Delta Scorpii: el nacimiento de una estrella Be

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Las estrellas Be

El estadio Be no es sólo una etapa evolutiva en las vidas de algunas estrellas calientes de tipo B de rápida rotación sino también un fenómeno transitorio que puede ir y venir con el paso de los años en la misma estrella.  Varias razones se han propuesto para explicar el comportamiento de estas estrellas y aun están en debate.

Note on automatic rejection of low signal-to-noise data

Note on Automatic Rejection of Low Signal-to-noise Data

The AAVSO has a policy in place that states positive observations having errors equal to or greater than 1.0 magnitudes are not accepted as is. For a given measurement, an error of 1.0 magnitude is equivalent to a signal-to-noise ratio of 1, meaning that the purported signal is indistinguishable from the average noise fluctuation in the data and statistically is not a significant detection.

Alert Notice 441: Monitoring of Bright Giant Variables requested in support of ground-based spectroscopy and for long-term study

Note:  A thread for this campaign has been created in the AAVSO Campaigns and Observation Reports discussion forum:

Coverage of the stars in this campaign should be continued for long term monitoring. Spectroscopy is not being obtained, but optical coverage is needed to help understand their behavior.  -  Elizabeth O. Waagen, 17 April 2020

Alert Notice 434: Outburst of NSV 1436

March 30, 2011: The cataclysmic variable NSV 1436 has been discovered in outburst.  This is the first bright outburst of this star observed since 1948, and followup observations are strongly encouraged.  Little is known about the nature of NSV 1436, and observations may help shed light on whether the star is an infrequently outbursting normal dwarf nova, a WZ Sge star, or recurrent nova.

Archival Data Digitization -- Work In Progress

The AAVSO's volunteer-driven project to digitize paper archives of variable star observations is moving forward, and there have been some exciting developments over the past few months that deserve to be mentioned.  Here, I'll summarize some of the happenings in this project, and talk about some of the issues that have arisen at AAVSO and among the volunteers. 

Special Notice #234: Outburst of FS Aurigae

February 14, 2011: Further to AAVSO Alert Notice 428 (2010 Nov 30), the dwarf nova FS Aurigae appears to be in outburst.  The current outburst was detected simultaneously by P. Lake (Wonga Park, Victoria, Australia) at m(vis)=14.5 on 2011 Feb 14.0969 (JD 2455606.5969), and confirmed shortly after by G. Lubcke (Middleton, WI, USA) at around V=14.4 in time-series observations made simultaneously to the observation of Lake.  Follow-up photometry of this star is encouraged.

Special Notice #233: Bright outburst of the cataclysmic variable SDSS J133941.11+484727.5

February 7, 2011: The star SDSS J133941.11+484727.5 has been reported in outburst by Jeremy Shears (Bunbury, UK).  Shears reports this star at magnitude 10.4 on 2011 February 7.919 (JD 2455600.419).  This is approximately 7 magnitudes above quiescence, which suggests a superoutburst of an SU UMa star or a WZ Sge-like outburst.  Gary Poyner (Birmingham, UK) confirms this outburst, estimating the star at 10.5 on February 7.959 (2455600.459).