TRAPPIST-1 Planets Provide Clues To The Nature Of Habitable Worlds

TRAPPIST-1 is an ultra-cool red dwarf star that is slightly larger, but much more massive, than the planet Jupiter, located about 40 light-years from the Sun in the constellation Aquarius.

Among planetary systems, TRAPPIST-1 is of particular interest because seven planets have been detected orbiting this star, a larger number of planets than have been than detected in any other exoplanetary system. In addition, all of the TRAPPIST-1 planets are Earth-sized and terrestrial, making them an ideal focus of study for planet formation and potential habitability.

ASU scientists Cayman Unterborn, Steven Desch, and Alejandro Lorenzo of the School of Earth and Space Exploration, with Natalie Hinkel of Vanderbilt University, have been studying these planets for habitability, specifically related to water composition. Their findings have been recently published in Nature Astronomy.

Water on the TRAPPIST-1 Planets

The TRAPPIST-1 planets are curiously light. From their measured mass and volume, all of this system’s planets are less dense than rock. On many other, similarly low-density worlds, it is thought that this less-dense component consists of atmospheric gasses.

“But the TRAPPIST-1 planets are too small in mass to hold onto enough gas to make up the density deficit,” explains geoscientist Unterborn. “Even if they were able to hold onto the gas, the amount needed to make up the density deficit would make the planet much puffier than we see.”

So scientists studying this planetary system have determined that the low-density component must be something else that is abundant: water. This has been predicted before, and possibly even seen on larger planets like GJ1214b, so the interdisciplinary ASU-Vanderbilt team, composed of geoscientists and astrophysicists, set out to determine just how much water could be present on these Earth-sized planets and how and where the planets may have formed.

Calculating water amounts on TRAPPIST-1 planets

To determine the composition of the TRAPPIST-1 planets, the team used a unique software package, developed by Unterborn and Lorenzo, that uses state-of-the-art mineral physics calculators. The software, called ExoPlex, allowed the team to combine all of the available information about the TRAPPIST-1 system, including the chemical makeup of the star, rather than being limited to just the mass and radius of individual planets.

Much of the data used by the team to determine composition was collected from a dataset called the Hypatia Catalog, developed by contributing author Hinkel. This catalog merges data on the stellar abundances of stars near to our Sun, from over 150 literature sources, into a massive repository.

What they found through their analyses was that the relatively “dry” inner planets (labeled “b” and “c” on this image) were consistent with having less than 15 percent water by mass (for comparison, Earth is 0.02 percent water by mass). The outer planets (labeled “f” and “g” on this image) were consistent with having more than 50 percent water by mass. This equates to the water of hundreds of Earth-oceans. The masses of the TRAPPIST-1 planets continue to be refined, so these proportions must be considered estimates for now, but the general trends seem clear.

“What we are seeing for the first time are Earth-sized planets that have a lot of water or ice on them,” says ASU astrophysicist and contributing author, Steven Desch.

But the researchers also found that the ice-rich TRAPPIST-1 planets are much closer to their host star than the ice line. The “ice line” in any solar system, including TRAPPIST-1’s, is the distance from the star beyond which water exists as ice and can be accreted into a planet; inside the ice line water exists as vapor and will not be accreted. Through their analyses, the team determined that the TRAPPIST-1 planets must have formed much farther from their star, beyond the ice line, and migrated in to their current orbits close to the host star.

There are many clues that planets in this system and others have undergone substantial inward migration, but this study is the first to use composition to bolster the case for migration. What’s more, knowing which planets formed inside and outside of the ice line allowed the team to quantify for the first time how much migration took place.

Because stars like TRAPPIST-1 are brightest right after they form and gradually dim thereafter, the ice line tends to move in over time, like the boundary between dry ground and snow-covered ground around a dying campfire on a snowy night. The exact distances the planets migrated inward depends on when they formed. “The earlier the planets formed,” says Desch, “the further away from the star they needed to have formed to have so much ice.” But for reasonable assumptions about how long planets take to form, the TRAPPIST-1 planets must have migrated inward from at least twice as far away as they are now.

Too much of a good thing

Interestingly, while we think of water as vital for life, the TRAPPIST-1 planets may have too much water to support life.

“We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live,” explains Hinkel. “However, a planet that is a water world, or one that doesn’t have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life.”

Ultimately, this means that while M-dwarf stars, like TRAPPIST-1, are the most common stars in the universe (and while it’s likely that there are planets orbiting these stars), the huge amount of water they are likely to have makes them unfavorable for life to exist, especially enough life to create a detectable signal in the atmosphere that can be observed. “It’s a classic scenario of ‘too much of a good thing,'” says Hinkel.

So, while we’re unlikely to find evidence of life on the TRAPPIST-1 planets, through this research we may gain a better understanding of how icy planets form and what kinds of stars and planets we should be looking for in our continued search for life.

Jacksonville Tornado Upgraded To EF-3 With 140 Mph Winds, NWS Says

Damage is widespread from severe storms, large hail and tornadoes that raked across Alabama on Monday.

And at least nine tornado touchdowns have been confirmed as of Tuesday — including an EF-3 twister that did considerable damage in Jacksonville. More confirmations are likely over the next few days. Homeowners should take provisions to protect their property. There are companies that can assess hail damage Denver, or wherever it is that you are needing the service in order to make repairs that are needed as a result of storm damage.

The National Weather Service offices in both Huntsville and Birmingham sent out multiple storm survey teams on Tuesday to look at the damage and determine if tornadoes caused it — and how strong those tornadoes were.

The weather service in Huntsville said that preliminary data now confirm at least six separate touchdowns in north Alabama — in or near Cedar Creek Lake, Falkville, Albertville, northern Madison, Ardmore and Russellville.

The Ardmore storm in Limestone County has been given a preliminary rating of EF-2, the weather service said. A preliminary EF-1 rating has been assigned to the storms in Russellville, Madison and Cedar Creek Lake.

After initially giving the Jacksonville storm a preliminary rating of EF-2 earlier Tuesday, the weather service in Birmingham upgraded it to an EF-3 with winds of around 140 mph. The weather service said the upgrade was based on structural damage around Jacksonville State University.

It is the first EF-3 tornado to hit Alabama since Nov. 30, 2016.

The weather service said that storm cycled and produced three tornadoes from Asheville to Southside to Jacksonville.

The survey team is still assessing that storm’s track, which crossed over into Georgia. Because of its length, the survey won’t be wrapped up today, the weather service said.

Surveyors will also look at what could be another track south of the city.

Survey teams have also found another area to take a look at in Cherokee County, the weather service said.

The weather service was flooded with reports of hail and wind damage during the afternoon and evening hours on Monday.

Several tornadoes have also been reported, and the survey teams will continue to determine when and where touchdowns occurred and how strong those storms were.

The weather service said it’s likely the surveys will take more than one day to complete. Updates will be issued on the teams’ progress.

How big was the hail?

Early indications are that there was considerable hail damage across parts of Alabama on Monday. Several residents will have to use the service of hail damage roofers once this weather has passed, due to the hail’s intensity. The hail has significantly damaged some homes and homeowners should check their roofs as soon as it’s safe to. If unsure of the condition of the roof, homeowners should not leave alone and contact a company such as Division Kangaroof with experience in roof inspections to determine if repair or replacement is required.

Large hail was reported in many areas in north and eastern Alabama.

Possibly the largest was hailstones the size of baseballs reported by a storm chaser in the Cullman area.

Mars’ Oceans Formed Early, Possibly Aided By Massive Volcanic Eruptions

A new scenario seeking to explain how Mars’ putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million years earlier and were not as deep as once thought.

The proposal by geophysicists at the University of California, Berkeley, links the existence of oceans early in Mars history to the rise of the solar system’s largest volcanic system, Tharsis, and highlights the key role played by global warming in allowing liquid water to exist on Mars.

“Volcanoes may be important in creating the conditions for Mars to be wet,” said Michael Manga, a UC Berkeley professor of earth and planetary science and senior author of a paper appearing in Nature this week and posted online March 19.

Those claiming that Mars never had oceans of liquid water often point to the fact that estimates of the size of the oceans don’t jibe with estimates of how much water could be hidden today as permafrost underground and how much could have escaped into space. These are the main options, given that the polar ice caps don’t contain enough water to fill an ocean.

The new model proposes that the oceans formed before or at the same time as Mars’ largest volcanic feature, Tharsis, instead of after Tharsis formed 3.7 billion years ago. Because Tharsis was smaller at that time, it did not distort the planet as much as it did later, in particular the plains that cover most of the northern hemisphere and are the presumed ancient seabed. The absence of crustal deformation from Tharsis means the seas would have been shallower, holding about half the water of earlier estimates.

“The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later,” Manga said. “We’re saying that the oceans predate and accompany the lava outpourings that made Tharsis.”

It’s likely, he added, that Tharsis spewed gases into the atmosphere that created a global warming or greenhouse effect that allowed liquid water to exist on the planet, and also that volcanic eruptions created channels that allowed underground water to reach the surface and fill the northern plains.

Following the shorelines

The model also counters another argument against oceans: that the proposed shorelines are very irregular, varying in height by as much as a kilometer, when they should be level, like shorelines on Earth.

This irregularity could be explained if the first ocean, called Arabia, started forming about 4 billion years ago and existed, if intermittently, during as much as the first 20 percent of Tharsis’s growth. The growing volcano would have depressed the land and deformed the shoreline over time, which could explain the irregular heights of the Arabia shoreline.

Similarly, the irregular shoreline of a subsequent ocean, called Deuteronilus, could be explained if it formed during the last 17 percent of Tharsis’s growth, about 3.6 billion years ago.

“These shorelines could have been emplaced by a large body of liquid water that existed before and during the emplacement of Tharsis, instead of afterwards,” said first author Robert Citron, a UC Berkeley graduate student. Citron will present a paper about the new analysis on March 20 at the annual Lunar and Planetary Science conference in Texas.

Tharsis, now a 5,000-kilometer-wide eruptive complex, contains some of the biggest volcanoes in the solar system and dominates the topography of Mars. Earth, twice the diameter and 10 times more massive than Mars, has no equivalent dominating feature. Tharsis’s bulk creates a bulge on the opposite side of the planet and a depression halfway between. This explains why estimates of the volume of water the northern plains could hold based on today’s topography are twice what the new study estimates based on the topography 4 billion years ago.

New hypothesis supplants old

Manga, who models the internal heat flow of Mars, such as the rising plumes of molten rock that erupt into volcanoes at the surface, tried to explain the irregular shorelines of the plains of Mars 11 years ago with another theory. He and former graduate student Taylor Perron suggested that Tharsis, which was then thought to have originated at far northern latitudes, was so massive that it caused the spin axis of Mars to move several thousand miles south, throwing off the shorelines.

Since then, however, others have shown that Tharsis originated only about 20 degrees above the equator, nixing that theory. But Manga and Citron came up with another idea, that the shorelines could have been etched as Tharsis was growing, not afterward. The new theory also can account for the cutting of valley networks by flowing water at around the same time.

“This is a hypothesis,” Manga emphasized. “But scientists can do more precise dating of Tharsis and the shorelines to see if it holds up.”

NASA’s next Mars lander, the InSight mission (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport), could help answer the question. Scheduled for launch in May, it will place a seismometer on the surface to probe the interior and perhaps find frozen remnants of that ancient ocean, or even liquid water.

Large Storm System To Bring Severe Weather To South; East Coast Expecting Snow Soon

A large storm system is moving through the Great Plains on Monday morning bringing unsettled weather from the Dakotas all the way to the southeastern United States.

Yesterday, more than three dozen damaging storm reports were made, most of them in east-central Texas where hail was larger than a baseball. There were also two reported tornadoes in the Texas panhandle and winds of 60 mph or greater in eastern Texas.

On the northern side of the storm, heavy snow fell around Denver, with anywhere from 5 to 10 inches overnight in the metro area.

The storm system is moving east Monday, and is now stretching from the Northern Plains to the Gulf Coast. To the north, snow is falling in the Dakotas while tornado warnings have been issued for part of the Florida panhandle.

The storm system will move further east Monday afternoon, and will pick up moisture from the Gulf of Mexico. Severe storms will break out from Jacksonville, Florida, to Atlanta; Birmingham, Alabama; and into Nashville, Tennessee.

The biggest threat will be huge damaging hail, tornadoes and wind. Flash flooding is also possible.

The biggest threat for tornadoes will be from Nashville to Birmingham and just west of Atlanta this afternoon and evening.

Developing in the East

As the storm moves east on Tuesday, a coastal low will try to develop in the southern Mid-Atlantic states producing a first wave of rain and snow from Washington, D.C. north into Pennsylvania and west into West Virginia. Several inches of snow is possible just west of Washington, D.C.

By Tuesday night into Wednesday, as the coastal low strengthens, it will produce a second wave of rain and snow, spreading along the I-95 corridor from Washington, D.C. into New York City and Boston.

Models are still not very confident where the low will form and how much snow or rain will fall in the heavily populated I-95 corridor. If major cities get precipitation, it would be mostly be on Wednesday.

The American model isn’t showing much snow for the major cities — maybe a dusting to 1 to 2 inches on Wednesday.

The European model has a different forecast with heavy snow accumulations for the major Northeast cities, but ABC News meteorologists predict the model is probably overdoing these amounts.

The short-term American model is showing the storm missing Washington, D.C., Philadelphia and New York City, with maybe some snow accumulations along the Mid-Atlantic coast and into Cape Cod.

It could go either way, but confidence is growing that some sort of storm system will form along the East Coast.

Volcano Watch: Kilauea Volcano’s Summit Eruption Is Now A Decade Old

A little more than 10 years ago, conditions around Kilauea Volcano’s summit were much different than today. The caldera floor was open to the public, and the air above it was normally clear. Halema‘uma‘u was an impressive sight, but peacefully in repose.

That quiet phase at Kilauea’s summit ended abruptly in 2008, ushering in a new era of lava lake activity that continues today.

Let’s review the past decade of this summit eruption.

After several months of increased seismic tremor and gas emissions, there was a small explosion in Halema‘uma‘u on March 19, 2008. The explosion marked the opening of a new crater, informally called the “Overlook crater.” During the remainder of 2008, several more explosions deposited spatter around Halema‘uma‘u, and the Overlook crater enlarged through collapses of its rim.

During 2009, small lava lakes were sometimes active deep within the Overlook crater. But since early 2010, the lava lake has been continuously present, steadily growing and rising higher.

The rise was interrupted March 5, 2011, when the lava lake briefly drained away because of the Kamoamoa eruption on Kilauea’s East Rift Zone.

The lava lake stabilized in 2012, rose to a higher level in 2013 and remained stable in 2014 and early 2015. In April 2015, the lava lake rose abruptly and briefly overflowed, spilling lava onto the floor of Halema‘uma‘u. High lake levels in 2016 allowed lava to be frequently observed from public viewing areas in Hawaii Volcanoes National Park, but a gradual drop in 2017 has made direct viewing of the lake less common during the past year.

The lava lake activity in 2018 is similar to that during the previous several years — relatively steady — and there are no signs that the summit eruption is slowing down.

Halema‘uma‘u now hosts one of the two largest lava lakes on Earth. It is likely the largest, but this cannot be said with complete certainty, as regular measurements are not available from the closest contender — Nyiragongo volcano in the Democratic Republic of the Congo.

Most persistent lava lakes are difficult to access, either because of geographic location (for example, Erebus in Antarctica) or political instability (for example, Nyiragongo). The size and accessibility of the Halema‘uma‘u lava lake, as well as the existing network of monitoring instruments, make it one of the premier locations to study lava lake behavior.

USGS Hawaiian Volcano Observatory scientists, along with collaborators from other institutions, are engaged in research to understand how the lava lake works and what it can tell us about the behavior and hazards of Kilauea.

For instance, we learned that the lake rises and falls in concert with changes in summit ground tilt. This tells us that the lake responds to the pressure of the magma chamber, so the lake level can be used like a pressure gauge.

The lake also fluctuates in concert with the lava pond at Pu‘u ‘O‘o on Kilauea’s East Rift Zone, illustrating the hydraulic connection between the two eruption sites. Lava chemistry at the two sites also is similar, adding further evidence of a close connection.

Another important finding deals with the nature of small explosions that occur at the lava lake from time to time.

HVO webcams revealed that the explosions are triggered by rockfalls from the Overlook crater rim impacting the lake surface. This observation is further evidence that the lava lake is very gassy, akin to lava foam. Rocks falling into this gas-rich, frothy lava triggers violent releases of gas that send spatter flying.

While the summit eruption has benefited science, it comes with many challenges, including persistent volcanic air pollution (vog) resulting from elevated sulfur dioxide gas emissions from the lava lake. Vog impacts the entire state at times, but the Ka‘u and Kona districts on the Island of Hawaii have been particularly hard hit.

Kilauea has a history of long-lasting summit eruptions, but it remains to be seen if the current eruption will go on for another decade. The past few years of stable activity suggest the summit lava lake is likely to continue into the near future.

However long it lasts, HVO will continue to study this awe-inspiring, unique feature to discover what more it can reveal about the volcano.

Volcano activity updates

This past week, Kilauea Volcano’s summit lava lake level fluctuated with summit inflation and deflation, ranging about 30.5-40.5 m (100-133 ft) below the vent rim. On the East Rift Zone, the 61g lava flow remained active downslope of Pu‘u ‘O‘o, with scattered breakouts on the upper part of the flow field and on Pulama pali, but no ocean entry. The 61g flows do not pose an immediate threat to nearby communities.

Mauna Loa is not erupting. Rates of deformation and seismicity have not changed significantly in the past week, persisting at above-long-term background levels. Sixteen microearthquakes (magnitudes less than 2) were located beneath the summit caldera, upper Southwest Rift Zone and western flank of the volcano at depths of 0-5 km (0-3 mi). GPS and InSAR measurements continue to show slow deformation related to inflation of a magma reservoir beneath the summit and upper Southwest Rift Zone. No significant changes in volcanic gas emissions were measured.

No earthquakes were reported felt in the Hawaiian Islands this past week.

Volcanic Activity Threatens Families Again On Ambae Island In Vanuatu

Volcanic activity on Vanuatu’s Ambae Island has picked up again over the last few days, with fresh ash fall reported across the island’s west and south.

Communities in the western and southern parts of Ambae are suffering badly from thick periodic ash fall which threaten their health, animals and vegetation.

The entire island was evacuated late last year when the volcano at the island’s centre erupted, blanketing the island in ash, suffocating crops and contaminating water sources.

The only population returned to their homes when the eruption settled down after a month, but on Sunday night the volcano’s alert level was raised from level 2 to 3, a “state of minor eruption.”

The Geohazards Department’s Melinda Aru said the volcano was showing increased activity and an exclusion zone had been extended to three km around the crater lake.

“We’ve got a few reports coming from Ambae concerning ash fall on the west, southwest and northwest as of last week until Sunday. We still have reports from Ambae concerning ash fall.”

Melinda Aru said the chance of the eruption increasing to the level seen in October last year was highly unlikely.

Reports on the Vanuatu Daily Post website on Monday said that people may need to shelter livestock and water tanks as the Lombenben volcano continues to emit ash.

The Vanuatu Meteorology and Geo-hazards Department still grades the Ambae volcano at major unrest stage.

Destruction caused by the ash fall in affected areas is described as literally similar to a cyclone wiping out trees and crops.

Its weight caused plants and crops in the gardens like banana, cassava and cabbages to collapse.

Destruction done by volcanic ash on people, plants and crops depend largely on its thickness. Though it may causes health problems to livestock and human such as skin irritation and eye problem, volcanic ash can make the soil fertile.

Responsible authorities have warned that everyone, particularly children should be protected from the volcano’s ash and poisonous gases that poses a health risk.

The Vanuatu Red Cross Society (RCS) said it was working to establish a sub-branch in west Ambae to support communities during disasters.

Madagascar Hit By Another Tropical Cyclone

Tropical Cyclone Eliakim has battered Madagascar with strong winds and torrential rain.

The storm made landfall on the peninsula of Masoala in northeastern Madagascar and tracked southwards along the coast.

Strong winds battered the island and torrential rain fell on already-saturated land, triggering landslides and flooding.

The cyclone comes less than two weeks after Dumazile grazed the east coast of the island nation.

Both storms hit Toamasina, Madagascar’s second largest city. Images on social media showed widespread flooding with roads and homes inundated.

According to local media, at least one person has been killed by Eliakim and many more have been injured.

The storm is now weakening as it moves southeast, away from Madagascar.