ChUMPs, Snowball Earth, and the Cambrian Explosion

Posted by admin on October 5, 2015
Posted in: BSU Geoscience Seminars. Tagged: , , .
Artist's depiction of ancient snowball Earth. From http://ichef.bbci.co.uk/naturelibrary/images/ic/credit/640x395/s/sn/snowball_earth/snowball_earth_1.jpg.

Artist’s depiction of ancient snowball Earth. From http://ichef.bbci.co.uk/naturelibrary/images/ic/credit/640×395/s/sn/snowball_earth/snowball_earth_1.jpg.

I sat in on a fascinating seminar today in the Geosciences Dept. given by Prof. Carol Dehler of Utah State University about statigraphic and isotopic evidence for a snowball Earth event.

Over its 4.5 billion year history, the Earth has probably experienced at least one, maybe more, severe glaciation events, during which ice covered more or less the whole Earth’s surface.

These events were probably very challenging for ancient Earth life, and some of the best documented events occurred at the end of the Neoproterozoic, about 540 million years ago, probably driving mass extinctions and possibly kicking off the Cambrian explosion in animal life.

In her presentation today, Prof. Dehler discussed her extensive field and laboratory studies of statigraphic deposits in the western US, laid down about this time in Earth’s history, deposits she calls ChUMPs.

While the ChUMP layers were building up, the Earth was going through dramatic geological and climatic variations. The ancient supercontinent of Rodinia was breaking up, and Dehler can see evidence of volcanism that accompanied this rifting as huge excursions in carbon isotopes locked up in the ChUMP deposits.

The carbon dioxide injected by these large eruptions probably also drove climate change, raising global temperatures, which caused rapid weathering of rocks that locked up the excess carbon dioxide in the rocks.

With so much CO2 sucked out the atmosphere, it’s possible the Earth then underwent rapid cooling, and this is what could have driven Earth into a snowball state during the Neoproterozoic.

However, the story told by the rocks and their isotopic compositions is complicated, and it’s not entirely clear whether the enhanced volcanism preceded the snowball Earth event: The ages attributed to the rocks still have uncertainties that are too large to be sure.

In any case, Dehler presented a compelling, complex story about the Earth’s ancient history, meticulously pieced together, one mineral grain at a time.

Flowing Water (and Life?) on Mars

Posted by admin on October 3, 2015
Posted in: BSU Journal Club.

Warm_Season_Flows_on_Slope_in_Horowitz_Crater_(animated)First, I would like to thank Michael Blanchard and Rena Drennon for their generous support of our PonyUp Campaign at Boise State.

At journal club this week, we had to talk about the recent confirmation of flowing water on the surface of Mars. How did scientists confirm that water is flowing on Mars? They studied a well-known martian phenomenon, recurring slope lineae (RSL).

These lanes of darkened martian surface occur seasonally, usually on the slopes of craters facing the Sun, and have been observed on Mars for a few years. Their seasonal occurrence on Sun-facing slopes pointed to the possibility that they result from flowing water, but since flowing water on Mars could be such a huge discovery, scientists have been very cautious about their origins; hence the obscure name.

In the recent paper, Ojha and colleagues analyzed high-spatial resolution observations of Mars from the HiRISE camera to carefully localize the flows on Mars’ surface. They then analyzed infrared observations from HiRISE’s sister instrument CRISM to look for spectral evidence of salts dissolved in water.

The salts they looked for aren’t like table salt but instead consist primarily of perchlorates. These chemicals can be toxic for us, but they are well-documented on Mars. Ohja and colleagues showed that the lineae exhibit spectral features consistent with dissolution of perchlorate salts.

These salts are known to significantly lower the freezing point of water, so they could easily keep water liquid, despite Mars’ cold temperatures. Eventually, even this briny water sublimates at Mars’ low surface pressures, and the spectral features found by Ohja and colleagues fade as the linaea fade, presumably as the water evaporates on the surface.

Why is this discovery so exciting? It points to the very real possibility that there is microbial life on Mars in liquid water deposits deep beneath the surface.

Early in the solar system’s history, the life-giving soup of chemicals that rained down in meteorites on Earth probably fell on Mars. Conditions on early Mars could have been similar to Earths’, so life could very likely have arisen. Whether life still exists on Mars may just be a question of whether it could escape to subsurface oases bearing liquid water, whose existence is strongly suggested by this new discovery. It may be only a matter of a few years before we find life on Mars.

In attendance at journal club this week were Jennifer Briggs, Karan Davis, Hari Goppalakrishnan, Tyler Gordon, and Emily Jensen.

The Super Blood Moon at Boise State

Posted by admin on September 28, 2015
Posted in: Public Outreach. Tagged: , , .
The Super Blood Moon from Boise State's campus.

The Super Blood Moon from Boise State’s campus.

We had a HUGE event last night on campus at Boise State. No precise estimates, but I’d guess we had a few hundred people show up for the eclipse, as well as Lacey Darrow of Channel 6. It was an amazing experience. Thanks to everyone for attending.

Our Pony Up Campaign made its initial goal on Saturday morning, only halfway through the campaign. So we’re trying for a stretch goal of $2,000 to pay for wifi at our observatory. Wifi will significantly enhance our public outreach events and instructional efforts. It would also allow us to more easily stream live footage from our telescopes during public events. The campaign will run until Oct. 14.

And thanks to Lynne Barnes for supporting us.

2015 Total Lunar Eclipse

Posted by admin on September 25, 2015
Posted in: Public Outreach. Tagged: , , .

Lunar_eclipse_April_15_2014_California_Alfredo_Garcia_Jr1Join the Boise State Physics and Astronomy Club on the top of the Brady State Garage on Boise State’s Campus to view the last total lunar eclipse until 2018.

The eclipse occurs on Sunday, Sep 27, and the viewing event runs from 7pm till midnight. The Boise State Physics Dept. will provide telescopes, and visitors are encouraged to bring chairs. Contact Prof. Brian Jackson with questions.

And thanks to Pam Robbins, Susan Steffes-Ferri, Memo Cordova, & Mike Kennedy for supporting our PonyUp Campaign to bring back the Boise State Observatory.

Screen Shot 2015-09-21 at 10.29.37 AM

We’re Halfway There!

Posted by admin on September 18, 2015
Posted in: Public Outreach, Uncategorized. Tagged: , .

Friends,
As of this morning, we are halfway to our goal of $8,000. And in only the first week. Thanks very much to all those who have given, including Barbara Hatcher and Jim Ogle.

Please talk to your friends and family and share your enthusiasm for our project and for astronomy. Your support means a lot to me personally and will help us usher in an amazing resource for astronomy education here in Boise.

Ask an Astronomer at Flying M Coffee

Posted by admin on September 16, 2015
Posted in: Brian's Presentations, Public Outreach. Tagged: , , .

CO_CGKlUkAAPKhCHad a great time last night at Flying M Coffee in Nampa. I gave a short talk about my research and recent developments in exoplanet astronomy.

Then I opened the floor up for questions — the best part of the night. Lots of really great questions about alien life, what exoplanets are like, when will we find life.

One question that stood out for me was asked by a young woman about how we study the composition of exoplanet atmospheres. I talked about the promise of the James Webb Space Telescope to measure transits in different colors. And there was a moment of genuine awe and surprise I could see on her face. It was really great.

As of this writing, our campaign has broken $1600 — very exciting. Thanks to Cindy Hall and April and Seth Masarik for their support.

Day One of the PonyUp Campaign

Posted by admin on September 15, 2015
Posted in: Public Outreach. Tagged: , , .

Screen Shot 2015-09-15 at 11.31.24 AMAfter only one day of our PonyUp Campaign to Bring Back the Boise State Observatory, we’re already more than 15% there.

We’ve had some press on the project from several sources, including the local Fox 9 channel. Very exciting.

Special thanks to our donors Christian Lybrook, Ryan Lujan, LaVona Andrew, Marlene & Jim O’Tousa, Rick and Valerie Flores, and Charles Jewell.

Discovery of a young Jovian planet, 51 Eri b

Posted by admin on September 11, 2015
Posted in: BSU Journal Club. Tagged: , .
Image of 51 Eri b (indicated by arrow) in the near-infrared, 1.65 microns.

Image of 51 Eri b (indicated by arrow) in the near-infrared, 1.65 microns.

A little behind the times on this one, but we finally managed to discuss the exciting discovery of a young, Jupiter-like planet in a Jupiter-like orbit by the Gemini Planet Imager (GPI) team at journal club today.

Using high-precision optical instrumentation and some sophisticated data processing to block out the host star’s glare, the team was able to directly image the planet 51 Eri b in infrared wavelengths.

No mean feat, given that the star is more than a million times brighter than the planet and is only one ten-thousandth of a degree away in the sky. This is a little like trying to see the glow of a firefly in the end zone against the glare of a football stadium light from the 50 yard line when the two are separated by the width of a human hair*.

51 Eri b is only 20 million years old, so it’s much hotter and glows much more brightly than our own Jupiter-like planets, making it easier to see. Jupiter-like planets tend to cool in a more-or-less well-behaved way that depends partially on their masses — bigger planets start out hotter. However, the planet is much cooler than predicted by some planet formation models, which provides strong constraints on the ways in which gas giants form.

So using 51 Eri b’s estimated temperature, 700 K (400 C) and age, Macintosh et al. put its mass somewhere between 2 and 12 Jupiter masses — solidly in the planet category.

The GPI observations also show us the planet has methane and water in its atmosphere. In fact, the methane detection for this planet is the most prominent so far seen for an exoplanet, according to Macintosh.

The GPI instrument is positioned to find many more planets like this one in the coming years, so expect lots of exciting results in the next few years.

Today’s journal club attendees included Jennifer Briggs, Hari Gopalakrishnan, Tyler Gordon, and Emily Jensen.

*Macintosh et al. estimate 51 Eri b’s luminosity is about 1 millionth that of our Sun. Wikipedia indicates the star 51 Eri is about 5 times brighter than our Sun. I had a lot of trouble finding the luminosity of a firefly — this page is the best I could do, and it estimates that one firefly emits about 2 mW. Stadium lights look to emit about 1,000 W, so that gives my factor of one million in luminosity.

51 Eri b has a projected separation from its host star of 13 AU, and the star is about 96 light years away, giving an angular separation of about 2 microradians. A human hair is about 100 microns across, so it would subtend 2 microradians from a distance of about 50 yards.

IAU Day 5 — Transit-Timing Variations, Tides, and Binaries

Posted by admin on August 16, 2015
Posted in: Meetings. Tagged: , , , , .

IMG_2366Final day of the IAU meeting  general assembly found me in talks about transit-timing variations, tidal interactions, and planets in binary star systems.

The first session focused on the impressive results from transit-timing variation (TTV) studies. Since detecting and modeling TTVs is very data-intensive, the talks explored the data science aspects of TTV analysis. Ben Montet‘s talk, for example, looked at how hard it can be to detect transits in the first place, much less measure their period variations. To estimate uncertainties on their variations, he advocated using importance sampling and generating thoroughly explored prior distributions.

The next session looked at tidal interactions and planets in binary star systems. Smadar Naoz talked about her work on Kozai oscillations and how she showed that Kozai had made some fairly specific assumptions that limited his famous dynamical analysis in important ways. Her improved analysis shows that, contrary to the original results, the Kozai mechanism can actually produce planets on retrograde orbits and so can help explain the growing number of such retrograde planets.

I also spoke in the second session about Roche lobe overflow in short-period gaseous exoplanets, and I’ve posted my presentation below.

So, all in all, a really brilliant conferences in an inspiring locale. Mahalo, Hawaii.

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Tidal Decay and Disruption of Gaseous Exoplanets