Zwicky Transient Facility sees first light

Astronomers announced today that the Zwicky Transient Facility at the Palomar Observatory in California has seen first light, and will begin full operations in 2018.

When fully operational in 2018, the ZTF will scan almost the entire northern sky every night. Based at the Palomar Observatory in southern California and operated by Caltech, the ZTF’s goal is to use these nightly images to identify “transient” objects that vary between observations — identifying events ranging from supernovae millions of light years away to near-Earth asteroids.
an image of stars and the night sky

In 2016, the UW Department of Astronomy formally joined the ZTF team and will help develop new methods to identify the most “interesting” of the millions of changes in the sky — including new objects — that the ZTF will detect each night and alert scientists. That way, these high-priority transient objects can be followed up in detail by larger telescopes, including the UW’s share of the Apache Point Observatory 3.5-meter telescope.

By producing new high resolution images of the entire northern sky every night, this telescope instrument is going to discover gobs of new transients, from supernovae to binaries to novae to things we haven’t even seen before.

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Physicists once again fail to detect dark matter

The uncertainty of science: The most sensitive detector yet created by physicists has once again failed to detect dark matter, casting strong doubt on all present theories for its existence.

The latest results from an experiment called XENON1T at the Gran Sasso National Laboratory in Italy, published on 30 October, continue a dry spell stretching back 30 years in the quest to nab dark-matter particles. An attempt by a Chinese team to detect the elusive stuff, the results of which were published on the same day, also came up empty-handed. Ongoing attempts by space-based telescopes, as well as at CERN, the European particle-physics laboratory near Geneva, Switzerland, have also not spotted any hints of dark-matter particles.

The findings have left researchers struggling for answers. “We do not understand how the Universe works at a deeper and more profound level than most of us care to admit,” says Stacy McGaugh, an astrophysicist at Case Western Reserve University in Cleveland, Ohio.

The process here has been a good demonstration of the scientific method. Observers detect a phenomenon that does not make sense, which in this case was that the outer regions of galaxies rotate so fast that they should fly apart. Theorists then come up with a hypothesis to explain the phenomenon, which here was dark matter, subatomic particles that have weight but do not generally interact with the rest of the universe except by their mass, which acts to hold the galaxies together. Observers than try to prove the hypothesis by finding these theorized particles.

When the particles are not found, the theorists begin to rethink their theories. Maybe dark matter does not exist. Maybe (as is mentioned near the end of the article) a rethinking of the nature of gravity itself might be necessary. Or possibly the unseen matter is not subatomic, but ordinary matter not yet detected.

If only the climate field would apply this basic scientific method to its work. There, scientists found that carbon dioxide is increasing in the atmosphere. Some theorists posited an hypothesis that said that this increase might cause the climate to warm, and created numerous (almost a hundred) models to predict this warming. After more than thirty years, however, none of those models has successfully worked. The climate has not warmed as predicted, which suggests the hypothesis is flawed, and needs rethinking. Sadly, the leaders in the climate field refuse to do this rethinking. Instead, they appear willing to adjust and change their data to make it fit, sometimes in ways that are downright fraudulent.

This is not how science is done, and it is doing a terrible disservice to both science and society in general.

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First infrared image of a red giant star with a mass of the sun

 W Hydrae

Astronomers have used the ALMA array in Chile to take the first infrared image of a red giant star that has a mass similar to the Sun.

The dotted ring in the the image, cropped to post here, shows the Earth’s orbit. The star is farther along in its evolution than the Sun, and has expanded as it begins to use up its nuclear fuel.

The observations have also surprised the scientists. The presence of an unexpectedly compact and bright spot provides evidence that the star has surprisingly hot gas in a layer above the star’s surface: a chromosphere. “Our measurements of the bright spot suggest there are powerful shock waves in the star’s atmosphere that reach higher temperatures than are predicted by current theoretical models for AGB stars,” says Theo Khouri, astronomer at Chalmers and member of the team.

An alternative possibility is at least as surprising: that the star was undergoing a giant flare when the observations were made.

The handful of infrared images that astronomers have taken so far of several red giant stars indicates that these stars no longer look like the Sun, with a clear and precise spherical shape, but are puffed up almost like a cloud, with many uneven layers and complex extensions produced by their chaotic nature. This image of W Hydrae reinforces this impression.

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Astronomers find Kuiper Belt-like ring around Proxima Centauri

Worlds without end: Astronomers have found a dusty ring 1 to 4 astronomical units from the nearest star, Proxima Centauri.

Because Proxima Centauri is a smaller, dimmer star, its system is more compact. Proxima b [the star’s known exoplanet] circles the star at 0.05 astronomical units (a.u., the average distance between Earth and the Sun) — for reference, Mercury orbits the Sun at 0.39 a.u. The dusty ring lies well beyond that, extending from 1 to 4 a.u.

The Proxima ring is similar in some ways to the Kuiper Belt, a cold, dusty belt in the far reaches of our solar system (beyond 40 a.u.) that contains a fraction of Earth’s mass. While the Kuiper belt is well known for larger members such as Pluto and Eris, it also contains fine grains, ground down through collisions over billions of years. The dust ALMA observed around Proxima Centauri is composed of similar small grains. The average temperature and total mass of the Proxima ring is also about the same as our Kuiper Belt.

Because the ring here much closer to the star than our Kuiper Belt, the material is much more densely packed. Moreover, the presence of both a ring and an exoplanet suggests more planets might remain undiscovered there, increasing the chances that this star could have a solar system very worthwhile exploring.

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Fifth mirror for Giant Magellan Telescope has been cast

The fifth mirror, out of seven, for Giant Magellan Telescope (GMT) has been cast by the University of Arizona mirror lab.

With its casting this weekend, the fifth GMT mirror joins three additional GMT mirrors at various stages of production in the Mirror Lab. Polishing of mirror 2’s front surface is well underway; coarse grinding will begin on the front of the third mirror shortly and mirror number 4, the central mirror, will soon be ready for coarse grinding following mirror 3. The first GMT mirror was completed several years ago and was moved to a storage location in Tucson this September, awaiting the next stage of its journey to Chile. The glass for mirror 6 has been delivered to Tucson and mirror seven’s glass is on order from the Ohara factory in Japan.

In time, the giant mirrors will be transported to GMT’s future home in the Chilean Andes at the Carnegie Institution for Science’s Las Campanas Observatory. This site is known for being one of the best astronomical sites on the planet with its clear, dark skies and stable airflow producing exceptionally sharp images. GMTO has broken ground in Chile and has developed the infrastructure on the site needed to support construction activities.

If all goes right, GMT will begin its science work using 4 mirrors in 2020, with the use of all 7 mirrors beginning in 2022. This will be several years before the larger Thirty Meter Telescope and the European Extremely Large Telescope.

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NASA wants private company to take over Spitzer Space Telescope

NASA has issued a request for proposals from private companies or organizations to take over the operation of the Spitzer Space Telescope after 2019.

NASA’s current plans call for operating Spitzer through March of 2019 to perform preparatory observations for the James Webb Space Telescope. That schedule was based on plans for a fall 2018 launch of JWST, which has since been delayed to the spring of 2019. Under that plan, NASA would close out the Spitzer mission by fiscal year 2020. That plan was intended to save NASA the cost of running Spitzer, which is currently $14 million a year. The spacecraft itself, though, remains in good condition and could operating well beyond NASA’s current plan.

“The observatory and the IRAC instrument are in excellent health. We don’t have really any issues with the hardware,” said Lisa Storrie-Lombardi, Spitzer project manager, in a presentation to the committee Oct. 18. IRAC is the Infrared Array Camera, an instrument that continues operations at its two shortest wavelengths long after the spacecraft exhausted the supply of liquid helium coolant.

The spacecraft’s only consumable is nitrogen gas used for the spacecraft’s thrusters, and Storrie-Lombardi said the spacecraft still had half its supply of nitrogen 14 years after launch.

The way a private organization could make money on this is to charge astronomers and research projects for observation time. This could work, since there is usually a greater demand for research time than available observatories.

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New exoplanet defies accepted theories of planet formation

The uncertainty of science: A newly discovered exoplanet, the size of Jupiter and orbiting a star half the size of the Sun, should not exist based on all the presently favored theories of planet formation.

New research, led by Dr Daniel Bayliss and Professor Peter Wheatley from the University of Warwick’s Astronomy and Astrophysics Group, has identified the unusual planet NGTS-1b – the largest planet compared to the size of its companion star ever discovered in the universe.

NGTS-1b is a gas giant six hundred light years away, the size of Jupiter, and orbits a small star with a radius and mass half that of our sun.

Its existence challenges theories of planet formation which state that a planet of this size could not be formed by such a small star. According to these theories, small stars can readily form rocky planets but do not gather enough material together to form Jupiter-sized planets. The planet is a hot Jupiter, at least as large as the Jupiter in our solar system, but with around 20% less mass. It is very close to its star – just 3% of the distance between Earth and the Sun – and orbits the star every 2.6 days, meaning a year on NGTS-1b lasts two and a half days.

No one should be surprised by this. While the present theories of planet formation are useful and necessary, giving scientists a rough framework for studying exoplanets, they should not be taken too seriously. We simply do not yet have enough information about how stars, solar systems, and planets form.

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Astronomers find 20 more exoplanet candidates in Kepler archive

Worlds without end: Astronomers reviewing the Kepler archive have found 20 more exoplanet candidates, including one that has a mass about 97 percent of the Earth with an orbit 395 days long circling a star like the Sun.

The planet would be colder than Earth, as its star is slightly cooler than the Sun, and its orbit is slightly farther away. Nonetheless, this is an amazing twin, and would certainly be a prime target when interstellar travel becomes routine.

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The first large object identified coming from interstellar space

Astronomers think they have spotted the first large object to come from beyond the solar system.

Based on its apparent brightness, dynamicist Bill Gray calculates that it would have a diameter of about 160 meters (525 feet) if it were a rock with a surface reflectivity of 10%. “It went past the Sun really fast,” Gray notes, “and may not have had time to heat up enough to break apart.”

Now it’s headed out of the solar system, never to return. It passed closest to Earth on October 14th at a distance of about 24,000,000 km (15,000,000 miles), and astronomers worldwide have been tracking it in the hopes of divining its true nature — especially whether it’s displaying any cometary activity.

…According to Gray, Comet PanSTARRS appears to have entered the solar system from the direction of the constellation Lyra, within a couple of degrees of right ascension 18h 50m, declination +35° 13′. That’s tantalizingly close to Vega — and eerily reminiscent of the plot of the movie Contact — but its exact path doesn’t (yet) appear to link any particular star.

This object entered the solar system moving at 26 km (16 miles) per second. At that speed, in 10 million years it would traverse 8,200,000,000,000,000 km — more than 850 light-years.

Reminds me of a really good science fiction novel I read recently. They should keep an eye on it for as long as they can, just in case it suddenly changes course and settles into a more circular orbit around the Sun. In the unlikely case it does that, it might just be the biggest discovery in history.

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NASA instrument for European space telescope flawed and must be rebuilt

The NASA instrument for Europe’s Euclid optical/near-infrared space telescope has been found defective and must be rebuilt, thus delaying the launch of the telescope by at least one year.

What interested me about this telescope is its goals and specifications:

Euclid is a two-ton space telescope selected by ESA in 2011 as a medium-class mission in its Cosmic Vision program of space science missions. The spacecraft features a 1.2-meter telescope with visible and near-infrared instruments to study dark energy and dark matter, which combined account for about 95 percent of the universe. Euclid will operate at the Earth-sun L-2 Lagrange point, 1.5 million kilometers from Earth, that is used by other infrared astronomy missions.

With a mirror about half the size of Hubble’s, this telescope will act as a partial replacement and back up for it. In fact, it will likely make numerous ground-breaking discoveries, as every optical telescope placed above the atmosphere has so far done.

Meanwhile, the article provided no information on the flaws, who built the flawed instrument, and who will pay for the delays its failure will cause.

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Astronomers reduce estimate of still undiscovered dangerous asteroids

Astronomers have now reduced [pdf] their estimate of the number of still undiscovered dangerous Near Earth Asteroids (NEAs) that could impact the Earth from 100 to less than 40.

Observers have been cataloging potentially hazardous asteroids for decades. Based on the number of finds, the area of sky explored, and the limiting brightness our telescopes and cameras can reach, researchers can estimate what fraction of the NEA population has been detected so far and how many more objects lurk undiscovered. Harris has published numerous such estimates over the years. Recently he realized that his estimates have been plagued by a seemingly innocuous but nonetheless consequential round-off error. Once corrected, the estimated number of large (diameter > 1 kilometer) NEAs remaining to be discovered decreases from more than 100 to less than 40.

To put it mildly, there is a lot of uncertainty here. This also reminds me of the cavers’ joke question: “How many miles of unexplored passages does this cave have?”

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