seen today. This gives a self-consistent scenario that may explain interacting transients across a wide range of initial mass.

scholarly journals Light Echoes of Transients and Variables in the Local Universe

2012 ◽  
Vol 29 (4) ◽  
pp. 466-481 ◽  
Author(s):  
A. Rest ◽  
B. Sinnott ◽  
D. L. Welch
Keyword(s):  
Interstellar Dust ◽  
Three Dimensional ◽  
Large Magellanic Cloud ◽  
Multiple Perspectives ◽  
Local Universe ◽  
New Developments ◽  
Light Echoes ◽  
Dimensional Distribution ◽  
History Of ◽  
The Many

AbstractAstronomical light echoes, the time-dependent light scattered by dust in the vicinity of varying objects, have been recognized for over a century. Initially, their utility was thought to be confined to mapping out the three-dimensional distribution of interstellar dust. Recently, the discovery of spectroscopically useful light echoes around centuries-old supernovae in the Milky Way and the Large Magellanic Cloud has opened up new scientific opportunities to exploit light echoes.In this review, we describe the history of light echoes in the local Universe and cover the many new developments in both the observation of light echoes and the interpretation of the light scattered from them. Among other benefits, we highlight our new ability to classify outbursting objects spectroscopically, view them from multiple perspectives, obtain a spectroscopic time series of the outburst, and establish accurate distances to the source event. We also describe the broader range of variable objects with properties that may be better understood from light-echo observations. Finally, we discuss the prospects of new light-echo techniques not yet realized in practice.

scholarly journals THE RECURRENT NOVA T Pyx: DISTANCE AND REMNANT GEOMETRY FROM LIGHT ECHOES

2013 ◽  
Vol 770 (2) ◽  
pp. L33 ◽  
Author(s):  
J. L. Sokoloski ◽  
Arlin P. S. Crotts ◽  
Stephen Lawrence ◽  
Helena Uthas
Keyword(s):  
Light Echoes ◽  
Recurrent Nova
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