Proposal #180

NO Pup is a southern (126.57388, -39.05894) eclipsing binary with a surprisingly eccentric orbit (e=0.13) for its short period (1.257 days), resulting in a very fast apsidal motion (U = 37.2 yr). The system was discovered in 1972, and has not attracted heavy attention since then despite this unusual orbit.

A team (of amateur or retired astronomers) led by Dr. Edwin Budding in New Zealand has obtained spectroscopy of this system from Mount John Observatory. We would like to have a student at National University of Singapore (NUS) reduce these data. It would be helpful for the student to reduce and analyze Johnson BV (or narrower filters if available) photometry of the system, combining this with the spectroscopic reduction. The combination of data reduction and subsequent analysis should make for an interesting data handling project for the student, who would then move onto statistical modelling of the processed data.

Dr. Budding and I have supervised honours research projects at NUS since 2014, with some of the better students being published (further details can be found in https://arxiv.org/abs/1906.08610, https://arxiv.org/abs/1906.08777, and https://arxiv.org/pdf/2006.09552.pdf). The objective would be for the student to complete their thesis on this system, through to a research publication. TESS data are also available for NO Pup, and would be included in the overall study (along with Gaia and Hipparcos), but are surprisingly noisy (especially when compared with the light curves shown in Gronbech, 1976, A&A, 50, 79). The team has a reasonable publication record (e.g., https://scholar.google.com/scholar?hl=en&as_sdt=0%2C14&q=edwin+budding&btnG=, https://scholar.google.com/citations?user=JpU1J6EAAAAJ&hl=en&oi=ao).

The BSM network looks ideal for this system, which is too bright for the instruments we typically use for photometry. We hope that this proposal would be of interest to AAVSO, and if so would appreciate advice on suitable exposure times, as well as cadence given the load on the network. Naturally we would like to collect a well defined light curve fairly quickly given the apsidal motion of 0.81 degrees per month. We would be using software such as WinFitter (a synthetic light curve modeller) to analyse the light curve. Data analysis could be with VPhot or AstroImage. The student project would not begin until June 2021 ('summer' holidays in Singapore), thesis submission would be in March 2022, and defence would likely be in late April/early May 2022. We would like to collect the data ahead of the student formally starting, given the relatively short project time for them, it also helps ensure that the student has a viable project.

NO Pup would be the third system in a paper series looking at early type (B) eclipsing binaries --- the first two papers are on V Pup (accepted by MNRAS) and PU Pup (in final preparation for submission). We believe the system is overdue for a detailed examination. The study of the previous systems provided surprises, such as micro-pulsations in V Pup as the primary enters the instability strip. We expect surprises from NO Pup.

I'd be happy to answer any questions. My AAVSO observer code is BTSB. NO Pup is already well placed for observation. The following URL plots the airmass end of January for Siding Spring, Australia: https://astro.swarthmore.edu/plot_airmass.cgi?observatory_string=-31.277039%3B-210.933914%3BAustralia%2FSydney%3BAnglo-Australian+Observatory+%2F+Siding+Spring&use_utc=0&observatory_latitude=&observatory_longitude=&timezone=UTC&start_date=01-29-2021&target=no+pup&ra=&dec=&invert=0&max_airmass=2.4

Best Wishes

Timothy Banks