epsilon Aurigae Newsletters (2009-2012)

2009-2011 #01

Issue: Fall 2006

Summary: First Newsletter of the 2009 Eclipse Campaign.Paul Bechmann of Mendota Heights, Minnesota has started BVRI photometry. Bob Stencel reports on his recent trip to the IAU meeting in Prague. Wolfgang Renz and Gene Lucas have indicated they plan to experiment with short focal length CCD photometry, using a CCD camera with a camera lens in place of the telescope. Stan Gorodenski is in the process of installing a new Meade 16" LX200R in his Bill Hills Observatory in Dewey, Arizona.

2009-2011 #02

Issue: Fall 2007

Summary: The Hopkins Phoenix Observatory continues UBV photometry of epsilon Aurigae. Bob Stencel discusses some objectives for this eclipse and the methods which are best suited to realizing them. There are a series of papers which are quite useful to review including:

2009-2011 #03

Issue: Winter 2007/2008

Summary:

AAVSO declared the “variable Star of the Year - Epsilon Aurigae.” They intend to have a “capstone” project for the International Year of Astronomy 2009 involving the monitoring of epsilon Aurigae (edit: this became Citizen Sky).

Robert Stencel provides an overview of the campaign and re-establishes the scientific objectives.

Several observers have formally joined the campaign including:

2009-2011 #04

Issue: Winter 2008 (Feb. 2008)

Summary: More members have joined the campaign. Jeff Hopkins provides details about a 66-day quasi period that has developed. Brian McCandless, Lothar Schanne, Serdar Evren, and Robert Stencel (a.k.a. “Dr. Bob”) provide communications. In particular, Dr. Bob discusses new interferometric observations obtained at the Palomar Testbed interferometer.

2009-2011 #05

Issue: Spring 2008

Summary: Jeff presents an abstract for a paper entitled “Gearing Up for Epsilon Aurigae’s First Eclipse of the Millennium. Observing reports from Lothar Shanne, Robin Leadbeater, Richard Miles, Hans Lindberg, Jim Fox, and Brian McCandless.

Dr. Bob discusses the PTI observations as well as spectral evolution of Sodium.

2009-2011 #06

Issue: Summer 2008

Summary: Standard stars for photometric observing campaigns are established along with suggested V, B-V, U-B, V-Rj, R-Ic, and V-Ij. Trends from previous eclipses are discussed. Discussions from Paul Beckmann about photometry is included. Dr. Bob’s text includes about a press conference held at the AAS meeting entitled “ASTRONOMERS PREDICT NEARBY STELLAR FIREWORKS BY MID-CENTURY.” A predictive “calendar of events” for the 2009-2011 eclipse is also included.

There are several references to literature in this document as well.

2009-2011 #07

Issue: Summer 2008

Summary: Observing reports from David Daiku, Bruce Grim, Paul Beckmann, and Jeff Hopkins. Stan Gorodenski reports on ongoing spectroscopy. Dr. Bob reminds the readers that there are still a few copies of the 1985 NASA conference proceedings on eps Aur in printed form.

2009-2011 #08

Issue: Fall 2008

Summary: A standardized header is now required for publication of participant’s data on the website. Several campaign members have reported news and additional observations in several different filters. Mike Sitko reports on Mid-IR observations using the Broad-band array Spectrograph (BASS) at IRTF.

Several pages in the newsletter are dedicated to spectroscopic observations. They highlight spectroscopic lines that are both scientifically interesting and easily observed. Brian McCandless and Jim Edlin includes a short summary of their H alpha observations. Dr. Shane and Dr. Stahl have setup an archive for epsilon Aurigae spectroscopy stored here, here, and here.

Dr. Bob discusses the work of Elisabeth Griffith who is digitizing historic spectroscopic photographic glass plates. He also indicates that the epsilon Aurigae interferometry paper has been submitted (edit: and subsequently published). The first interferometric observations at CHARA have been scheduled for 2008 Dec.

2009-2011 #09

Issue: Fall/Winter 2008

Summary: Jeff provides comments on photometry of eta Aur. and zeta Aur. Des Loughney discusses methods for using a DSLR camera for accurate photometry. Observer reports from Des Loughney, Neil Short, David Trowbridge, Brian McCandless, Tiziano Colombo, Richard Miles, and Jeff Hopkins. Robin Leadbeater discusses how the Star Analyzer can be used on a DSLR or CCD camera to do low resolution spectroscopy. Spectroscopic reports from Robin Leadbeater, Bruce McCandless, Jim Edin and Lothar Schanne.

Dr. Bob comments on polarimetry from the 1983 eclipse acquired by the late Jack Kemp which show “stochastic changes” on timescales of 0.5 to 5 days. He also includes a paragraph long discussion of the Palomar Testbed Interferometry (PTI) paper published prior to the release of this newsletter.

2009-2011 #10

Issue: Winter 2008

Summary: In the preface to this edition there is a brief discussion of EE Cephei project (another eclipsing binary system with a disk). The 2009 March 03 eclipse of zeta Aurigae is also discussed. Aaron Price from the AAVSO has a page discussing an IYA event centered around epsilon Aurigae (later called Citizen Sky.

Photometry reports from Neil Short, David Trowbridge, Des Loughney, Brian McCandless, Richard Miles, Jeff Hopkins, Frank J. Melillo Dr. Tiziano Colombo. Spectroscopic reports from Oliver Thizy, Nadine Manset, Jeffrey Hall, and Jeff Hopkins.

Dr. Bob’s comments focus on high resolution spectroscopy and photometric observations with several references to important things to observe.

2009-2011 #11

Issue: Spring 2009

Summary: This issue advertises the opportunity to go observing before the ingress phase begins. The introduction includes mention of several other observing campaigns at BAA VSS and Vereniging voor Sterrenkunde (link broken),

Photometric reports from David Trowbridge, Dr. Tiziano Colombo, Richard Miles, Paul Beckmann, Des Loughney, Brian McCandless, Jeff Hopkins, and Frank J. Melillo. Spectroscopic reports from Robin Leadbeater (Potassium Line), Benji Mauclair (Hydrogen Alpha), Joel Eaton (Texas state University covering Hydrogen Alpha), Brian McCandless (Ha & 7000-7500 Å), and Jeff Hopkins (Hydrogen Alpha Summary) are included.

Jim Beckmann provides a few page summary of his observatory and photometric equipment.

Dr. Bob comments on his work with Brian Kloppenborg to do JH photometry of epsilon Aurigae using an Optec SSP-4 photometer. Preliminary JH photometry is reported. He also discusses some interesting results coming out of the Dominion Astrophysical Observatory courtesy of Elizabeth Griffin. Lastly, observations BASS, MIRIS, Spitzer Space Telescope (MIPS), XMM (X-ray), and interferometric data from CHARA and PTI has been obtained. Dr. Bob also opened a twitter account for epsilon Aurigae news.

As usual, several interesting upcoming papers are also included in the last few pages.

2009-2011 #12

Issue: Spring/Summer 2009

Summary: This is the last observing opportunity before ingress! Numerous photometry and spectroscopy reports are included in this and subsequent issues (see the index page for details). Around this time Dr. Bob and Brian Kloppenborg started blogging on the Citizen Sky website. Many of Brian’s posts are duplicated here.

Dr. Bob emphasizes the research objectives again and a few things for which observers should be looking. These include differences in totality length, flares, and transient spectroscopic features.

2009-2011 #13

Issue: Summer 2009

Summary: This final pre-eclipse newsletter. The document contains pre-eclipse photometry and spectroscopy reports from more than 10 observers. Brian Kloppenborg announced the release of his alternative control software for the SSP-4. Dr. Bob discusses the Society of Astronomical Sciences meeting, and ongoing JH photometry at the University of Denver.

2009-2011 #14

Issue: Summer/Fall 2009

Summary: This issue marks the first release of the newsletter during the 2009-2011 eclipse. First contact occurred somewhere around August 30, 2009 (this was later refined in a JAAVSO publication by Hopkins et al.). As usual, there is plenty of photometric and spectroscopic data being discussed.

The newsletter now contains a data disclaimer which establishes the data belongs to the person who originally acquired the data. You must get their consent before publishing their work.

The director of the AAVSO, Arne Henden, provided a brief discussing data archiving practices at the AAVSO. It should be noted that the AAVSO policy is markedly different than the newsletter.

Dr. Bob discusses eclipse timing, the initial reductions of daytime JH photometry of epsilon Aurigae taken at the Mt. Evan observatory, and the recent Citizen Sky workshop held at the Adler Planetarium in Chicago.

2009-2011 #15

Issue: Fall 2009

Summary: A total of 48 observers are now participating in the observing campaign. A standardized set of UBVRjIjJH magnitudes for lambda Aurigae have been provided in this document. Gary Cole reports on broadband polarimetry observations.

The zeta Aurigae secondary eclipse happened on 2009 Nov. 17 and is briefly discussed here. This eclipse is not very exciting for optical photometrists, but is quite pronounced at infrared wavelengths.

2009-2011 #16

Issue: Winter 2009/2010

Summary: As the eclipse continued additional observers registered with the campaign. We are now up to 55 observers. In the preface Jeff provides revised first contact estimates. A new epsilon Aurigae forum was created on Yahoo Groups which is used for general communication / email list purposes.

Photometry and spectroscopy reports continue to pour in. Robin Leadbeater has several pages discussing his observations of the KI 7699 line. He reports a series of steps in equivalent width growth which he interprets to be rings in the disk.

Dr. Bob provides a short report on the interferometric observations at CHARA stating that the initial images “clearly show the disk ingress across the F star.” (edit: as we had just submitted the paper to Nature, we could not provide images for this newsletter). He also provides a view of the Hoard, Howell, and Stencel comprehensive SED for the system as being composed of the F-star, a cold disk, and a B-type companion.

2009-2011 #17

Issue: Winter/Spring 2010 (totality)

Summary: Jeff Hopkins and Robin Leadbeater now share co-editorial responsibilities in the newsletter. Jeff is handling the photometry, Robin the spectroscopy. Both of the editors call for continued observations, especially near the mid-eclipse time frame which is thought to feature a see-through/transparent disk.

A guest post by Dr. Phil Bennett cautions on changes that will be required to obtain good photometry during this time period. He raises several concerns involving photometry that could be skewed by the high airmass (observing some 9 degrees above the horizon) during mid-eclipse.

Photometry continues to accrue. The photometric charts by Brian McCandless (see pg. 26) are fairly impressive, showing BVRIJH plus WingA WingB, and WingC filters. The stair step nature seen in Robin Leadbeater’s KI equivalent width plots continues to be interesting. It is essentially following the same sequence as seen in previous works by Lambert & Sawywer seen during the previous eclipse, but the higher cadence makes the pattern much more obvious.

Dr. Bob discusses the interferometry (releasing the first images of the transiting disk), polarimetry, and highlights three key developments during the 2009-2011 eclipse.

2009-2011 #18

Issue: Summer 2010 (totality)

Summary: This issue immediately follows mid-eclipse and features an impressive light curve composed of data from more than a dozen observers.

Robin summarizes that 61 additional spectra have been submitted to the campaign from amateur astronomers. They are archived on his website.

Dr. Bob provides a short summary on the next round of interferometric imaging efforts at CHARA. Polarimetry by Gary Cole, Gary Henson and Nadine Manset continues.

2009-2011 #19

Issue: Fall 2010 (the second half of totality)

Summary: There are several conference and trip report summaries (including Jeff’s visit to CHARA). The photometry plots have been updated.

Robin over plots his KI observations with the previous work of Lambert and Sawyer which shows the eclipse is progressing very similarly to last time. The radial velocity of the H alpha line shows some form of jump discontinuity which has not been seen in previous eclipses. Robin also reports on photographic glass plate spectra found in the Norman Lockyer Observatory archives taken in 1921.

Dr. Bob discusses observations with the Hubble Space Telescope, CHARA interferometer, and NASA’s Infrared Telescope Facility (IRTF) and their particular research objectives.

2009-2011 #20

Issue: Fall/Winter 2010/2011

Summary: Jeff summarizes a trip he and Dr. Bob took to Mt. Hopkins to observe at MMT using the Mid-Infrared Array Camera 4 (MIRAC4). On page 6 Jeff totals the number of observations submitted to the campaign to be nearly 2600 (UBVRcRjIcIj filters) since the start of the campaign. We are now roughly three months away from third contact.

During Jan. 2011 the AAS 217 meeting was host to a special session on epsilon Aurigae which is briefly discussed in this newsletter.

Dr. Bob summarizes a slew of data from the UV to mid-IR.

2009-2011 #21

Issue: Winter 2011 (right before third contact)

Summary: Several pages in this newsletter are dedicated to summarizing the 217 AAS meeting (edit: these notes are posted elsewhere on the website). A group photo showing Brian Kloppenborg, Elizabeth Griffin, Dr. Bob Stencel, John Clover, Jeff Hopkins, Bill Ketzeback Will’s wife, Tom Ake, and Greg Jones is included on page 4.

Five pages are dedicated to a photometric report from Richard Miles discussing comparison and check stars in the surrounding star field. This revealed that his comparison star (HD 32655) was a variable and polluted his photometry. Having a good check star nearby saved his data.

Since the last newsletter and this one, an additional 85 spectra have been submitted. Robin’s updated KI plot shows an excess of equivalent width compared with the Lambert & Sawyer (1986) data.

There are also several pages about data from the Apache Point Observatory taken by William Ketzeback. These data are high (R=31500) and medium (R=3500) spectra taken in the optical and near infrared respectively. (edit: note we have migrated the AAS posters over to a dedicated directory on this website, see AAS 217 for more information).

Dr. Bob’s section largely reflects on the posters and talks at the AAS 217 meeting.

2009-2011 #22

Issue: Spring 2011 (third contact)

Summary: More than 3100 UBVRI observations have been contributed to the campaign. At present we are just about a month away from fourth contact and are right in the middle of the 3rd contact “knee” seen in previous eclipses (although not well documented, see pg. 8 of this newsletter for one of the better figures showing this phenomena).

Piotr Wychudzki has a nice discussion of airmass effects on the epsilon Aurigae light curve showing that airmass can negatively impact the resulting light curve if not carefully corrected.

Spectroscopists are reporting that several lines have become doubled.

Dr. Bob includes a list of data from Gemeni, ITF, HST, CHARA and the Herschell Space Observatory that are soon to be acquired for which supporting ground-based data are useful. He also reports on the discovery of the He 10830 absorption line seen during mid-eclipse, indicating a hot (> 25,000K) plasma must exist in the middle of the disk. This sets lower limits on the type of star contained inside of the disk.

2009-2011 #23

Issue: Summer 2011 (fourth contact)

Summary: The photometric observations during this eclipse now total more than 3500 from 26 observers. Jeff provides some summarizing text discussing the dates for contact times, average eclipse depths, and total eclipse times in each photometric filter.

The spectroscopists are reporting that even though the photometric eclipse has ended the spectroscopic eclipse has NOT ended and continued monitoring is required.

2009-2011 #24

Issue: Fall/Winter 2011 (final newsletter)

Editor’s Remark:

We have completed a most successful Campaign to observe the latest eclipse of the Epsilon Aurigae star system. Observers from around the world have provided an unprecedented amounts of photometric and spectroscopic observations. Things have changed greatly since the 1982/84 eclipse because of the Internet, personal computers, CCD cameras and excellent quality yet reasonably priced spectroscopic equipment. It strains one’s mind to imagine what will be available for the next eclipse in 27 years.

Continued Observations

Remember, even out-of-eclipse epsilon Aurigae presents some very interesting observing and through that continued observations both via photometry and spectroscopy may shed some light on the still unanswered questions about Epsilon Aurigae.

Photometry

There is an out-of-eclipse photometric variation that seems periodic, but defies efforts to pin down a period or periods. It seems to be between 50 and 70 days, but even that is not fixed. The amplitude changes are also varied and appear random. This is in all photometric bands.

Spectroscopy

From spectroscopy the hydrogen alpha emission horns continue their delightful and mysterious dance. One might think there is a correlation to the out-of-eclipse variations, but no such correlation has been found. There may be other spectroscopic lines that are changing and of interest. The sodium D lines for example. The fall of 2011 present another unique opportunity. The eclipse of zeta Aurigae was timed to place it in an excellent observational position. A Zeta Aurigae Campaign was started with both photometric and spectroscopic observations reported. This Newsletter has a summation report for that Campaign.

Closing remarks

I wish to thank all those who contribute to this Campaign making it a success. In particular I wish to thank Frank Melillo for his enthusiasm and help as well as his valuable photometric and spectroscopic data.

Old age is quickly catching up with me and the Epsilon Aurigae is my final photometric project. I intend to continue spectroscopy work, however. The Epsilon Aurigae Campaign Web Site will be handed off to Brian Kloppenborg early in 2012 (edit: due to my dissertation this didn’t happen until the end of 2012). He will be maintaining it as he continues his study of Epsilon Aurigae. I will make an announcement when the change happens and while the original site will go away, I will provide a link from it to the new site.

It has been an honor to work with all the observers and an exciting time presenting papers, visiting the CHARA Observatory on Mount Wilson in Southern California to see Brian Kloppenborg make Interferometry Observations of Epsilon Aurigae and to visit Mount Hopkins in Southern Arizona and see Dr. Bob use the 8 meter telescope to do far infrared observations of Epsilon Aurigae.

Again I wish to thank the several dozen observers who contributed data to the Campaign. I especially wish to thank Dr. Bob for his enthusiasm, guidance and help with the Campaign. (edit: I too thank Dr. Bob for his excellent work leading the professional side of this campaign. The shear quantity of data we collected is staggering and seeing it get processed and published is even more amazing.)