Author Archives: Greg Scheiderer

Calendar: Six NW astro-club meetings this week

Orbit Around October continues at the Museum of Flight, and there are a slew of astronomy club meetings on the calendar for this week.

Orbit

Orbit Around OctoberThe Museum of Flight continues its spacey month with a visit to Ceres at 2 p.m. Saturday, October 21. Johns Hopkins University Applied Physics Lab participating scientist Debra Buczkowski will talk about the discoveries of NASA’s Dawn mission to the giant asteroid Vesta and dwarf planet Ceres. Buczkowski will discuss what we learned about Vesta and Ceres, and how this helps us understand the formation of bodies in the asteroid belt. Free with museum admission.

Star party in Oak Harbor

The Island County Astronomical Society plans its monthly star party in Fort Nugent Park for around dusk on Friday, October 20.

Haunted night sky

The popular planetarium show Haunted Night Sky continues on Saturdays through October at the Pierce College Science Dome. Show times for October 21 are 12:30 p.m. and 2 p.m., and the program runs about 45 minutes. The show is designed for kids ages 3–12. Tickets are $6 for children, free for adults, and are available online.

Astronomy club meetings

There are half a dozen astronomy club meetings in the region this week:

Mark your calendar

The next Astronomy on Tap Seattle event is set for 7 p.m. Wednesday, October 25 at Peddler Brewing Company in Ballard. The theme will be “A Hitchhiker’s Guide to the Galaxies” and the evening will feature talks about galaxy types, formation, and evolution. Plus beer and astronomy trivia.

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Seeing the invisible and finding aliens using polarimetry

The topic line for last week’s gathering of Astronomy on Tap Seattle was What the Hell is Polarimetry?, and it seemed that a significant portion of the audience at Peddler Brewing Company in Ballard shared the question.

UW postdocs Jamie Lomax and Kim Bott explained that when light starts from its source the oscillation of its wave—its “wiggle”—goes in all directions until an interaction with something makes it polarized.

“That just means that it’s wiggling in one direction,” Lomax noted. “There’s a preferred plane for that wiggle to happen in, and in polarimetry what we’re doing is measuring that preferred plane and we’re looking for light that has been polarized.”

“It can help you figure out the shape of things without having to resolve the object,” Bott added.

Polarimetry and massive stars

Lomax studies massive stars and has found use for polarimetry in her work. She gave a talk titled, “Seeing Invisible Circumstellar Structures.”

Jamie Lomax

Jamie Lomax

“The holy grail for us in massive star research is to be able to take a massive star at the beginning of its lifetime, figure out how massive it is,” Lomax said, “and map out what its life is going to look like and figure out what supernova it’s going to end its life as.”

“It turns out that is really hard, and it’s complicated by the fact that most massive stars are probably in binary systems,” she added. Since about two-thirds of massive stars are part of a binary system, one might expect that two-thirds of core-collapse supernovae would be from such systems.

“There’s a problem, and that is we’ve only seen maybe two or three core-collapse supernovae where we have evidence that suggests that it’s come from a binary star,” Lomax said.

Part of the problem, she said, is that we don’t yet know enough about the evolution of binary star systems.

“We can try to hammer out the details of how that mass is transferring between the two stars and when the system is losing material to try to figure out how that effects its future evolution,” Lomax said. “Once we start answering questions like that we can start to tease out why we aren’t seeing all of these binary supernovae we think we should be seeing.”

Lomax talked about the star Beta Lyrae, a binary system. The primary star in the system is losing mass that gets gobbled up by the secondary. This transfer of mass also forms a thick accretion disk of gas around the secondary—so thick light from the actual star can’t get through. There’s also evidence that there are jets shooting out of the system, but we don’t know where they are.

“These are all features that we can’t see very well,” Lomax said. “We can’t see the mass transfer stream between the two stars, we can’t see the jets.”

Here’s where polarimetry comes in. If a star is surrounded by a cloud of gas or dust that is circularly symmetrical, when the starlight interacts with that material the light becomes polarized, and the wiggles line up tangentially with the edge of the disk. If the cloud is elongated in some way, the wiggles form in a “preferred” direction.

“That preferred wiggle direction is 90 degrees from the direction of the elongation of the disk, so you can back out geometric information pretty quickly,” Lomax said. “Just by looking at how the light is wiggling I can tell you how the disc is oriented on the sky.”

Lomax figures that if you don’t do polarimetry you’re throwing out free information.

“You can see invisible things—to you—and that gives you extra information about what’s going on in different systems.”

Exoplanets and aliens

Bott’s talk was titled “The Polarizing Topics of Aliens and Habitable Planets.” She studies exoplanets and said polarimetry comes in handy.

“Stars don’t produce polarized light, which is really great if you’re trying to look at something dim like a planet,” she noted. The polarimeter will simply block out the starlight. There are then a number of things that might be spotted on the planet:

  • Glint from an ocean
  • Rayleigh scattering
  • Clouds and hazes
  • Rainbows
  • Biosignatures of gases in an atmosphere
  • Chiromolecules
Kim Bott

Kim Bott

These can help astronomers characterize a planet, judge its potential habitability, and even determine if life might already be flourishing there.

Bott said that polarimeters that are sensitive enough to study planets are a recent advance, and they’re studying big, bright planets to get the hang of it. Looking for rainbows can be revealing about liquids in the atmosphere of a planet.

“The light will bend in the droplets at a slightly different angle depending what the droplet is made out of,” Bott said, so they can tell whether its water, methane, or sulfuric acid.

“We’re trying to create these really robust models that will take into consideration polarized light from Rayleigh scattering in the atmosphere as well as from rainbows,” Bott said, “and if you have a planet where you can see the surface you’d be able to see the signature from glint as well.”

Since different substances bend light at different angles, we can also learn a lot by watching closely as planets move through their phases as they orbit their host stars.

“On Earth we have light going from air and bouncing off of H2O water,” Bott said. “That’s going to produce a maximum in polarized light at a different angle than on, say, Titan, where you have light going from a methane atmosphere and then bouncing off of a hydrocarbon ocean.”

“We can actually, in theory, tell what the ocean and atmosphere are made out of by looking at where, exactly, in the orbit we see this glint,” Bott explained.

As for aliens, life requires more complex molecules, chiromolecules, that are “wound” in a certain direction, like our own DNA. Such molecules would produce circularly polarized light, which if detected could be a sign that such molecules exist on the planet.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington. It’s next gathering is scheduled for October 30 at Peddler Brewing Company in Ballard.

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Astro Biz: Star Brass Works

Star Brass WorksMany businesses, products, and places have names rooted in space and astronomy. We’re featuring one every Tuesday on Seattle Astronomy.

This week’s Astro Biz is the Star Brass Works Lounge. The lounge is in the historic Star Brass Works building on Airport Way in Georgetown just south of Gerogetown Playfield. The building was for some 40-plus years the home of a company called Star Brass Works, which forged pressure-release valves there, and the bar kept the name. The lounge features a full bar, large indoor seating area, and a big patio.

More info:

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Calendar: Orbit around October

A month of space and astronomy events are on the calendar at the Museum of Flight, with three events kicking it all off this week.

Orbit Around October

Orbit Around OctoberThe museum’s space month is dubbed Orbit Around October, with new events on Saturdays during the month.

It all starts off on October 5 with Astronomy Night during the museum’s monthly Free First Thursday. There’s no admission charge between 5 p.m. and 9 p.m. Area astronomy clubs will be on hand with telescopes and information, and there will be other educational activities throughout the evening.

The museum also offers a couple of events on Saturday, October 7. A 2 p.m. presentation called “21st Century Communities in Space: The Cultural Details in Living Away From Earth” will celebrate the 60th anniversary of Sputnik, and then look forward to the future when we’ve colonized the Moon and Mars and are creating communities in space. What sort of culture will be there?

Then at 5:30 p.m. join in on a reception, lecture, and book signing with space writer Leonard David. David’s book Mars: Our Future on the Red Planet (National Geographic, 2016) is a companion to the recent Mars miniseries produced by the National Geographic Channel. Tickets to this event are $25, $20 for museum members, and must be purchased online by October 3.

Haunted Night Sky

The Pierce College Science Dome brings back the popular planetarium show Haunted Night Sky on Saturdays during October. The show, geared for kids aged 3-12, guides viewers to use their imaginations to find creatures in the night sky, build a Frankenstein satellite, and take a tour of the Sea of Serpents on the Moon, the Witch’s Head nebula, and other spooky places in the universe. Showtimes are 12:30 p.m. and 2 p.m. each Saturday, and it runs about 45 minutes. Tickets are $6 for kids—adults are free—and are available in advance online.

Astronomy clubs

A quick rundown of the regional astronomy club meetings this week:

Mark your calendar

You can scout out future astronomy events by visiting our calendar page.


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Astro Biz: LUNA bars

Luna barsMany businesses, products, and places have names rooted in space and astronomy. We’re featuring one every Tuesday on Seattle Astronomy.

This week’s Astro Biz is LUNA bars. LUNA nutrition bars are a brand of Clif Bar and Company. LUNA was created in the late 1990s and was specifically aimed at providing nutrients often missing in women’s diets.

More info:

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Seattle Astronomy seeks your support through Patreon

Seattle Astronomy seeks your financial support in order to expand our astronomical journalism offerings. We’ve started a campaign on Patreon to achieve this goal.

PatreonPatreon is a platform built specifically with the needs of creative ventures in mind, and thus it’s a little different. Whereas with most crowdfunding solutions you might give a one-time-only contribution to a project, Patreon would be like a subscription to Seattle Astronomy—patrons pledge to give a set amount each month. As little as one dollar per month helps us reach our goals, but larger amounts get us there more quickly, and come with increasing perks!

Our goal in a nutshell is to raise enough funds to travel to cover space and astronomy stories outside of the Seattle area, both regionally and nationally. We’ve done occasional trips to Portland to cover interesting talks at Rose City Astronomers. We’d like to take that further afield to visit active clubs in Spokane, Eugene, Idaho Falls, Tri-Cities, and beyond. Ultimately we would like to raise enough to be able to cover national events such as meetings of the American Astronomical Society or the Astronomical League. These are loaded with interesting stories, but few of them get told outside of the meeting hall. We’ll be your eyes and ears looking for good stories, especially of the type of interest to the amateur astronomy community.

Please visit our Patreon page, check out the video, and sign up for your monthly contribution to Seattle Astronomy today. We appreciate your support!

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Calendar: What the heck is polarimetry?

The monthly gathering of Astronomy on Tap Seattle and a variety of star parties highlight this week’s calendar.

AOT

AOT Sept 27My Webster’s Ninth New Collegiate Dictionary defines polarimeter as “an instrument for determining the amount of polarization of light or the proportion of polarized light in a partially polarized ray.” I still don’t know what that means or why astronomers might be into polarimetry, but we’ll find out at 8 p.m. Wednesday, September 27 when Astronomy on Tap Seattle meets at Peddler Brewing Company in Ballard.

The guest speakers are both UW postdocs: Dr. Jamie Lomax will discuss her research using polarimetry to detect the almost-invisible material around stars, and Dr. Kim Bott will explain how she uses polarimetry to hunt for signs of habitable worlds.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington. The evening’s festivities include astronomy-themed trivia and fabulous prizes. It’s free, but buy beer. Bring your own chair to create custom front-row seating.

Star parties

Several star parties are on the calendar for the weekend. The Covington Community Park Star Party is scheduled for 9 p.m. Friday, September 29 at the park. The party is sponsored by Covington Parks and Recreation with support from the Seattle, Tacoma, and Boeing Employees astronomical societies.

The Seattle Astronomical Society plans its free monthly public star parties for 8 p.m. Saturday, September 30 at two locations: Green Lake in Seattle and Paramount Park in Shoreline.

Planetarium

The WSU Planetarium in Pullman offers a new program this weekend, “Astronomy 101.” The show runs at 7 p.m. Friday, September 29 and repeats at 5 p.m. Sunday, October 1. Tickets are $5 at the door, cash or check; no credit cards.

Mark your calendar

The Museum of Flight will observe Astronomy Night next Thursday, October 5 beginning at 5 p.m. Astronomy clubs from the area will be on hand with telescopes and information. It’s part of the museum’s free first Thursday offerings.

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