Southern Maine Astronomers
3 November, 2022 7:00PM
Attending were members Russ Pinizzotto, Paul Howell, Mark H & Caila G, David Gay, Dale Dermot, Rob Thompson, George Bokinsky, Scott, Greg Thorup, Dwight Lanpher, Carole Long, Jim, Craig Snapp, Robert Dodge, Tom, Doug Lund-Yates, David Manchester, Owen, Brad, Kevin Kane, Kerry Kertes, Roy Patrice, Gregory Shanos, Anita Devito, Dale Dermott, Chris Gardner, Jack, Roy Patrice, Alexandra Rudenko, Chris Parent, Maame Andoh, and Robert Burgess, and guest speaker, Thaddeus Komacek.
Reports from Club Members:
Russ Pinizzotto informed the club of his progress with the Astronomical League Open Cluster Observing Program. Russ has now observed up to 84 open clusters. Rob thinks these programs are a benefit to being in the club and an opportunity to learn about the night sky.
John Saucier recounted his recent visit to the Maine Mineral and Gem Museum. According to John, the museum had a room dedicated to meteorites, and visitors were allowed to handle pieces of the moon and meteorites. David Gay confirmed this detail with a story of his visit to the museum, and everyone was amazed at being able to hold a piece of the universe.
Dwight Lanpher had great news regarding his equipment. A few years ago his solar telescope broke and despite getting it repaired, there were still issues with the instrument. He had since been looking for a solar scope and recently, he purhcased a used stacked solar telescope; a significant upgrade to his previous instrument. Dwight is excited to try it out and see how it goes.
Finally, Carson Hanrahan encouraged members to go out and observe Jupiter and Mars. He explained that there's been good observing conditions recently, and the planets are wonderful observing targets.
Club president Rob Burgess had great news on the club’s growth. He reported that the club had gained ten new members since the last meeting, thus putting our membership in the high 90s.
The club had a star party on October 8th at Neptune Drive. There were around 40 attendees, and although the moon was visible, Rob proclaimed that this was one of the best observing nights the club has had.
SMA received a donation of a Celestron-8 telescope from club member Owen Buck.
The club had a Star Party at the Maine Coast Heritage Trust (MCHT) on October 29th. The event was well attended, with 40+ guests and around a dozen club members. The Star Party was in a beautiful location and MCHT is excited to collaborate with SMA in the future.
Rob reminded all attendees that there will be a total lunar eclipse on November 8th. A partial eclipse will begin at 4:09 AM, and the moon will reach maximum at 9:59 AM. The eclipse coincides with the Torrid meteor shower, so it will be a wonderful opportunity to observe both an eclipse and a meteor shower.
The next meeting will be on December 1st. Club member Greg Shanos will be giving a presentation on Mars at Opposition and offering tips on how to observe and photograph it.
There will be a Director’s Meeting on Wednesday, November 16th at 7 PM. As always, all members are welcome to attend.
Finally, the International Dark Sky Association is holding a conference from Friday, November 11th to Saturday, November 12th. The conference attracts representatives from around a dozen countries who give presentations on worldwide efforts to protect dark skies. The conference goes on for 24 continuous hours and tickets can be found on the IDA website.
Our speaker was Thaddeus ‘Tad’ Komacek, an Assistant Professor of Astronomy from the University of Maryland, College Park. Komacek was the recipient of the Heising-Simons 51 Pegasi b Postdoctoral Fellowship at the University of Chicago from 2018-2021. He received his Ph.D. in Planetary Sciences from the University of Arizona Lunar and Planetary Laboratory in 2018, and a Bachelor’s degree in Geophysical Sciences and Physics from the University of Chicago in 2013. Dr. Komacek’s research focuses on defining the atmospheres of exoplanets by developing numerical models for their global circulation and climate.
Komacek began his talk by providing a brief history of exoplanets and their role in astronomy. Astronomers Didier Queloz and Michel Mayor were the first to discover an exoplanet orbiting the Sun-like star, 51 Pegasi. At the time, this type of planet was unexpected, but astronomers have since discovered hundreds of exoplanets. Komacek theorized that the increase in exoplanet detection was attributed to the Transiting Exoplanet Survey Satellite (aka TESS), and the Kepler Space Telescope; both instruments were dedicated specifically to finding exoplanets.
Using Earth as a guide, scientists can identify the key features of temperate rocky exoplanets. These include tropical circulation, and the concentration of irradiation (light from the star) on the equator, and away from the poles.
Most research on exoplanets has focused on the largest and closest exoplanets, referred to as "hot Jupiters''. These are Jupiter-sized gaseous planets that lie close to their host stars. General circulation models predict that hot Jupiters have eastward pointing winds that move hotspots downwind. Most importantly, because exoplanets are so locked in with their host star, there’s severe contrast between the day side, which experiences extremely high temperatures, and the night side, which lies in perpetual darkness with cooler temperatures. In fact, hot Jupiters generally have large (100s to 1000s Kelvin) day-to-night temperature contrasts. These differences are caused by efficient radiative cooling, the process by which temperatures drop at night due to loss of heat on the planet’s surface.
To better understand hot Jupiters, scientists use techniques like transmission spectroscopy to determine the absorption features of exoplanet atmospheres, and measure the planet's orbital velocity and orbital inclination. Scientists also measure the changing size of the planet as a function of wavelength, and use phase curves to compute the planet's relative flux as it orbits its host star.
To illustrate these techniques in action, it is wise to look at the exoplanet WASP-43b. Scientists discovered that during the day side there's more flux as a function of wavelength and extremely high temperatures. As such, daytime provides a better opportunity to observe the absorption features of the planet.
Moving on, there is a distinct type of gasseous exoplanet known as "Ultra-hot Jupiters". The spectra of ultra-hot Jupiters lack significant molecular features. To explain, their near and mid-infrared spectra are blackbody-like due to molecular dissociation. The atmospheres of ultra-hot Jupiters are so hot that compounds are reduced to their molecular components. For example, water breaks up into hydrogen and oxygen atoms. Additionally, due to molecular dissociation, the atmospheres of ultra-hot Jupiters contain high levels of atomic hydrogen on the day side. However, as gas flows to the night side, hydrogen cools and reconverges into molecular hydrogen. This process repeats with the elements being broken down and fused back together depending on the side of the planet they're on.
Interestingly, hydrogen dissociation and recombination reduces day-night contrasts on hot Jupiters. This is because dissociation causes the planet to lose energy, thereby cooling the day side. Then when hydrogen reconvenes, the night side becomes warmer.
Equally important is the cloud coverage of ultra-hot Jupiters. Currently, M-dwarf stars are easier to observe with the techniques and tools available. But tidally locked, slowly rotating sun-like stars are much cooler than our Sun. If their exoplanets have liquid water, then they have thick water clouds. Dayside cloud coverage on tidally-locked planets allows more light to be reflected into space, thereby extending the habitable zone further inwards and promoting habitability. Nevertheless, cloud decks aren't always favorable. Thick cloud decks make it difficult for scientists to measure the planet’s absorption features, thus inhibiting their understanding of the planet's environment. Nevertheless, variability in cloud decks of exoplanets is important as it helps scientists determine how much they should trust their observations.
Although M-dwarf stars and their planets are convenient targets, with the launch of the James Webb Space Telescope, scientists are excited to observe truly Earth-like planets that observe Sun-like stars, instead of M-dwarf stars.
With JWST there is the possibility of searching for biomarkers (signs of life) on Earth-like planets. By observing the atmospheres of these planets, scientists hope to find traces of CO2, oxygen and water in the visible light spectrum, and O3 in the UV light phase. With advanced techniques like high-resolution spectroscopy that produces fine, sensitive, spectral lines, astronomers hope to characterize the atmospheric dynamics of hot and ultra-hot Jupiters and constrain the climates of Earth-sized exoplanets orbiting small stars.
To close off the meeting, Russ Pinizzotto led us on a tour of the constellation Pisces. Because there are few bright stars in Pisces, the constellation can be hard to observe. However, September is one of the better observing months.
Russ began the tour with double stars, 93 and 94 Pisces. One of the pairs is red, while the other is blue, so there is high color contrast. Next is Psi1 Piscium, a binary star system. Following that are the asterisms, ‘The Circlet’, which is found just under the great square of Pisces, and ‘The Rocketship’. Russ also spoke about Testudo, an obsolete constellation discovered in the 18th century.
Russ ended the tour with a series of galaxies: NGC 628, NGC 488, NGC 524, NGC 474, NGC 7541, NGC 383, and CL 0024+1654, a galaxy cluster with a very strong gravitational lens.
December’s meeting tour: Cetus