Halfway through egress
Greetings. Barely a month from solar conjunction again (early June) and epsilon Aurigae is sinking into the sunset. At the same time, the star has 'taken a breather' - after rising in brightness by 0.5 mag (up nearly 60% in energy terms), the star stalled at V~3.3 during April. A similar still-stand was seen during the 1984 eclipse egress as well, suggesting some persistent opacity around the trailing side of the disk. No clear spectroscopic signatures reported so far, but stay tuned.
Nonetheless, the egress is predicted to end during May, and as many will put the star up on the shelf for another 27 years, some of us will continue to observe and work on data reduction. We encourage everyone in Citizen Sky to continue in one or both modes for at least the balance of the year.
A variety of major telescope observations have been obtained recently as well, including the following:
Gemini North 8 meter GNIRS spectra and NASA IRTF SpeX data both showed the CO features near 2.3 microns has persisted during this egress interval. March 2011 HST/COS spectra continue to show a hot continuum plus emission lines in the UV.
CHARA+CLIMB interferometric data from early April are still being processed, but we hope they will show the egress side of the disk (the CLIMB instrument mode differs from prior observations, as MIRC was out of service). The IRAC imager on Spitzer Space Telescope obtained two samples during April, and these data are part of an effort to detect the warmer side of the disk coming into view as eclipse ends. A series of papers are in preparation.
What's next? Brian, Naomi and I are scheduled to present several talks and posters at the AAVSO/AAS joint meeting in Boston during May, including:
Talks -- Lessons Learned During the Recent Epsilon Aurigae Eclipse Observing Campaign ; Collaborative Research Efforts For Citizen Scientists ; Spots, Eclipses, and Pulsation: The Interplay of Photometry and Optical Interferometric Imaging
"Discovery of Strong Helium 10830A Absorption In The Mid-eclipse Disk Of Epsilon
Aurigae" (Dr.Bob et al.)
"Accretion in the Disk of epsilon Aurigae: Results of Monte Carlo Radiative Transfer
Modelling" (Naomi et al.)
"Towards A Full Orbital Solution For Epsilon Aurigae" (Brian et al.)
plus a poster by Aaron Price et al: "High Speed UBV Photometry of epsilon Aurigae"
and a new entry in the field by John C. Martin and J. O'Brien from U of Illinois Springfield: "Regular High Resolution Full Visual Spectrum Monitoring of Epsilon Aurigae"
Hope to see you there!