PRESS RELEASE AND PRESS CONFERENCE PRESENTATION

• Press Release → PDF
• Press Conference Presentation → PDF

Harvard College Observatory The Harvard College Observatory, on Observatory Hill in Cambridge Massachusetts, houses the world’s largest (half a million) collection of astronomical photographs. The collection is housed on many floors in the left half of the building shown. The star pictures go back to 1890, with every part of the sky covered by 1000-3000 photos. So for every star (not too faint), the Harvard plates can provide a measure of its brightness changes back to 1890, and this is the unique capability that allows for pulling front-line astronomy from these archives.

Photograph cabinet at Harvard College Observatory The Harvard College Observatory has a collection of half-a-million astronomical photographs going back to 1890. This cabinet contains around 1500 glass plates (each 8”x10” all in protective envelopes) with photographic emulsion on one side showing images of star fields containing up to a million stars on each plate.

Glass plates on light table for examination Two glass plates have been slid out of their protective envelopes for examination with a handheld loupe (small black object on table in front of light box). The plates are leaning against a light table, with a lamp inside providing a backlight for examining the individual stars appearing on the emulsion side of the plate. The papers on the left side of the light table are a sky chart to help in identifying the stars of interest.

Typical plate at Harvard showing Sagittarius TIFF - PDF This plate shows the star fields in Sagittarius, with the rich Milky Way ‘clouds’ easily visible in the center of the lower half. The bright pair of stars with surrounding nebulosity near the center is the famous Trifid Nebula. The red marking are put on the clear side of the glass plate (not on the side of the glass that has the emulsion!) to help locate the stars. The labeled regions are centered on various nova in Sagittarius (e.g., V1016 Sgr, BS Sgr, and V4444 Sgr) for examination. The brighter stars can be seen in this picture, but a myriad of fainter stars can be seen when the plate is examined under a microscope.

Discovery plate for the 1900 eruption of Nova Ophiuci 1998 TIFF - PDF Nova Ophiuci 1998 was predicted by Ashley Pagnotta (Louisiana State University) to actually be a recurrent nova, with multiple eruptions within every century. To test such a prediction, we could either monitor the star every week for the next century, or we could look at archival plates for the last century. By looking through ~3000 old sky photos, Ashley Pagnotta found this plate at Harvard Observatory (plate AM505) which shows the nova bright back on June 20, 1900. The picture shows a close up of the area around the nova, with the nova indicated by an arrow. All the ordinary stars appear as short streaks, which is simply caused by the telescope slightly moving during the 60-minute exposure. The discovery of the 1900 eruption provides confidence in the basis for Pagnotta’s prediction.

Sonneberg Observatory in Thuringen, Germany The Sonneberg Observatory has the world’s second largest collection of archival astronomical photographs. Roughly 300,000 sky photos are stored in the ground floor of this building, with coverage going back to the 1920’s. Unique in the world, the photographic sky patrol is still ongoing, using a bank of telescopes housed in the flat roll-off structure on the left side of the roof.

Shelves filled with boxes full of old photographs at Sonneberg Observatory The photographs at Sonneberg come in various sizes and are stored in boxes sorted by position on the sky. Each photograph is a glass plate with a photographic negative emulsion on one side. The sky photos at Sonneberg extend back to the 1920’s, but most are from the 1950’s to the present time. This is a remarkable match with the Harvard plates which start in 1890 but largely come to a stop in 1953. By combining the coverage from both Harvard and Sonneberg, modern astronomers can get a complete history of the brightness of any star from 1890 to present. For many science questions, the only way to answer them is with a long time coverage, and such cannot be bought with any combination of modern telescopes.

Examining the faint stars with a microscope The old astrophotos in Sonneberg Observatory are examined through a microscope with a back-illuminating lamp. Here, Ashley Pagnotta (Louisiana State University, Department of Physics and Astronomy) is looking at a photograph of Nova Ophiuci 1998 (V2487 Oph), for which she had earlier discovered a nova eruption in June 1900. This discovery proved her prediction that the star was a recurrent nova. The picture here shows her looking for more eruptions. The white gloves are worn to avoid degrading the emulsion on one side of the glass plates.

RECURRENT NOVA RESULTS

Summary →	PDF
Light Curve Templates →
Spectral Energy Distribution →
Distribution in Galaxy →
RN Colors in Quiescence →

Abstract from the American Astronomical Society meeting in Long Beach, California: Talk 320.04 on 6 January 2009 - PDF
Slides from talk - PDF

Bradley E. Schaefer    (Louisiana State University)

The identity of the progenitor systems for Type Ia supernovae has been a big problem for forty years. This has recently risen to high importance for all the supernova cosmology programs where the progenitor needs to be known for evolution corrections. A likely progenitor is the recurrent novae (RNe), in which a near-Chandrasekhar mass white dwarf is being loaded with material at a high rate. But there are two big questions for RNe as progenitors; first whether the RN death rate equals the supernova rate and second whether the white dwarf is gaining mass over each eruption cycle. For these two questions, three parameters are required to be measured for many RNe; the recurrence time, the discovery efficiency, and the pre-eruption orbital periods. Previously, these quantities have factor-of-3 errors, two orders-of-magnitude errors, and complete lack of information, respectively. The only way to find these values is with archival data. For the recurrence time, I have exhaustively searched the world's archival plate collections and other archival records and have found seven previously-undiscovered eruptions. For the discovery efficiency, I have searched for second eruptions of 'classical novae', quantified the limits and observing cadences of archival plates, all LMC and M31 nova searches, and amateur nova hunters from 1890 to present, and tested archival data of old 'classical novae' for RN indicators. My conclusion is that roughly one-third of all 'classical novae' are really RNe with two-or-more eruptions in the last century. The only way to get pre-eruption orbital periods is with old archival data, for which I now have highly accurate period changes across eruptions for two RNe.

Abstract from the American Astronomical Society meeting in Long Beach, California: Poster 491.04 on 7 January 2009 - PDF
Poster with all light curves and results - PowerPoint

COMPREHENSIVE PHOTOMETRIC HISTORIES OF ALL KNOWN GALACTIC RECURRENT NOVAE

Bradley E. Schaefer    (Louisiana State University)

I collect virtually all photometry of the ten known galactic recurrent novae (RNe) and their 37 known eruptions. This consists of my modern measures of nearly all archival plates (providing the only data for half of 37 known eruptions), my own 10,000 CCD magnitudes from 1987 to present (providing virtually all of the magnitudes in quiescence for seven RNe), over 140,000 visual magnitude estimates recorded by amateur astronomers (who discovered half the known eruptions), and the small scattering of magnitudes from all the literature. From this, I produce various uniform products; (1) BVRIJHK comparison star magnitudes and BV comparison star sequences to cover the entire range of eruption, (2) complete light curves for all eruptions, (3) best fit B and V light curve templates, (4) orbital periods for all-but-one RN, (5) exhaustive searches for all missed eruptions, (6) measured discovery efficiencies since 1890, (7) true recurrence time scales, (8) predicted next eruption dates, (9) variations on time scales of minutes, hours, days, months, years, decades, and century, (10) uniform distances and extinctions to all RNe, (11) BV colors at peak and UBVRIJHK colors at minimum all with extinction corrections, and (12) the spectral energy distributions over UBVRIJHK. Highlights of this work include the discoveries of one new RN, six previously-undiscovered eruptions, and the discovery of the orbital periods for half the RNe. The goal of this work is to provide uniform demographics for answering questions like the `What is the death rate of RNe in our galaxy?' and `Are the white dwarfs gaining or losing mass over each eruption cycle?'. An important use of this work is for the question of whether RNe can be the progenitors of Type Ia supernovae.

LIGHT CURVES FOR ALL RECURRENT NOVA ERUPTIONS

PLOTS:
T Pyx →	T Pyx-1902 - T Pyx-1920 - T Pyx-1944 - T Pyx-1966
IM Nor →	IM Nor-1920  -  IM Nor-2002
CI Aql →	CI Aql-1917 - CI Aql-1941 - CI Aql-2000
V2487 Oph →	V2487 Oph-1998
U Sco →	U Sco-1863 - U Sco-1936 - U Sco-1945 - U Sco-1969 - U Sco-1979 - U Sco-1987  -  U Sco-1999
V394 CrA →	V394 CrA-1949 - V394 CrA-1987
T CrB →	T CrB-1866 Eruption - T CrB-1946 Eruption - T CrB-1941-1947
RS Oph →	RS Oph-1898 - RS Oph-1907 - RS Oph-1933 - RS Oph-1945 - RS Oph-1958 - RS Oph-1967 - RS Oph-1985 - RS Oph-2006
V745 Sco →	V745 Sco-1937 - V745 Sco-1989
V3890 Sgr →	V3890 Sgr-1962 - V3890 Sgr-1990

TABULATION OF ALL MAGNITUDES IN LIGHT CURVES

T Pyx →	PDF
IM Nor →	PDF
CI Aql →	PDF
V2487 Oph →	PDF
U Sco →	PDF
V394 CrA →	PDF
T CrB →	PDF
RS Oph →	PDF
V745 Sco →	PDF
V3890 Sgr →	PDF
AAVSO data for T Pyx (1967), IM Nor (2002), CI Aql (2000), RS Oph (1933, 1945, 1958, 1967, 1985, 2006) → PDF

   Last Update: Tue, 06-Jan-2009 10:53 AM