A team led by Lucas Cieza (Universidad Diego Portales, Santiago, Chile) has produced the first image directly showing the water snowline in a protoplanetary disk, using the Atacama Large Millimeter/submillimeter Array (ALMA). It's fascinating to actually see a mechanism we've long discussed in these pages when analyzing exoplanetary systems (or for that matter, our own). We have a young star called V883 Orionis to thank for the possibility. It's an FU Orionis star of the kind we recently looked at in FU Orionis: Implications of Sudden Brightening for Planet Formation. And here, too, the implications are rich. FU Orionis stars are young, pre-main sequence objects that can produce extreme changes in magnitude and spectral type. The eponymous FU Orionis itself, 1500 light years away in the constellation Orion, underwent an event in 1936 that took it from a visual magnitude of 16.5 to 9.6. In the case of V883 Orionis, a similar outburst in temperature and luminosity has heated the...

A brown dwarf as a 'quieter' version of Jupiter? That's more or less the picture offered in a new paper on WISE 0855 from Andrew Skemer (UC-Santa Cruz) and colleagues. Here we're working in the Solar System's close neighborhood -- WISE 0855 is a scant 7.2 light years from Earth -- and we're observing an object that is the coldest known outside of the Solar System. That makes the observational task difficult, but it has yielded rich results in the discovery of clouds of water or water ice. We learn that WISE 0855 is about five times the mass of Jupiter, with a temperature in the range of 250 K (-23 Celsius). This is the nearest known object of planetary mass, but it is too faint to characterize with conventional spectroscopy -- separating light into its component wavelengths -- in the optical or near infrared. But it turns out the object can be studied through thermal emissions from deep in its atmosphere in the range of 5 µm (a range frequently used to study Jupiter's own deep...

Into the annals of oddball orbits now comes HD 131399Ab, a planet whose wide orbit inside a triple-star system is unlike anything we've yet seen. 320 light years from Earth in the constellation Centaurus, this is a gas giant of about four Jupiter masses that was discovered through direct imaging. The discovery was made with the European Southern Observatory's Very Large Telescope in Chile using the SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch) instrument, which exploits differential imaging to screen stellar light from planetary signatures. HD 131399Ab is the first exoplanet discovered by SPHERE, which incorporates adaptive optics, a coronagraph and, with its differential imaging features, distinguishes a planet by the polarization of reflected light. Stars emit unpolarized light -- here the electromagnetic waves oscillate randomly, and in different directions, as explained in this ESO news release. But light reflected from a planetary surface is partially polarized,...

If our Solar System had a ‘hot Jupiter’ that migrated inward after Mars, Earth and Venus had formed, would any of the terrestrial planets have survived? It’s a question worth pondering given how many hot Jupiters we’ve turned up, raising the question of how these planets form in the first place. One possibility is formation in situ, close to the parent star. But there is also an argument for migration, with planets forming in cooler regions further out in the system and migrating inward as a result of interactions with the protoplanetary disk or other planets. Perhaps the planet known as K2-33b can help us with some of this. It is no more than 11 million years old, in an orbit that creates a transit every 5.4 days. With follow-up observations by the MEarth arrays on Mount Hopkins (AZ) and at the Cerro Tololo Inter-American Observatory in Chile, researchers led by Andrew Mann (University of Texas at Austin) have been able to determine that K2-33b is a Neptune-class world some five...

I would like to thank the many Centauri Dreams readers who contributed to the successful Kickstarter campaign to fund a year's worth of study of KIC 8462852. As I write, there is less than an hour to go, but we have already gone well over the needed $100,000 mark. Congratulations to Tabitha Boyajian, and thanks for all the work she and her colleagues have put into this effort. Now we have a year of observations ahead using the Las Cumbres Observatory Global Telescope Network. The long-term observations will be crucial because we don't know what to expect in terms of sudden dimming in this star's light curve. What a pleasure it is to write for this audience. Readers here have played a large role in pushing this project over the top, and we'll follow the work on KIC 8462852 closely in coming days. Meanwhile, have a look at Penn State's Jason Wright discussing 'Tabby's Star.' [youtube jjh0oK7ZyfM 500 416] Speaking of Unusual Stars… If KIC 8462852 is a star that some believe is...

Given everything we're learning about planets around other suns, it's frustrating that we have so little information about the chemical composition of the rocky planets we've found thus far. Now we have a new study, announced at the San Diego meeting of the American Astronomical Society, that offers data on a 'planet-like body' whose surface layers are being consumed by the white dwarf SDSSJ1043+0855. Although it's been known for some time that the star has been devouring rocky material orbiting around it, the new work offers a striking view of the accretion process and the composition of what was once a differentiated body. At least, that's the best interpretation of the data taken from the Keck Observatory's HIRES spectrometer (installed on the 10-meter Keck I instrument) and the Hubble Space Telescope. White dwarf stars are the remains of stars like the Sun -- this one was once a few times the Sun's mass -- that have gone through their red giant phase and expelled all their outer...

Before getting into today's subject, the discovery of an interesting long-period circumbinary planet, I want to make another pitch for Centauri Dreams readers to support the Kickstarter campaign for Tabby's Star. I've written often about this mysterious star whose light curves are anomalous and demand further study. Trying to find out what's happening around KIC 8462852 means acquiring more data, and the Kickstarter campaign would provide an entire year of observations using the Las Cumbres Observatory Global Telescope Network. We're now down to 48 hours and of the $100,000 needed, about three-fourths has been raised. Coming down the homestretch, the remaining $24,000 should be achievable, but it looks to be a dramatic finish. If you haven't been following the KIC 8462852 story, you can check the archives here, or for a quick overview, see my article A Kickstarter Campaign for KIC 8462852. Whatever you can do to help would be hugely appreciated as we try to learn as much as possible...