Herschel Sees Budding Stars and a Giant, Strange Ring: Great Image of NGC 7538

The Herschel Space Observatory has uncovered a weird ring of dusty material while obtaining one of the sharpest scans to date of a huge cloud of gas and dust, called NGC 7538. Image credit: ESA/NASA/JPL-Caltech/Whitman College

The Herschel Space Observatory has uncovered a weird ring of dusty material while obtaining one of the sharpest scans to date of a huge cloud of gas and dust, called NGC 7538. The observations have revealed numerous clumps of material, a baker's dozen of which may evolve into the most powerful kinds of stars in the universe. Herschel is a European Space Agency mission with important NASA contributions.

"We have looked at NGC 7538 with Herschel and identified 13 massive, dense clumps where colossal stars could form in the future," said paper lead author Cassandra Fallscheer, a visiting assistant professor of astronomy at Whitman College in Walla Walla, Washington, and lead author of the paper published in The Astrophysical Journal. "In addition, we have found a gigantic ring structure and the weird thing is, we're not at all sure what created it."

NGC 7538 is relatively nearby, at a distance of about 8,800 light-years and located in the constellation Cepheus. The cloud, which has a mass on the order of 400,000 suns, is undergoing an intense bout of star formation. Astronomers study stellar nurseries such as NGC 7538 to better learn how stars come into being. Finding the mysterious ring, in this case, came as an unexpected bonus.

The cool, dusty ring has an oval shape, with its long axis spanning about 35 light-years and its short axis about 25 light-years. Fallscheer and her colleagues estimate that the ring possesses the mass of 500 suns. Additional data from the James Clerk Maxwell Telescope, located at the Mauna Kea Observatory in Hawaii, further helped characterize the odd ovoid. Astronomers often see ring and bubble-like structures in cosmic dust clouds. The strong winds cast out by the most massive stars, called O-type stars, can generate these expanding puffs, as can their explosive deaths as supernovas. But no energetic source or remnant of a deceased O-type star, such as a neutron star, is apparent within the center of this ring. It is possible that a big star blew the bubble and, because stars are all in motion, subsequently left the scene, escaping detection.

The observations were taken as part of the Herschel OB Young Stellar objects (HOBYS) Key Programme. The "OB" refers to the two most massive kinds of stars, O-type and B-type. These bright blue, superhot, short-lived stars end up exploding as supernovas, leaving behind either incredibly dense neutron stars or even denser black holes.

Stars of this caliber form from gassy, dusty clumps with initial masses dozens of times greater than the sun's; the 13 clumps spotted in NGC 7358, some of which lie along the edge of the mystery ring, all are more than 40 times more massive than the sun. The clumps gravitationally collapse in on themselves, growing denser and hotter in their cores until nuclear fusion ignites and a star is born. For now, early in the star-formation process, the clumps remain quite cold, just a few tens of degrees above absolute zero. At these temperatures, the clumps emit the bulk of their radiation in the low-energy, submillimeter and infrared light that Herschel was specifically designed to detect.

As astronomers continue probing these budding O-type giants in NGC 7358, the follow-up observations with other telescopes should also help in solving the puzzle of the humongous, dusty ring. "Further research to determine the mechanism responsible for creating the ring structure is necessary," said Fallscheer.

Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. While the observatory stopped making science observations in April 2013, after running out of liquid coolant as expected, scientists continue to analyze its data. NASA's Herschel Project Office is based at the Jet Propulsion Laboratory in Pasadena, California. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the U.S. astronomical community.

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More information is online at:

http://www.herschel.caltech.edu

http://www.nasa.gov/herschel

http://www.esa.int/SPECIALS/Herschel

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov 

Milky Way may bear 100 million life-giving planets, a whole lot of aliens?

This blog has speculated several times (e.g. here) about the probability of life elsewhere in the universe. A new study from Cornell University puts the number of possible life-supporting planets (in our own Milky Way galaxy alone) at about 100 million. On the face of it less than my own 'gestimate' but still pointing to a whole lot of aliens!

Planetary Habitability Laboratory, University of Puerto Rico at Arecibo

Here is their news report:

There are some 100 million other places in the Milky Way galaxy that could support complex life, report a group of university astronomers in the journal Challenges. They have developed a new computation method to examine data from planets orbiting other stars in the universe.

Their study provides the first quantitative estimate of the number of worlds in our galaxy that could harbor life above the microbial level.

“This study does not indicate that complex life exists on that many planets. We’re saying that there are planetary conditions that could support it. Origin of life questions are not addressed – only the conditions to support life,” according to the paper’s authors Alberto Fairén, Cornell research associate; Louis Irwin, University of Texas at El Paso (lead author); Abel Méndez, University of Puerto Rico at Arecibo; and Dirk Schulze-Makuch, Washington State University.

Fairen

“Complex life doesn’t mean intelligent life – though it doesn’t rule it out or even animal life – but simply that organisms larger and more complex than microbes could exist in a number of different forms. For example, organisms that form stable food webs like those found in ecosystems on Earth,” the researchers explain in an auxiliary statement.

The scientists surveyed more than 1,000 planets and used a formula that considers planet density, temperature, substrate (liquid, solid or gas), chemistry, distance from its central star and age. From this information, they developed and computed the Biological Complexity Index (BCI).

The BCI calculation revealed that 1 to 2 percent of the planets showed a BCI rating higher than Europa, a moon of Jupiter thought to have a subsurface global ocean that may harbor forms of life. With about 10 billion stars in the Milky Way galaxy, the BCI yields 100 million plausible planets.

Despite the large number of planets that could harbor complex life, the Milky Way is so vast that planets with high BCI values are very far apart, according to the scientists. One of the closest and most promising extrasolar systems, called Gliese 581, has two planets with the apparent, possible capacity to host complex biospheres. The distance from Earth to Gliese 581 is about 20 light years.

“It seems highly unlikely that we are alone,” say the researchers. “We are likely so far away from life at our level of complexity that a meeting with such alien forms might be improbable for the foreseeable future.”

The research, “Assessing the Possibility of Biological Complexity on Other Worlds, With an Estimate of the Occurrence of Complex Life in the Milky Way Galaxy,” in Challenges, received no external funding.

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Astronomers Confounded By Massive Rocky World, Kepler-10c

Kepler-10 System

An artist's conception shows the Kepler-10 system, home to two rocky planets. In the foreground is Kepler-10c, a planet that weighs 17 times as much as Earth and is more than twice as large in size. Planet formation theorists are challenged to explain how such a massive world could have formed.

Astronomers have discovered a rocky planet that weighs 17 times as much as Earth and is more than twice as large in size. This discovery has planet formation theorists challenged to explain how such a world could have formed.

"We were very surprised when we realized what we had found," said astronomer Xavier Dumusque of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, who led the analysis using data originally collected by NASA's Kepler space telescope.

Kepler-10c, as the planet had been named, had a previously measured size of 2.3 times larger than Earth, but its mass was not known until now. The team used the HARPS-North instrument on the Telescopio Nazionale Galileo in the Canary Islands to conduct follow-up observations to obtain a mass measurement of the rocky behemoth.

It was thought worlds such as this could not possibly exist. The enormous gravitational force of such a massive body would accrete a gas envelope during formation, ballooning the planet to a gas giant the size of Neptune or even Jupiter. However, this planet is thought to be solid, composed primarily of rock.

"Just when you think you've got it all figured out, nature gives you a huge surprise -- in this case, literally," said Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center in Moffett Field, California. "Isn't science marvelous?"

Kepler-10c orbits a sun-like star every 45 days, making it too hot to sustain life as we know it. It is located about 560 light-years from Earth in the constellation Draco. The system also hosts Kepler-10b, the first rocky planet discovered in the Kepler data.

The finding was presented at a meeting of the American Astronomical Society in Boston. Read more about the discovery in the Harvard-Smithsonian Center for Astrophysics news release.

NASA's Ames Research Center manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory, Pasadena, California, managed the Kepler mission's development.

Ball Aerospace and Technologies Corp. in Boulder, Colorado, developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

Credit NASA/JPL

For more information about the Kepler mission, visit:

http://www.nasa.gov/kepler

For more information about exoplanets and NASA's planet-finding program, visit:

http://planetquest.jpl.nasa.gov