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  • richardmitnick 4:07 pm on November 2, 2017 Permalink | Reply
    Tags: , , , Centauri Dreams, Cold Trap in a Hot Jupiter’s Atmosphere, , Kepler-13Ab, Transit spectroscopy   

    From Centauri Dreams: “Cold Trap in a Hot Jupiter’s Atmosphere” 

    Centauri Dreams

    November 2, 2017
    Paul Gilster

    The other day I looked at how we can use transit spectroscopy to study the atmospheres of exoplanets. Consider this a matter of eclipses, the first occurring when the planet moves in front of its star as seen from Earth.

    Planet transit. NASA/Ames

    We can measure the size of the planet and also see light from the star as it moves through the planetary atmosphere, giving us information about its composition. The secondary eclipse, when the planet disappears behind the star, is also quite useful. Here, we can study the atmosphere in terms of its thermal variations.

    In my recent post, I used a diagram from Sara Seager to show primary and secondary eclipse in relation to a host star. The image below, by Josh Winn, is useful because it drills down into the specifics.

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    Image: A comparison between transits and secondary eclipses (also sometimes called occultations). In a planetary transit, the planet crosses in front of the star (see lower dip) blocking a fraction of the star’s brightness. In a secondary eclipse, the planet crosses behind the star, blocking the planet’s brightness (see dip in the middle). The latter dip in brightness is fainter due to the faintness of the planet. Credit: Josh Winn. See A New Discovery of a Secondary Eclipse for more background as it applies to the HAT-P-11 system.

    Secondary eclipses have been significant in the study of Kepler-13Ab, a world where conditions could not be more different on the planet’s nightside vs. its dayside. A ‘hot Jupiter’ some 1730 light years from Earth, this is a world close enough to its parent star that it is tidally locked. Researchers led by Thomas Beatty (Pennsylvania State) have used the Hubble Space Telescope to determine that that the dayside here can surpass a blistering 3000 Kelvin.

    By contrast, the nightside of Kepler-13Ab, turned forever away from the star, is a place where titanium oxide snow can fall. The process is intriguing: Any titanium oxide gas on the star-facing side is carried by strong winds around to the nightside, where the gas condenses into clouds and eventually falls as snow. A gravitational tug six times greater than Jupiter’s pulls the titanium oxide into the lower atmosphere, forming a ‘cold trap’ — an atmospheric layer that is colder than the layers both below and above it. Ascending gases drop back into the trap.

    Science paper:
    Evidence for Atmospheric Cold-trap Processes in the Noninverted Emission Spectrum of Kepler-13Ab Using HST/WFC3

    Centauri Dreams

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

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  • richardmitnick 1:28 pm on September 29, 2017 Permalink | Reply
    Tags: , , , Centauri Dreams, ,   

    From Centauri Dreams: “Project Blue: Looking for Terrestrial Worlds at Alpha Centauri” 

    Centauri Dreams

    September 29, 2017
    Paul Gilster

    Eduardo Bendek’s ACEsat, conceived at NASA Ames by Bendek and Ruslan Belikov, seemed to change the paradigm for planet discovery around the nearest stellar system. The beauty of Alpha Centauri is that the two primary stars present large habitable zones as seen from Earth, simply because the system is so close to us.

    ESO Red Dots Campaign

    The downside, in terms of G-class Centauri A and K-class Centauri B, is that their binary nature makes filtering out starlight a major challenge.

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    Image: The Alpha Centauri system. The combined light of Centauri A (G-class) and Centauri B (K-class) appears here as a single overwhelmingly bright ‘star.’ Proxima Centauri can be seen circled at bottom right. Credit: European Southern Observatory.

    If we attack the problem from the ground, ever bigger instruments seem called for, like the European Southern Observatory’s Very Large Telescope…

    ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    …in conjunction with the VISIR instrument (VLT Imager and Spectrometer for mid-Infrared) that Breakthrough Initiatives is now working with the ESO to enhance.

    Breakthrough Listen Project

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    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA



    GBO radio telescope, Green Bank, West Virginia, USA


    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

    Or perhaps one of the extremely large telescopes now in the works, like the Thirty Meter Telescope in Hawaii, or the Giant Magellan Telescope in Chile.

    TMT-Thirty Meter Telescope, proposed and now approved for Mauna Kea, Hawaii, USA4,207 m (13,802 ft) above sea level

    Giant Magellan Telescope, to be at Las Campanas Observatory, to be built some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high

    And if we did this from space, surely it would be an expensive platform. Except that ACEsat wasn’t expensive, nor was it large. It was designed to do just one thing and do it well.

    While NASA turned down Bendek and Belikov’s idea for Small Explorer funding, the striking thing is that it would have fit that category’s definition. ACEsat was designed as a 30 to 45 cm space telescope (you can see a Belikov presentation on the instrument here, or for that matter, read Ashley Baldwin’s ACEsat: Alpha Centauri and Direct Imaging). The small instrument now being proposed by an initiative called Project Blue builds on many of the ACEsat concepts.

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    Project Blue. Many Partners. the BoldlyGo Institute and its Project Blue partners – including the SETI Institute, the University of Massachusetts at Lowell, and Mission Centaur.

    It would run perhaps $50 million even though the original ACEsat was a $175 million design.

    In other words, compared to the $8 billion James Webb Space Telescope, Project Blue’s instrument is almost inexpensive enough to be a rounding error. A privately funded initiative out of the Boldly Go Institute, in partnership with the SETI Institute, Mission Centaur, and UMass Lowell, the telescope shows its pedigree both in its low cost and big scientific return. It seems the ACEsat concept is just too good to go away.

    So now we have Project Blue, which is all about seeing the blue of an Earth-like world around one or even both of the Sun-like stars of the Alpha Centauri system. No one discounts the value of the planet already discovered around Proxima Centauri, but the project hopes to find an Earth 2.0, a rocky planet in a habitable zone orbit around a star like our own. That would mean no tidal locking, no small red dwarf primary, and a year measured in months rather than days.

    4
    Image: An Earth-like planet around one of the primary Alpha Centauri stars, as simulated by Project Blue.

    The project’s new Indiegogo campaign has been set up to raise $175,000 to help establish mission requirements, including the design of an initial system architecture to which computer simulations can be applied by way of testing ideas and simulating outcomes. The launch goal of 2021 is ambitious indeed, as is the low $50 million budget profile, but the project’s backers believe their work can leverage advances in the small satellite industry and imaging systems to pull it off. An explicit goal is to engage the public while tapping the original NASA work.

    The project’s connection to NASA is in the form of a cooperative agreement explained on the Indiegogo site:

    “The BoldlyGo Institute and NASA have signed a Space Act Agreement to cooperate on Project Blue, a mission to search for potentially habitable Earth-size planets in the Alpha Centauri system using a specially designed space telescope. The agreement allows NASA employees – scientists and engineers – to interact with the Project Blue team through its mission development phases to help review mission design plans and to share scientific results on Alpha Centauri and exoplanets along with the latest technology tests being undertaken at NASA facilities. The agreement also calls for the raw and processed data from Project Blue to be made available to NASA within one year of its acquisition on orbit via a publicly accessible online data archive. The Project Blue team has been planning such an archive for broadly sharing the data with the global astronomical community and for enabling citizen scientist participation.”

    And I notice that Eduardo Bendek is among the ranks of an advisory committee (available here) that includes the likes of exoplanet hunters Olivier Guyon, Debra Fischer, Jim Kasting and Maggie Turnbull. But have a look at the advisor page; every one of these scientists is playing a significant role in our discovery and evaluation of new exoplanetary systems.

    Thus we can say that ACEsat lives on in this new incarnation that will benefit from the input of its original designers. The spacecraft would spend two years in low Earth orbit accumulating thousands of images with the help of an onboard coronagraph to remove light from the twin stars, along with a deformable mirror, low-order wavefront sensors, and control algorithms to manage incoming light, enhancing image contrast with software processing methods.

    Unlike the major observatories we’re soon to be launching — not just the James Webb Space Telescope but the Transiting Exoplanet Survey Satellite (TESS) — the Project Blue observatory will be dedicated to a single target, with no other observational duties.

    NASA/ESA/CSA Webb Telescope annotated

    NASA/TESS

    A photograph of an Earth-like planet 40 trillion kilometers away gives us a sense of the changes in scale that have occurred since Voyager 1’s ‘pale blue dot’ photograph. But we already knew that Earth was inhabited. Now, gaining spectral information about a blue and green world around a nearby star would allow us to determine whether biosignature gases could be found in its atmosphere, potential signs of life that would mark a breakthrough in our science. The degree of public involvement assumed in the project makes the quest all the more tantalizing.

    Centauri Dreams

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 1:47 pm on September 19, 2017 Permalink | Reply
    Tags: , , , Centauri Dreams, , Red Edge’ Biomarkers on M-dwarf Planets   

    From Centauri Dreams: “‘Red Edge’ Biomarkers on M-dwarf Planets” 

    Centauri Dreams

    September 19, 2017
    Paul Gilster

    When we think about the markers of possible life on other worlds, vegetation comes to mind in an interesting way. We’d like to use transit spectroscopy to see biosignatures, gases that have built up in the atmosphere because of ongoing biological activity. But plants using photosynthesis offer us an additional option. They absorb sunlight from the visible part of the spectrum, but not longer-wavelength infrared light. The latter they simply reflect.

    What we wind up with is a possible observable for a directly imaged planet, for if you plot the intensity of light against wavelength, you will find a marked drop known as the ‘red edge.’ It shows up when going from longer infrared wavelengths into the visible light region. The red-edge position for Earth’s vegetation is fixed at around 700–760 nm. What we’d like to do is find a way to turn this knowledge into a practical result while looking at exoplanets. Where would we find the red edge on planets circling stars of a different class than our own?

    Led by Kenji Takizawa, researchers at the Astrobiology Center (ABC) of National Institutes of Natural Science (NINS) in Japan have taken up the question with regard to M-dwarfs. These stars have lower surface temperatures than the Sun and emit more strongly at near-infrared wavelengths than at visible wavelengths. Assuming vegetation in such an environment evolves to use the most abundant photons for photosynthesis, shouldn’t we expect the red edge to shift accordingly? Perhaps not, argue the authors, as only blue-green light penetrates beyond a few meters of water. Visible light, in other words, may play a larger role than we imagine.

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    Image: Artist’s impressions of a habitable planet around M-dwarfs (left) and primordial Earth (right). Credit: ABC/NINS.

    Centauri Dreams


    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 3:59 pm on August 15, 2017 Permalink | Reply
    Tags: , , , Centauri Dreams, ,   

    From Centauri Dreams: “TRAPPIST-1: The Importance of Age” 

    Centauri Dreams

    If life can arise around red dwarf stars, you would think TRAPPIST-1 would be the place to look. Home to seven planets, this ultracool M8V dwarf star about 40 light years away in Aquarius has been around for a long time. The age range in a new study on the matter goes from 5.4 billion years up to almost ten billion years. And we have more than one habitable zone planet to look at.

    Adam Burgasser (UC-San Diego) and Eric Mamajek (JPL) are behind the age calculations, which appear in a paper that has been accepted at The Astrophysical Journal. We have no idea how long it takes life to emerge, having only one example to work with, but it’s encouraging that we find evidence for it very early in Earth’s history, dating back some 3.8 billion years. But we also have much to learn about habitability around red dwarfs in general.

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile interior

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile

    The good thing about being a somewhat older red dwarf is that flare activity should have slowed over time, a fact that the authors confirm. This doesn’t make it necessarily benign. In fact, as the paper points out, “…despite TRAPPIST-1’s modest emission as compared to other late-M dwarfs, the radiation and particle environment is still extreme as compared to the Earth.”

    Centauri Dreams


    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 7:58 am on July 20, 2017 Permalink | Reply
    Tags: , , , Centauri Dreams, , Nickel 1-meter telescope at Lick Observatory, NIROSETI-Near-Infrared Optical SETI instrument, Optical SETI, Radio SETI, , Shelley Wright,   

    From Centauri Dreams: “Making Optical SETI Happen” 

    Centauri Dreams

    July 18, 2017
    Paul Gilster

    Yesterday I made mention of the Schwartz and Townes paper “Interstellar and Interplanetary Communication by Optical Masers,” which ran in Nature in 1961 (Vol. 190, Issue 4772, pp. 205-208). Whereas the famous Cocconi and Morrison paper that kicked off radio SETI quickly spawned an active search in the form of Project Ozma, optical SETI was much slower to develop. The first search I can find is a Russian project called MANIA, in the hands of V. F. Shvartsman and G. M. Beskin, who searched about 100 objects in the early 1970s, finding no significant brightness variations within the parameters of their search.

    If you want to track this one down, you’ll need a good academic library, as it appears in the conference proceedings for the Third Decennial US-USSR Conference on SETI, published in 1993. Another Shvartsman investigation under the MANIA rubric occurred in 1978. Optical SETI did not seem to seize the public’s imagination, perhaps partially because of the novelty of communications through the recently discovered laser. We do see several optical SETI studies at UC-Berkeley’s Leuschner Observatory and Kitt Peak from 1979 to 1981, the work of Francisco Valdes and Robert Freitas, though these were searches for Bracewell probes within the Solar System rather than attempts to pick up laser transmissions from other star systems.

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    Harvard’s Paul Horowitz, a key player in the development of optical SETI. Credit: Harvard University.

    This was an era when radio searches for extraterrestrial technology had begun to proliferate, but despite the advocacy of Townes and others (and three conferences Townes helped create), it wasn’t until the 1990s that optical SETI began to come into its own. Charles Townes himself was involved in a search for laser signals from about 300 nearby stars in the ‘90s, using the 1.7-meter telescope on Mt. Wilson and reported on at the 1993 conference. Stuart Kingsley began an optical SETI search using the 25-centimeter telescope at the Columbus Optical SETI Observatory (COSETI) in 1990, while Gregory Beskin searched for optical signals at the Special Astrophysical Observatory run by the Russian Academy of Sciences in the Caucasus in 1995.

    Optical SETI’s advantages were beginning to be realized, as Andrew Howard (Caltech) commented in a 2004 paper:

    “The rapid development of laser technology since that time—a Moore’s law doubling of capability roughly every year—along with the discovery of many microwave lines of astronomical interest, have lessened somewhat the allure of hydrogen-line SETI. Indeed, on Earth the exploitation of photonics has revolutionized communications technology, with high-capacity fibers replacing both the historical copper cables and the long-haul microwave repeater chains. In addition, the elucidation (Cordes & Lazio 1991) of the consequences to SETI of interstellar dispersion (first seen in pulsar observations) has broadened thinking about optimum wavelengths. Even operating under the prevailing criterion of minimum energy per bit transmitted, one is driven upward to millimetric wavelengths.”

    In the late 90’s, the SETI Institute, as part of a reevaluation of SETI methods, recommended and then co-funded several optical searches including one by Dan Werthimer and colleagues at UC Berkeley and another by a Harvard-Smithsonian team including Paul Horowitz and Andrew Howard. The Harvard-Smithsonian group also worked in conjunction with Princeton University on a detector system similar to the one mounted on Harvard’s 155-centimeter optical telescope. A newer All-Sky Optical SETI (OSETI) telescope, set up at the Oak Ridge Observatory at Harvard and funded by The Planetary Society, dates from 2006.

    4
    http://seti.harvard.edu/oseti/allsky/allsky.htm

    5
    http://www.setileague.org/photos/oseti3.htm

    6
    http://seti.harvard.edu/oseti/

    At Berkeley, the optical SETI effort is led by Werthimer, who had built the laser detector for the Harvard-Smithsonian team. Optical SETI efforts from Leuschner Observatory and Lick Observatory were underway by 1999. Collaborating with Shelley Wright (UC Santa Cruz), Remington Stone (UC Santa Cruz/Lick Observatory), and Frank Drake (SETI Institute), the Berkeley group has gone on to develop new detector systems to improve sensitivity. As I mentioned yesterday, UC-Berkeley’s Nate Tellis, working with Geoff Marcy, has analyzed Keck archival data for 5,600 stars between 2004 and 2016 in search of optical signals.

    Working in the infrared, the Near-Infrared Optical SETI instrument (NIROSETI) is designed to conduct searches at infrared wavelengths. Shelley Wright is the principal investigator for NIROSETI, which is mounted on the Nickel 1-meter telescope at Lick Observatory, seeing first light in March of 2015. The project is designed to search for nanosecond pulses in the near-infrared, with a goal “to search not only for transient phenomena from technological activity, but also from natural objects that might produce very short time scale pulses from transient sources.” The advantage of near-infrared is the decrease in interstellar extinction, the absorption by dust and gas that can sharply impact the strength of a signal.

    7
    Shelley Wright, then a student at UC-Santa Cruz, helped build a detector that divides the light beam from a telescope into three parts, rather than just two, and sends it to three photomultiplier tubes. This arrangement greatly reduces the number of false alarms; very rarely will instrumental noise trigger all three detectors at once. The three-tube detector is in the white box attached here to the back of the 1-meter Nickel Telescope at Lick Observatory. Credit: Seth Shostak.

    8
    UCSC Lick Observatory Nickel Telescope

    I might also mention METI International’s Optical SETI Observatory at Boquete, Panama. The idea is to put the optical SETI effort in context. With the SETI Institute now raising money for its Laser SETI initiative — all-sky all-the-time — the role of private funding in making optical SETI happen is abundantly clear. And now, of course, we also have Breakthrough Listen, which in addition to listening at radio wavelengths at the Parkes instrument in Australia and the Green Bank radio telescope in West Virginia, is using the Automated Planet Finder at Lick Observatory to search for optical laser transmissions.

    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia



    GBO radio telescope, Green Bank, West Virginia, USA

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    Funded by the Breakthrough Prize Foundation, the project continues the tradition of private funding from individuals, institutions (the SETI Institute) and organizations like The Planetary Society to get optical SETI done.

    Centauri Dreams


    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 3:46 pm on July 19, 2017 Permalink | Reply
    Tags: , Centauri Dreams, , , , , Seth Shostak SETI Institute Astronomer, SETI Allen Telescope Array, U Chicago Yerkes Observatory   

    From Centauri Dreams: “Keeping an Eye on Ross 128” 

    Centauri Dreams

    July 19, 2017
    Paul Gilster

    1
    A screen shot from Abel Méndez’s lab note titled “Strange Signals from the Nearby Red Dwarf Star Ross 128.” Credit: Planetary Habitability Laboratory/University of Puerto Rico, Arecibo/Aladin Sky Atlas.

    Frank Elmore Ross (1874-1960), an American astronomer and physicist, became the successor to E. E. Barnard at Yerkes Observatory.

    1
    U Chicago Yerkes Observatory

    2
    U Chicago Yerkes Observatory interior

    Barnard, of course, is the discoverer of the high proper motion of the star named after him, alerting us to its proximity.

    3
    http://www.daviddarling.info/encyclopedia/B/BarnardsStar.html

    And as his successor, Ross would go on to catalog over 1000 stars with high proper motion, many of them nearby. Ross 128, now making news for what observers at the Arecibo Observatory are calling “broadband quasi-periodic non-polarized pulses with very strong dispersion-like features,” is one of these, about 11 light years out in the direction of Virgo.

    NAIC/Arecibo Observatory, Puerto Rico, USA

    Any nearby stars are of interest from the standpoint of exoplanet investigations, though thus far we’ve yet to discover any companions around Ross 128. An M4V dwarf, Ross 128 has about 15 percent of the Sun’s mass. More significantly, it is an active flare star, capable of unpredictable changes in luminosity over short periods. Which leads me back to that unusual reception. The SETI Institute’s Seth Shostak described it this way in a post:

    “What the Puerto Rican astronomers found when the data were analyzed was a wide-band radio signal. This signal not only repeated with time, but also slid down the radio dial, somewhat like a trombone going from a higher note to a lower one.”

    And as Shostak goes on to say, “That was odd, indeed.”

    It’s this star’s flare activity that stands out for me as I look over the online announcement of its unusual emissions, which were noted during a ten-minute spectral observation at Arecibo on May 12. Indeed, Abel Mendez, director of the Planetary Habitability Laboratory at Arecibo, cited Type II solar flares first in a list of possible explanations, though his post goes on to note that such flares tend to occur at lower frequencies. An additional novelty is that the dispersion of the signal points to a more distant source, or perhaps to unusual features in the star’s atmosphere. All of this leaves a lot of room for investigation.

    We also have to add possible radio frequency interference (RFI) into the mix, something the scientists at Arecibo are examining as observations continue. The possibility that we are dealing with a new category of M-dwarf flare is intriguing and would have obvious ramifications given the high astrobiological interest now being shown in these dim red stars.

    All of this needs to be weighed as we leave the SETI implications open. The Arecibo post notes that signals from another civilization are “at the bottom of many other better explanations,” as well they should be assuming those explanations pan out. But we should also keep our options open, which is why the news that the Breakthrough Listen initiative has now observed Ross 128 with the Green Bank radio telescope in West Virginia is encouraging.



    GBO radio telescope, Green Bank, West Virginia, USA

    No evidence of the emissions Arecibo detected has turned up in the Breakthrough Listen data. We’re waiting for follow-up observations from Arecibo, which re-examined the star on the 16th, and Mendez in an update noted that the SETI Institute’s Allen Telescope Array had also begun observations.

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA

    Seth Shostak tells us that the ATA has thus far collected more than 10 hours of data, observations which may help us determine whether the signal has indeed come from Ross 128 or has another source.

    “We need to get all the data from the other partner observatories to put all things together for a conclusion,” writes Mendez. “Probably by the end of this week.”
    [Shostak]

    Or perhaps not, given the difficulty of detecting the faint signal and the uncertainties involved in characterizing it. If you’re intrigued, an Arecibo survey asking for public reactions to the reception is now available.

    I also want to point out that Arecibo Observatory is working on a new campaign to observe stars like Ross 128, the idea being to characterize their magnetic environment and radiation. One possible outcome of work like that is to detect perturbations in their emissions that could point to planets — planetary magnetic fields could conceivably affect flare activity. That’s an intriguing way to look for exoplanets, and the list being observed includes Barnard’s Star, Gliese 436, Ross 128, Wolf 359, HD 95735, BD +202465, V* RY Sex, and K2-18.

    A final note: Arecibo is now working with the Red Dots campaign in coordination with other observatories to study Barnard’s Star, for which there is some evidence of a super-Earth mass planet. More on these observations can be found in this Arecibo news release.

    ESO Red Dots Campaign

    Centauri Dreams


    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 5:20 pm on July 18, 2017 Permalink | Reply
    Tags: Bernard's Star, Centauri Dreams, , , Paul Gilster   

    From Red Dots: “Dreaming Peter van de Kamp’s dream” 

    Red Dots

    7.18.17
    by Paul Gilster, writer and author of “Centauri Dreams”
    Edited by Zaira M. Berdiñas

    1

    The Red Dots campaign to study Proxima Centauri, Barnard’s Star and Ross 154 gives us a cannily chosen set of targets. All red dwarfs much smaller than the Sun, these stars offer us the opportunity of atmospheric analysis of any planets discovered there by future space-and ground-based instruments because all are close. At 4.2 light years, Proxima Centauri is nearest to the Sun, but Barnard’s Star is a scant 6 light years out, making it the closest known star other than the three Alpha Centauri stars. Ross 154 comes in at just under 10 light years, still very much in the local neighborhood in astronomical terms.

    2
    The proper motion of Barnard’s Star between the years 1991 and 2007, an indication of its proximity to our own Solar System. No image credit.

    But it is not just their proximity that makes these stars interesting. We’d like to know how stars like this age, considering that young M-dwarfs can show strong flare activity. All three of these stars do, with Proxima Centauri and Ross 154 being catalogued as UV Ceti stars; i.e., stars that produce major flares every few days. Barnard’s Star is of a variable category known as BY Draconis, stars that show starspots, variations in luminosity and other activity.

    So consider the spread here. Proxima Centauri is thought to be about 4.85 billion years old, while Barnard’s Star is perhaps twice that. Ross 154, however, shows a high rate of rotation — 3.5 ± 1.5 km/s — that indicates a younger star, perhaps one less than a billion years old. Thus we have three stars and possible planets at markedly different stages of development, giving us the ability to take a deeper look into flare activity on M-dwarfs as they age, and to assess flare effects on planetary habitability, assuming Barnard’s Star and Ross 154 do have planets. We’ll also be investigating the prospects for multiple planets around Proxima Centauri itself.

    Barnard’s Star has already produced its own share of notoriety. Working at the Sproul Observatory (Swarthmore College, Pennsylvania), astronomer Peter van de Kamp examined 2,413 photographic plates of the star taken between 1916 and 1962. The astronomer observed what he believed to be a telltale wobble in the motion of Barnard’s Star that fit the profile of a planet about 1.6 times Jupiter’s mass in an orbit at 4.4 AU [1]. He would later suggest the possibility of two gas giants here [2], and by 1973, Oliver Jensen (University of British Columbia) and Tadeusz Ulrych had upped the number to three [3].

    4
    Peter van de Kamp (right) and the the 61 cm Sproul refracting telescope (left) he used in his work on Barnard’s Star.

    If confirmed, these would have been the first planets ever detected outside our Solar System, but it was not to be. Follow-up studies by George Gatewood (University of Pittsburgh) and John Hershey (also at the Sproul Observatory) found systematic errors in van de Kamp’s work. The culprit: Lens adjustments to the Swarthmore instrument that were later confirmed by Hershey when he found an identical wobble in the M-dwarf Gliese 793 [4]. Subsequent work by Gatewood and, later, Jieun Choi (UC Berkeley) would be able to detect no planets [5],[6].

    5
    Figure from Gatewood & Eichhorn that shows the disagreement between their data (black dots) and the model fitted by Van de Kamp using the data from the Sproul Observatory (dashed line).

    Peter van de Kamp’s tool was astrometry, meaning he used precise measurements in the proper motion of the star to look for the presence of planets, finding minute variations on photographic plates that were consistent with the hypothesis. His observational skills and persistence were rightly praised, but errors in his instrument negated what would have been a major discovery.

    So what do we have today? We can rule out gas giants at Barnard’s Star thanks to continuing Doppler monitoring, but we can’t yet rule out small rocky planets of the kind we are now turning up around other M-dwarfs in data from the Kepler mission.

    NASA/Kepler Telescope

    Kepler has shown us that planets of a few times Earth-mass are not uncommon, while a 2013 study by Ravi Kopparapu (Pennsylvania State) found that about half of all M-dwarfs should have Earth-size planets in the habitable zone[7]. What might Red Dots uncover around this tantalizingly close star?

    It was Peter van de Kamp’s work that helped the energetic team of starship designers behind the British Interplanetary Society’s Project Daedalus choose Barnard’s Star as their destination. And physicist Robert Forward, no stranger to fiction, would use a planetary system around Barnard’s Star as the setting for his novel ​Rocheworld​ (1984). The system is reached by a lightsail beamed by a laser array, a concept not unfamiliar to today’s Breakthrough Starshot (read the article by Avi Loeb), which envisions sending small sails by laser to Proxima Centauri.

    How fitting, then, that Red Dots should home in on this interesting system, along with a return to Proxima Centauri and a deep exploration of Ross 154 as well. Red dwarf stars like these account for as much as 80 percent of the stars in our galaxy. The new campaign will let us see, in real time, no less, just how this inspiring search of nearby dwarfs proceeds.

    References:

    van de Kamp, P. “Astrometric study of Barnard’s star from plates taken with the 24-inch Sproul refractor”, Astronomical Journal, 68, 515, (1963).
    van de Kamp, P. “Alternate dynamical analysis of Barnard’s star”, Astronomical Journal, 74, 757, (1969).
    Jensen, O. G. & Ulrych, T. “An analysis of the perturbations on Barnard’s Star”, Astronomical Journal, 78, 1104, (1973).
    Hershey, J. L. “Astrometric analysis of the field of AC +65 6955 from plates taken with the Sproul 24-inch refractor”, Astronomical Journal, 78, 421, (1973).
    Gatewood, G. & Eichhorn, H. “An unsuccessful search for a planetary companion of Barnard’s star BD +4 3561”, Astronomical Journal, 78, 769, (1973).
    Choi, J. et al. “Precise Doppler Monitoring of Barnard’s Star”, Astrophysical Journal, 764, 131, (2013).
    Kopparapu, R. K. “A Revised Estimate of the Occurrence Rate of Terrestrial Planets in the Habitable Zones around Kepler M-dwarfs”, Astrophysical Journal, 767, L8, (2013).

    See the full article here .

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    Red dots is a project to attempt detection of the nearest terrestrial planets to the Sun. Terrestrial planets in temperate orbits around nearby red dwarf stars can be more easily detected using Doppler spectroscopy, hence the name of the project.

    ESO 3.6m telescope & HARPS at LaSilla, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO/HARPS at La Silla

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

     
  • richardmitnick 9:45 am on July 13, 2017 Permalink | Reply
    Tags: "Planetary mass binary", , , , , Centauri Dreams, , L7 dwarf 2MASS J11193254–1137466, TW Hydrae Association   

    From Centauri Dreams: “A Binary ‘Rogue’ Planet?” 

    Centauri Dreams

    July 12, 2017
    Paul Gilster

    “Planetary mass binary” is an unusual term, but one that seems to fit new observations of what was thought to be a brown dwarf or free-floating large Jupiter analog, and now turns out to be two objects, each of about 3.7 Jupiter masses. That puts them into planet-range when it comes to mass, as the International Astronomical Union normally considers objects below the minimum mass to fuse deuterium (13 Jupiter masses) to be planets. This is the lowest mass binary yet discovered.

    A team led by William Best (Institute for Astronomy, University of Hawaii) went to work on the L7 dwarf 2MASS J11193254–1137466 with the idea of determining what they assumed to be the single object’s mass and age. It was through observations with the Keck II telescope in Hawaii that they discovered the binary nature of their target.


    Keck Observatory, Mauna Kea, Hawaii, USA

    The separation between the two objects is about 3.9 AU, based upon the assumption that the binary is around 160 light years away, the distance of the grouping of stars called the TW Hydrae Association.

    Let’s pause on this for a moment. The TW Hydrae Association has come up in these pages in the past, as a so-called ‘moving group’ that contains stars that share a common origin, and thus are similar in age and travel through space together. Moving groups are obviously useful — if astronomers can determine that a star is in one, then its age and distance can be inferred from the other stars in the group. Best and colleagues determined from key factors like sky position, proper motion, and radial velocity that there was about an 80 percent chance that 2MASS J11193254–1137466AB is a member of the TW Hydrae Association.

    1
    Keck images of 2MASS J11193254–1137466 reveal that this object is actually a binary system. A similar image of another dwarf, WISEA J1147-2040, is shown at bottom left for contrast: this one does not show signs of being a binary at this resolution. Credit: Best et al. 2017.

    Determining a brown dwarf’s age is tricky business because these objects cool continuously as they age, which means that brown dwarfs of different masses and ages can wind up with the same luminosity. The authors point out that this mass-age-luminosity degeneracy makes it hard to figure out their characteristics without knowing at least two of the three parameters. Membership in a moving group like the TW Hydrae Association gives us an age of about 10 million years but also provides mass estimates from evolutionary models.

    And a binary system hits the jackpot, for now we can study the orbits of the two objects to work out model-independent masses, which is how Best drilled down to the 3.7 Jupiter mass result for each binary member here. The authors consider the binary a benchmark for tests of evolutionary and atmospheric models of young planets, and go on to speculate about its possible origins:

    “The isolation of 2MASS J1119−1137AB strongly suggests that it is a product of normal star formation processes, which therefore must be capable of making binaries with ≲ 5 MJup components. 2MASS J1119−1137AB could be a fragment of a higher-order system that was ejected via dynamical interactions (Reipurth & Mikkola 2015 ApJ), although the lack of any confirmed member of TWA within 10° (projected separation ≈ 5 pc) of 2MASS J1119−1137 makes this scenario unlikely. Formation of very low mass binaries in extended massive disks around Sun-like stars followed by ejection into the field has been proposed by, e.g., Stamatellos & Whitworth (2009), but disks of this type have not been observed.”

    2
    The positions of 2MASS J11193254–1137466A and B on a color-magnitude diagram for ultracool dwarfs. The binary components lie among the faintest and reddest planetary-mass L dwarfs. Credit: Best et al. 2017.

    So there is much to learn here. An object’s composition, temperature and formation history all come into play when determining whether it is a brown dwarf or a planet, and some definitions of brown dwarf take us below the 13 Jupiter mass criteria. But at 3.7 Jupiter masses, these objects clearly warrant the authors’ careful tag of “planetary mass binary.”

    The paper is Best et al., The Young L Dwarf 2MASS J11193254−1137466 Is a Planetary-mass Binary, Astrophysical Journal Letters Vol. 843, No. 1 (23 June 2017).

    Centauri Dreams


    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 3:13 pm on July 11, 2017 Permalink | Reply
    Tags: , , , Centauri Dreams, , Cornelia crater, , , Haulani Crater, Marcia crater, , Terrain Clues to Ice in the Outer System, The human expansion into the Solar System will demand our being able to identify sources of water, Vesta   

    From Centauri Dreams: “Terrain Clues to Ice in the Outer System” 

    Centauri Dreams

    July 11, 2017
    Paul Gilster

    The human expansion into the Solar System will demand our being able to identify sources of water, a skill we’re honing as explorations continue. On Mars, for example, the study of so-called ‘pitted craters’ has been used as evidence that the low latitude regions of the planet, considered its driest, nonetheless have a layer of underlying ice. The Dawn spacecraft discovered similar pitted terrain on Vesta, as you can see in the image below.

    NASA/Dawn Spacecraft

    1
    These enhanced-color views from NASA’s Dawn mission show an unusual “pitted terrain” on the floors of the craters named Marcia (left) and Cornelia (right) on the giant asteroid Vesta. The views show that the physical properties or composition of the material in which these pits form is different from crater to crater. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/JHUAPL.

    Vesta’s Marcia crater contains the largest number of pits on the asteroid. The 70-kilometer feature is also one of the youngest craters found there. So what accounts for this kind of terrain? Perhaps the water that formed the pits came from Vesta itself. Another possibility: Low-speed collisions with carbon-rich meteorites could have deposited hydrated materials on the surface, to be released in the heat of subsequent high-speed collisions within the asteroid belt. An explosive degassing into space could explain such pothole-like depressions.

    But Dawn wasn’t through when it left Vesta, and what it has found at Ceres is proving invaluable at understanding what appears to be a common marker of volatile-rich material. In new work from Hanna Sizemore [Geophysical Reseach Letters] (Planetary Science Institute) and colleagues, we learn that Ceres is home to the same kind of pitted terrain. As Sizemore notes:

    “Now, we’ve found this same type of morphological feature on Ceres, and the evidence suggests that ice in the Cerean subsurface dominated the formation of pits there. Finding this type of feature on three different bodies suggests that similar pits might be found on other asteroids we will explore in the future, and that pitted materials may mark the best places to look for ice on those asteroids.”

    2
    Haulani Crater, Ceres, showing abundant pitted materials on the crater floor. Similar pitted materials have previously been identified on Mars and Vesta, and are associated with rapid volatile release following impact. Their discovery on Ceres indicates pitted materials may be a common morphological indicator of volatile-rich materials in the asteroid belt. Haulani Crater is 34 km in diameter. Color indicates topography. Credit: NASA/MPS/PSI/Thomas Platz.

    Sizemore’s team studied the formation of pitted craters on Ceres through numerical models that explored the role of water ice and other volatiles. The morphological similarities between the Ceres features and what has been found on Mars and Vesta are striking. With water ice evidently significant in pit development on two asteroids and a planet, similar terrains will be of clear interest for future missions in terms of in situ resource utilization.

    4
    Pitted terrain on Mars as seen by HiRISE aboard the Mars Reconnaissance Orbiter. Credit: NASA/JPL/University of Arizona.

    Centauri Dreams


    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 4:40 pm on July 4, 2017 Permalink | Reply
    Tags: , , , Centauri Dreams, ,   

    From Centauri Dreams: “M-Dwarf Habitability: New Work on Flares” 

    Centauri Dreams

    July 4, 2017
    Paul Gilster

    The prospects for life around M-dwarf stars, always waxing and waning depending on current research, have dimmed again with the release of new work [Accepted in ApJ]from Christina Kay (NASA/GSFC) and colleagues. As presented at the National Astronomy Meeting at the University of Hull (UK), the study takes on the question of space weather and its effect on habitability.

    We know that strong solar flares can disrupt satellites and ground equipment right here on Earth. But habitable planets around M-dwarfs — with liquid water on the surface — must orbit far closer to their star than we do. Proxima Centauri b, for example, is roughly 0.05 AU from its small red host (7,500,000 km), while all seven of the TRAPPIST-1 planets orbit much closer than Mercury orbits the Sun. What, then, could significant flare activity do to such vulnerable worlds?

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    ESO Red Dots Campaign

    ESO Pale Red Dot project

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile interior

    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile

    1
    Artist’s impression of HD 189733b, showing the planet’s atmosphere being stripped by the radiation from its parent star. Credit: Ron Miller.

    Working with Merav Opher and Marc Kornbleuth (both at Boston University), Kay has homed in on coronal mass ejections (CMEs), the vast upheavals that throw stellar plasma into nearby space. While red dwarf stars are significantly cooler than our G-class Sun, their CMEs are thought to be far stronger because of their enhanced magnetic fields. From the paper:

    “Stellar activity tends to increase with the size of the stellar convection envelope (West et al. 2004) and stellar rotation rates (Mohanty et al. 2002; West et al. 2015), although the activity saturates for sufficiently high rotational velocity (Delfosse et al. 1998). For mid- to late-type M dwarfs (M4 to M8.5) the activity saturates at higher rotational velocities than for early-type M dwarfs, and above M9 the activity levels decrease significantly (Mohanty et al. 2002). Accordingly, most M dwarf stars will have significantly enhanced stellar activity as compared to the Sun.”

    A strong planetary magnetic field could counteract at least some of the resulting flare activity, but even there a possibility of strong erosion of the atmosphere remains. And if the planet is tidally locked, some recent work suggests little to no magnetic field can be expected.

    The paper outlines the process when a CME hits a nearby planet. One problem is extreme ultraviolet and X-ray flux (XUV) which can heat the upper atmosphere and perhaps ionize it. If such radiation gets through to the surface, it can damage any potential life-forms there. While it turns out that an M-dwarf habitable zone planet receives an order of magnitude less XUV flux than Earth when the star is quiet, the flux jumps as high as 100 times Earth’s during the star’s frequent flare activity.

    Significant CME activity also makes the planet much less likely to retain its atmosphere as a shield for life on the surface. A CME compresses whatever magnetosphere the planet has, and in extreme cases, say the authors, can exert enough pressure to shrink the magnetosphere to the point where the atmosphere can be seriously eroded.

    Modeling an Astrospheric Current Sheet

    Kay’s team modeled the effects of theoretical CMEs on the red dwarf V374 Pegasi, using a tool Kay developed for CME modeling called ForeCAT. They found that the strong magnetic fields of the star produce CMEs that can reach the so-called Astrospheric Current Sheet, where the background magnetic field is at its minimum. The same effect occurs with our Sun, when solar CMEs are deflected by magnetic forces toward the minimum magnetic energy.

    At the Sun, the Heliospheric Current Sheet — the local analog to a different star’s Astrospheric Current Sheet — is a field that extends along the Sun’s equatorial plane in the heliosphere and is shaped by the effect of the Sun’s rotating magnetic field on the plasma in the solar wind. The HCS separates regions of the solar wind where the magnetic field points toward or away from the Sun.

    Let’s dwell on that for a moment. Here’s what a NASA fact sheet has to say about the Heliospheric Current Sheet:

    “The sun’s magnetic field permeates the entire solar system called the heliosphere. All nine planets orbit inside it. But the biggest thing in the heliosphere is not a planet, or even the sun. It’s the current sheet — a sprawling surface where the polarity of the sun’s magnetic field changes from plus (north) to minus (south). A small electrical current flows within the sheet, about 10−10 A/m². The thickness of the current sheet is about 10,000 km near the orbit of the Earth. Due to the tilt of the magnetic axis in relation to the axis of rotation of the sun, the heliospheric current sheet flaps like a flag in the wind. The flapping current sheet separates regions of oppositely pointing magnetic field, called sectors.”

    3
    The Heliospheric Current Sheet results from the influence of the Sun’s rotating magnetic field on the plasma in the interplanetary medium (solar wind). The wavy spiral shape has been likened to a ballerina’s skirt. The new work uses a software modeling package called ForeCAT to study interactions between CMEs and the Astrospheric Current Sheet around the red dwarf V374 Pegasi. Credit: NASA GSFC.

    Kay and team have modeled the Astrospheric Current Sheet expected to be found around M-dwarfs like V374 Pegasi. The authors find that upon reaching the ACS, CMEs become ‘trapped’ along it. Planets can dip into and out of the ACS as they orbit. A CME moving out into the Astrospheric Current Sheet around an M-dwarf can cancel out a habitable zone planet’s local magnetic field, opening the world to devastating flare effects. The upshot:

    “We expect that rocky exoplanets cannot generate sufficient magnetic field to shield their atmosphere from mid-type M dwarf CMEs… We expect that the minimum magnetic field strength will change with M dwarf spectral type as the amount of stellar activity and stellar magnetic field strength change, and that early-type M dwarfs would be more likely to retain an atmosphere than mid or late-type M dwarfs.”

    The authors calculate that a mid-type M-dwarf planet would need a minimum planetary magnetic field between tens to hundreds of Gauss to retain an atmosphere, values that are far higher than Earth’s (0.25 to 0.65 gauss). CME impacts as numerous as five per day could occur for planets near the star’s Astrospheric Current Sheet. The only mitigating factor is that the rate decreases for planets in inclined orbits. The paper notes:

    “The sensitivity to the inclination is much greater for the mid-type M dwarf exoplanets due to the extreme deflections to the Astrospheric Current Sheet. For low inclinations we find a probability of 10% whereas the probability decreases to 1% for high inclinations. From our estimation of 50 CMEs per day, we expect habitable mid-type M dwarf exoplanets to be impacted 0.5 to 5 times per day, 2 to 20 times the average at Earth during solar maximum. The frequency of CME impacts may have significant implications for exoplanet habitability if the impacts compress the planetary magnetosphere leading to atmospheric erosion.”

    So we have much to learn about M-dwarfs. In particular, how accurate is the ForeCAT model in developing the CME scenario around such stars? As we examine such modeling, we have to keep in mind that magnetic field strength will change with the type of M-dwarf we are dealing with. Based on this research, only early M-dwarfs are likely to maintain an atmosphere.

    The paper is Kay, Opher and Kornbleuth, Probability of CME Impact on Exoplanets Orbiting M Dwarfs and Solar-Like Stars.

    Centauri Dreams

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
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