Talk

Infrared Studies of the Outer Planets
The outer planets Jupiter, Saturn, Uranus and Neptune have been imaged using a set of infrared bandpass filters each with a band width of 40 nm. Modern infrared digital cameras allow the opportunity to acquire images into the micrometre region of the spectrum. The subtle differences between images using a range of bandpass filters is not obvious. Two methods have been developed to highlight the differences. On a gaseous surface the brightness of a feature at a given wavelength is closely related to temperature. The resulting images show the development and evolution of storms and festoons on Jupiter and lead to a better understanding of the dynamics of the Jovian atmosphere.
Infrared photography also provides a platform for imaging the planets during daylight hours. This is important if a particular feature is to be observed when the planet is near superior conjunction.

Our understanding of the delta Scuti star AD CMi has evolved as observational data since 1959 has gradually accumulated to present a more or less complete picture of its behaviour. Its period is approximately 2 hr 57 min. Data obtained between 1959 and 1992 revealed an O-C (observed minus computed) diagram described by a quadratic function which suggested that the period of the star was increasing slowly at a constant rate. However, the addition of further data, to 2006, revealed a more complicated O-C diagram with a quasi-sinusoidal shape, described by a combined quadratic and trigonometric function. The data implied that, although the pulsational period of the star was indeed increasing at a slow constant rate, the O-C diagram was modulated by the light time effect of a binary system. Data published in 2007 included 81 times of maximum (TOM). We performed photoelectric photometry on one night in 2011 and DSLR photometry during 7 nights in January and February 2016, by which time 9 years had elapsed since the last publication of data in a refereed journal. The literature to 2007 contained 81 TOM, subsequent literature and the AAVSO international database added another 28, and 9 TOM were contributed by our own observations, yielding a total of 118 TOM, by far the largest database in the literature on this star. Assuming a linear ephemeris, the period of AD CMi was calculated to be 0.122974511 (4) d, almost identical to that quoted in earlier literature. Analysis of the O-C diagram confirmed the results of previous authors, and updated most of the coefficients of the function fitted to the diagram. The values of all of the coefficients were statistically significant. We calculated the pulsational period of AD CMi to be increasing at a constant rate of dP/dt = 6.17 (+/- 0.75) x 10-9 d yr-1 or dP/Pdt = 5.01 (+/- 0.61) x 10-8 yr-1. Because estimates of the period of the binary system range from 27.2 y to 42.8 y across four different published papers, it may be decades before an accurate determination of the orbital period can be made from photometric data.

One of the most amazing space missions in history was the Cassini mission to explore Saturn and its moons. After almost 20 years in space NASA's Cassini spacecraft completed its mission in Sept 2017. The Grand Finale took place between April and September 2017. This presentation is a review of the mission especially focusing on the ten most significant discoveries of the mission. The last images of Saturn will be shown.

Large optical telescopes are preferentially sited where astronomical "seeing" is generally of the order of one arcsecond or better. This requires a site altitude of about 2,000 metres or more. Such sites are unavailable in Australia, yet professional optical astronomers in Australia have contributed beyond what might be expected from our population. Amateur astronomers used to be diffraction-limited, but the large telescopes now available to amateurs and especially to societies means that site seeing characteristics (alongside cloudiness and light pollution) are now important. Seeing varies throughout each night, but the median is a site characteristic (possibly seasonally variable). Ways to measure seeing and the data currently available for sites in Australia will be described. Ways in which amateur astronomers can contribute to ongoing measurements will be presented.

The "New world atlas of artificial sky brightness" (Falchi et al., 2016) assumes that night sky brightness at dark-sky sites when the Moon is not visible and there are no clouds is 22.0 magnitudes per square arc second for the V spectral band. However, this depends on the solar cycle and, especially for sites in the southern hemisphere, latitude and sidereal time. Results will be presented, together with a model, for sky brightness in eastern Australia. The model is applicable to any site between latitudes 20 and 43 degrees South, and can be generalized to sites affected by light pollution.

The Internet has brought with it new opportunities for public participation in scientific research. Initiatives such as ‘Zooniverse’ bring together a large community of interested ‘Citizen Scientists’ whose efforts are coordinated by front-line researchers. The catch words for such initiatives include people-powered, discover, teach and learn. Astronomy is one of the flagships of the Citizen Science movement. Automated survey instruments that accumulate large amounts of data, the small numbers of professionally-employed astronomers, and strong public interest in astronomy all provide a strong impetus for citizen science research in astronomy.

Many of the citizen science initiatives require only Internet access with the computer being the research tool. Interests among citizen scientists, however, vary widely with some enjoying being able to collect their own data and make the specialised measurements needed to confirm or augment discoveries made by professional astronomers. Citizen Science accommodates this wide range of interests but a stumbling block for many of those interested in collecting data is the cost of equipment. For example, astronomical CCD cameras with filter wheels and specialised filters cost several thousands of dollars. To properly use such instruments also requires more expensive telescopes and specialised supporting software.

In the past few years there has been a revolution in sensor technology that has seen the introduction of cheap CMOS astronomical cameras. CMOS technology offers not only a cheaper alternative to CCDs but has some other useful advantages including higher quantum efficiency and fast download times for images.

Latrobe University (LTU) runs a first-year astronomy course aimed at a broad cohort of students. Underlying the teaching of this course are the core elements of citizen science – discover, teach, learn; the emphasis being on engendering a lasting interest in astronomy and imparting the basic skills needed for students to participate in citizen science. This paper outlines work at LTU on CMOS cameras for Education and Research in Astronomy.

I will discuss how amateur telescopes can be used to retrace the past 150 years of astrophysics. Amateur telescopes combined with modern detectors are now more capable than professional equipment from a century ago. Amateur astronomers can thus observe the consequences of stellar evolution, the passage of near-earth asteroids, transits of extra-solar planets and the expansion of the Universe. Even the creation of new black holes, via the merger of neutron stars, may now be observable by amateur astronomers. I will discuss the equipment required to make these observations, and show that some observations can be made with relatively basic kit.

Photometric and spectroscopic analyses of V0775 Cen, a near contact binary with a period of 16 hours and TW Cru, a contact binary with a period of 9 h, indicate both are triple systems. The V0775 Cen spectra are consistent with catalogue values of F0 IV for the primary component; its mass is 1.6 solar and radius 1.7 solar. The effective temperature of the secondary star indicates it has a spectral type of about K4, and its mass is 0.5 solar, yet with a radius of 1.1 solar, it has evolved well past terminal age main sequence. Episodes of emission in the H Balmer and metal lines of TW Cru confirm the conclusion from previously published photometric studies that it is chromospherically active.

The Big Skies Collaboration brings together arts practitioners, astronomers, and local communities within a region I've defined as southeastern Australia's 700 Kilometre Array of astronomical observatories, which extends from CSIRO's ATCA near Narrabri, in NW NSW, to Mt Stromlo and Tidbinbilla in the ACT. Our current creative interventions include the Inland Astro Trail, the Skywriters Project, the Wiradjuri Astronomy Project, the Wiradjuri Skywriters Pilot Project, and the Big Skies theatre production to be toured in 2019, the 50th anniversary of the Apollo 11 moon landing. I will be discussing these and other projects and will be inviting NACAA members to be involved. For more, please see bigskiescollaboration.wordpress.com and explore the drop-down menus.

A look at women in astronomy through the ages. Women have made significant contributions to the development of astronomy as a science, yet their work has been restricted, unregarded and little recognized. I will outline some significant careers and show how these talented and determined women overcame the restrictions on their lives to make their marks. Their solid achievements came at considerable cost and attracted little professional recognition.