by Paul Gilster | Jun 15, 2012 | Outer Solar System |
What is it that makes us want the stars? Surely there are philosophical reasons that push us into the universe, and in his book Quest: The Essence of Humanity (2004), Charles Pasternak delves into ‘questing’ as a drive embedded in the species. But alongside a need to explore I can see two other drivers. One is the urge to know whether life exists elsewhere, and ultimately, whether there are other technological civilizations somewhere in the galaxy. The other is simple survival: We need to move into the universe as a backup plan in case of disaster here on Earth, whether that disaster is caused by an asteroid or a human activity gone awry.
This morning I’m musing on all this in the context of recent news from the outer Solar System, where the data we’re analyzing from the Cassini mission are matched only by our desire to have still further, more targeted explorations. We learn, for example, that Titan has lakes around its equator. Lakes on Titan aren’t a surprise: We’ve already known about lakes of methane and ethane like Ligeia Mare near the moon’s poles. But now we have evidence of a 2400 square kilometer body of liquid with a depth of a meter or more in Titan’s lower latitudes, down in the moon’s ‘tropics,’ where it was thought nothing but sand dunes were likely to be found.
Image: Saturn’s rings lie in the distance as the Cassini spacecraft looks toward Titan and its dark region called Shangri-La, east of the landing site of the Huygens Probe. Credit: NASA/JPL-Caltech/Space Science Institute.
This is a world that gets more interesting all the time. Titan draws our attention not only because of its thick atmosphere — which, coupled with low gravity, makes landing on it a straightforward affair — but also because its methane replaces water in Earth’s hydrological cycle to make it the only other place in the Solar System known to support liquid lakes. The newly found lakes, detected by Cassini’s visual and infrared mapping spectrometer, are found in the area called Shangri-La, not far from where the Huygens probe touched down in 2005. I hadn’t realized a point this NASA news release makes, that when Huygens landed, the heat of its lamp vaporized methane from the ground, an indication that the probe landed in a relatively damp area.
This week’s Nature has the paper, which reports not only on the larger lake but on small, evidently shallow ponds in the same region that can be likened to marshes on Earth, perhaps no more than ankle-deep. Current thinking on Titan’s global circulation had led us to believe that liquid methane in the equatorial regions would quickly evaporate and be carried by the winds to the poles, where it would condense to form the polar lakes, leaving the tropical regions arid. That model would suggest that the tropical lakes are being produced by an underground methane source that floods the surface, forming a kind of oasis.
Caitlin Griffith (University of Arizona) is lead author on the paper:
“An aquifer could explain one of the puzzling questions about the existence of methane, which is continually depleted. Methane is a progenitor of Titan’s organic chemistry, which likely produces interesting molecules like amino acids, the building blocks of life.”
The theory of an underground aquifer is also supported by the fact that rain has been detected falling in the equatorial regions only once, leading the researchers to believe the lakes are not being replenished by rain. Thus we are building the case for an active subsurface hydrology on the frigid moon as liquid hydrocarbons emerge on the surface to supply methane. The former image of equatorial Titan as a place of nothing more than sand dunes has to be reconsidered. Titan thus builds its reputation as a place of intriguing chemistry on which we’d like to spend some time, perhaps through an airborne probe like AVIATr or the floating Titan Mare Explorer.
Meanwhile, Cassini continues to return interesting information about another world of astrobiological interest, Enceladus. The latest is the observation of so-called ‘dusty plasma’ near the plumes spreading out from the moon’s south polar region. Saturn’s plasma environment is a lively one as Enceladus continues to spew ionized material into the planet’s magnetic field. About 100 kilograms of water vapor per second are known to be blowing out of the so-called ‘tiger stripes’ that mark the cracked surface of the south pole here. The plume is quickly converted into charged particles interacting with the plasma in Saturn’s magnetosphere.
‘Dusty plasma’ is filled with charged dust. Here, the dust behaves as part of the plasma cloud, differentiating it from dust that simply happens to be in the plasma at the time. Lead author Michiko Morooka (Swedish Institute of Space Physics) thinks the observation is a first:
“Such strong coupling indicates the possible presence of so-called ‘dusty plasma’, rather than the ‘dust in a plasma’ conditions which are common in interplanetary space. Except for measurements in Earth’s upper atmosphere, there have previously been no in-situ observations of dusty plasma in space.”
The work follows up on studies by Sven Simon (University of Cologne) and Hendrik Kriegel (University of Braunschweig) — reported in this JPL news release — that showed negatively charged dust grains had to be in the plume to account for the observed perturbation of Saturn’s magnetic field. The plume itself, known to contain water vapor, ice particles and organic molecules, presumably flags the presence of a subsurface ocean in which the basic ingredients for life to get a start may well be present. Mission concepts like the Enceladus Explorer, from the German Aerospace Center, would use a drilling probe to reach the liquid water reservoir.
The question of life in the universe is deeply stirring and compels us to search nearby worlds to learn whether life could have evolved under dramatically different conditions than here on Earth. Ultimately, our SETI efforts are directed toward slaking the same thirst for knowledge as we try to find out whether intelligence — or at least technological savvy — is common or a rare feature of the universe. Missions are always at the mercy of available resources and budgetary constraints, but the long-term forces of curiosity and survival compel us out into the system. Timetables are useless, but it’s hard to see these drivers being ignored by future generations.
The Titan paper is Griffith et al., “Possible tropical lakes on Titan from observations of dark terrain,” Nature 486 (14 June 2012), pp. 237-239 (abstract). On the Enceladus plasma work, see Morooka et al., “Dusty plasma in the vicinity of Enceladus,” Journal of Geophysical Research (Space Physics), Vol. 116 (2011), A12221 (abstract).
by Paul Gilster | Jun 14, 2012 | Exoplanetary Science |
In astronomy, the word ‘metals’ refers to anything heavier than hydrogen and helium. Stars fuse hydrogen into helium and from there work their way into the higher elements until hitting iron, at which point the end quickly comes, with ‘star stuff,’ as Carl Sagan liked to put it, being flung out into the universe. Through stellar generations we can trace a higher concentration of the heavier elements as stars are born from the materials of their predecessors. And we’ve learned that those metal-rich stars are the most likely to produce gas giants like Jupiter and Saturn.
What’s intriguing is the issue of smaller planets and the conditions for their formation. After all, the content of the disk from which planets are formed parallels the metallicity of the host star. I’m looking at new research from Lars A. Buchhave (Niels Bohr Institute/University of Copenhagen) into planet formation, using data from the Kepler telescope. In Buchhave’s words:
“We have analysed the spectroscopic elemental composition of the stars for 226 exoplanets. Most of the planets are small, i.e. planets corresponding to the solid planets in our solar system or up to four times the Earth’s radius. What we have discovered is that, unlike the gas giants, the occurrence of smaller planets is not strongly dependent on stars with a high content of heavy elements. Planets that are up to four times the size of Earth can form around very different stars – also stars that are poorer in heavy elements.”
Buchhave and team focused on whether small, Earth-like planets needed the same kind of metal-rich environment demanded by the gas giants, at least those with short orbital periods. Given that planets like the Earth are made up of heavier elements — iron, silicon, oxygen, magnesium — you would assume that small planet formation would be much more efficient around metal-rich stars. The new paper, which has been published in Nature, argues that the idea is wrong, and that opens up a lot of territory. Without special requirements for heavy elements in their stars, Earth-like planets could indeed be widespread in the galaxy.
Image: This artist’s conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Debris coalesces to create rocky ‘planetesimals’ that collide and grow to eventually form planets. The results of this study show that small planets form around stars with a wide range of heavy element content, suggesting that their existence might be widespread in the galaxy. Credit: University of Copenhagen/Lars Buchhave.
The work also implies that small planets could form earlier in galactic history than has previously been thought. Buchhave’s work examines this through the study of the spectroscopic metallicities of the host stars of the 226 Kepler candidates chosen. The average metallicity for planets smaller than four Earth radii turns out to be close to that of the Sun, but Buchhave says in this NASA news release that stars with just 25 percent of the Sun’s metallicity can also form small planets. Meanwhile the data continue to support the preferential formation of gas giants around higher metallicity stars.
From Natalie Batalha (NASA Ames), a member of the Kepler science team:
“Kepler has identified thousands of planet candidates, making it possible to study big-picture questions like the one posed by Lars. Does nature require special environments to form Earth-size planets? The data suggest that small planets may form around stars with a wide range of metallicities — that nature is opportunistic and prolific, finding pathways we might otherwise have thought difficult.”
Indeed. We are learning that it doesn’t take that many generations of stars to start producing rocky worlds. The work was presented yesterday at the 220th meeting of the American Astronomical Society. “Giant planets prefer metal-rich stars. Little ones don’t,” says David Latham (Harvard-Smithsonian Center for Astrophysics). The CfA’s own news release says the work supports the core accretion view of planet formation, in which steadily accumulating planetesimals combine to form planets, with the largest quickly gathering hydrogen. Higher metallicities make quick formation of large cores more likely, which explains the connection between heavier metals and gas giants.
Are there SETI implications here as well? This from Jill Tarter (SETI Institute):
“The idea that very old stars could also sport habitable planets is encouraging for our searches. In particular, intelligent life has taken a long time to evolve here on Earth. Consequently, it’s reasonable to suppose that older planetary systems are more likely to have technological societies – the kind we might detect with our radio telescopes.”
And that reminds me to note that the SETI Institute is hosting SETIcon II in Mountain View, California from June 22-24, where those in attendance can rub elbows with the likes of Geoff Marcy and Debra Fischer. I see that tickets are still available to the public.
The paper is Buchhave et al., “An abundance of small exoplanets around stars with a wide range of metallicities,” published online in Nature 13 June 2012 (abstract).
by Paul Gilster | Jun 13, 2012 | Deep Sky Astronomy & Telescopes |
by Dr. Gregory L. Matloff
Gregory Matloff is a major figure in what might be called the ‘interstellar movement,’ the continuing effort to analyze our prospects for travel to the stars. Greg is Emeritus Associate Professor and Adjunct Associate Professor in the Department of Physics at New York City College of Technology as well as Hayden Associate at the American Museum of Natural History. Centauri Dreams readers will know him as the author (with Eugene Mallove) of The Starflight Handbook (Wiley, 1989) and also as author or co-author of recent books such as Deep Space Probes (2005), Living Off the Land in Space (2007) and Solar Sails: A Novel Approach to Interplanetary Travel (2010). My own acquaintance with Greg’s work began with the seminal JBIS paper “Solar Sail Starships: The Clipper Ships of the Galaxy” (1981), and the flow of papers, monographs and books that followed have set high standards for those investigating our methods for going to the stars, and the reasons why we should make the attempt.
In the summer of 2011, Dr. Matloff delivered a paper in London at the British Interplanetary Society’s conference on the works of philosopher and writer Olaf Stapledon, the author of Star Maker (1937). One of Stapledon’s startling ideas was that stars themselves might have a form of consciousness. Greg’s presentation went to work on the notion in light of anomalous stellar velocities and asked what might make such an idea possible. His paper on the seemingly incredible notion follows. –PG
ABSTRACT
The Dark Matter hypothesis has been invoked as an explanation for the fact that stars revolve around the centers of their galaxies faster than can be accounted for by observable matter. After decades of failed experimental searches, dark matter has remained elusive. As an alternative to the Dark Matter hypothesis, a idea first presented by author Olaf Stapledon is developed in this paper. Stars are considered to be conscious entities maintaining their galactic position by their volition. It is shown that directed stellar radiation pressure and stellar winds are insufficient to account for this anomalous stellar velocity. Previous research rules out magnetism. A published theory of psychokinetic action that does not violate quantum mechanics is discussed, as is the suggestion that stellar consciousness could be produced by a Casimir effect operating on molecules in the stellar atmosphere. It is shown that a discontinuity in stellar velocities as a function of spectral class exists. Cooler red stars in the solar neighborhood move faster than hotter, blue stars, as would be expected if the presence of molecules in stars was a causative factor. Further research in experimentally validating the psychokinetic effect and demonstrating the role of the Casimir effect in consciousness is required to advance the concepts presented here beyond the hypothesis stage.
Introduction: Elusive Dark Matter
The motions of our Sun and other stars around the centers of their galaxies cannot be fully accounted for the presence of observable stellar or non-stellar matter. Possible modifications to Einstein-Newton gravitation do not seem appropriate since general relativity has easily passed every experimental test to date. Cosmologists hypothesize the existence of a non-reactive, non-observable but gravitating substance dubbed “dark matter” to account for the discrepancy. Dark matter seems to out-mass ordinary matter, according to many estimates [1].
But science requires observation or experimental validation for even the most beautiful of theoretical constructs. The continuing failure to detect or observe candidate dark matter objects or particles presents astrophysics with a very serious anomaly. Perhaps, as was the case in the late 19th century with the failure to confirm the ether hypothesis, the solution to the dark matter paradox may require a change in paradigm.
Image: Gregory Matloff (left) being inducted into the International Academy of Astronautics by Ed Stone.
Here, we reintroduce a 1937-vintage hypothesis of the British philosopher/science-fiction author Olaf Stapledon. In his monumental visionary novel Star Maker, Stapledon develops the thesis that stars are conscious and their motions around the galactic center are due to voluntary stellar adherence to the canons of a cosmic dance [2]. This is admittedly an extraordinary hypothesis. But if dark matter remains elusive and undetected no matter how expensive and elaborate the equipment seeking it, exotic alternatives cannot be dismissed out of hand.
Stellar Kinematics
Kinematics arguments presented here are elementary. Because of the low velocities (relative to the speed of light in vacuum), Newtonian dynamics is assumed. The reference frame is centered on the center of the Milky Way galaxy.
Following Newton’s Second Law, force is defined:
F = MA
where M = mass and A = acceleration. Linear momentum is defined:
P = MV
where V= a star’s orbital velocity around the galactic center and kinetic energy is defined as:
KE = 0.5MV2
The Sun revolves around the center of the Milky Way galaxy at ~220 km/s [3]. Let us posit that a solar-type star must alter its velocity by 100 km/s in 109 years by applying a non-gravitational force. This amounts to an acceleration of ~3 X 10-12 m/s2 or about ~3 X 10-13 g.
A solar-type star has a mass of about 2 X 1030 kg [5]. The (assumed) constant value of the non-gravitational force is about 6 X 1017 Newtons. While this seems like a huge force, it is roughly a million times less than the Sun’s gravitational force on the Earth.
Another means of considering this force’s magnitude is to assume that a 100-kg human is able to produce the same acceleration on herself during a 100-year lifetime. The average magnitude of this force on the human is about 3 X 10-10 N. During the person’s life, the force alters her velocity by about 0.01 m/s or 1 cm/s. This is far below the threshold of detection.
But what might be the cause of this elusive stellar force? Magnetism has been ruled out, at least for many astrophysical objects [4]. So we can consider two other physical candidates—a directed stellar wind and a unidirectional radiation pressure force.
Assume that a star can generate a continuous, unidirectional flux of ionized particles. The velocity of this “jet” is the typical solar wind velocity of 400 km/s. By the Conservation of Linear Momentum, the star must expel one-quarter of its mass in the uni-directional jet to alter its galactic velocity by 100 km/s. Such an astronomical event has never been observed and would be very disconcerting (most fatal) if it occurred on the Sun. The solar wind of ionized particles is clearly inadequate to alter a star’s velocity by 100 km/s.
Now let’s see if the radiation pressure on the star produced by its radiant output could produce a velocity change of 100 km/s in a billion years, if all the solar electromagnetic flux was concentrated in a narrow beam. If the star’s mass is equal to that of the Sun—2 X 1030 kg [5], the required change in stellar linear momentum amounts to about 7 X 1018 kg-m/s. If the star has a solar radiant output of about 4 X 1026 watts [5] and we apply the standard equation for a photon’s momentum (P) [6],
P = E/C
where E is the photon energy and c is the speed of light, we see that the total maximum radiation-pressure-induced linear-momentum change on the star is about 1.3 X 1018 kg-m/s. A star can clearly not affect the required linear momentum change in this fashion.
Magnetism, particle flow, and photon flow all fail to produce the required alteration in star kinematics. But there is at least one theoretical possibility that remains.
The Psychokinetic Option
One physically possible explanation for anomalous stellar motion is psychokinesis. The hypothesis is here presented that the “mind” of a conscious or sentient star can act directly upon the physical properties (in this case the galactic velocity) of that star.
Although no claim is made that psychokinesis (PK) is part of mainstream physics or psychology, at least one serious theoretical study indicates that it is possible within the currently accepted framework of quantum mechanics [7].
According to the arguments presented in Ref. 7, consciousness (or “mind”) can directly influence the properties of a physical system by utilizing the energy present in quantum mechanical fluctuations. Consciousness may do this by affecting collapse of the wave function of the system to the desired quantum state.
Such anomalous phenomena as alteration in the output of random number generators and levitation could be explained by such a process [7]. Although energy is conserved in this model of PK, the authors of Ref. 7 acknowledge possible violations of the second law of thermodynamics.
If a 2 X 1030 kg star changes its velocity by (a somewhat arbitrary) 100 km/s in a 109 year time interval using this technique, its kinetic energy changes by 1040 Joules and the average power required for the stellar velocity change is about 3 X 1023 watts. This is about 0.1% of the Sun’s radiant output.
In order to demonstrate that such a process could be applicable to stars, it is necessary to present arguments that at least some stars are conscious. Perhaps a good place to start is to consider what some researchers have said about consciousness in humans and other life forms.
Consciousness in Humans, Animals, Plants and Stars
Defining consciousness is not easy. We are all rather certain of our own consciousness and relatively convinced that other humans are conscious as well. Most would agree that whales, dolphins, chimps, cats and dogs are conscious organisms as well. But how about snakes, corn, amoeba, and bacteria? Do in fact the mechanisms that support consciousness in the higher animals, in fact, require billions of years of organic evolution to develop? Or does consciousness in some form permeate the entire universe?
Some, like Walker, conclude that consciousness cannot be defined. Instead, it must be thought of as the immediate experience of the world around us and our internal thoughts and emotions [8]. Bohm believes that conscious thought is a process rather than an object [9]. Kafatos and Nadeau argue that this process in some perhaps pantheistic sense permeates the entire universe [10]. Many theories have developed to fit this elusive phenomenon into the framework of physical science. Some are reviewed and developed in Refs. 11 and 12.
The concepts developed in this paper accept that consciousness, like gravitation, is built into the structure of the universe [10]. Like gravitation, it cannot be explained by invoking fields or matter independently but requires the interaction of both.
Many of the quantum-physics-based theories of organic consciousness postulate that a universal consciousness field interacts with electrically conducting nanostructures within the cell or nervous system. In higher animals (such as humans) the ~20-nm inter-synaptic spacing in the brain’s neuronal structure have been suggested and analyzed by Evan Harris Walker as locations of the quantum-level events contributing to consciousness [13]. But all living eukaryotic cells contain microtubules. As suggested by Lynn Margolis, a form of “microbial consciousness” may be centered upon these nano-structures [14].
Various quantum phenomena within these nanostructures have been suggested as the primary “active agents” of consciousness. These include quantum tunneling [13], quantum entanglement [15], and the Casimir Effect [16]. It is known that the Casimir Effect—a pressure caused by vacuum fluctuations—is a component of molecular bonds [17].
We propose the following Casimir-Effect approach to stellar consciousness. It is assumed that the interaction with vacuum fluctuations produces a form of consciousness in all molecular bonds, although this is weaker than the forms of consciousness affected by the interaction of vacuum fluctuations with organic nanostructures such as microtubules and the inter-synaptic spacing. Admittedly this is a pantheistic approach to the universe. All molecules to a certain extent are conscious. Stars cool enough to contain stable molecules are therefore conscious, at least to some extent. Over a very long period of time, they can apply psychokinetic effects to maintain their galactic position and remove at least some of the requirement for the thus-far undetected dark matter.
Some Evidence Supporting the Hypothesis of Conscious Stars
The ideas presented above might fit in the realms of philosophy and science fiction rather than physics unless there were some observational supporting evidence. A literature search was conducted to determine whether there is a kinematical discontinuity in stellar proper motion depending upon star surface temperature and occurring in the stellar spectral classes for which molecular lines and bands appear.
Since the 1950’s, such a discontinuity has in fact been recognized. Dubbed Parenago’s discontinuity, it refers to the fact that red, cooler stars have faster motions in the direction of galactic rotation than do blue, cooler stars. Figure 1 presents from two sources a plot of the solar motion of main sequence stars versus star B-V color index [18, 19]. The data set from Binney et al is derived from Hipparcos observations of more than 5,000 nearby stars [19].
Table 1 presents the spectral types corresponding to the B-V color indices on the abscissa of Fig. 1 [20]. The Parenago discontinuity occurs at around (B-V) = 0.6, which corresponds to early G dwarf stars such as the Sun. Note that estimated main sequence residence times for various spectral classes are also given in Table 1 [21].
TABLE 1 B-V Color Indices, Corresponding Spectral Classes and Main Sequence Residence Times for Dwarf Stars
Binney et al [19] present the hypothesis that the faster galactic velocities of cool, red, long-lived stars is due to the fact that gravitational scattering causes a star’s velocity to increase with age. This seems unlikely since F0 stars reside on the main sequence for a few billion years. In the Sun’s galactic neighborhood, stellar encounters close enough to alter stellar velocities are very rare due to the large star separations involved. For stellar encounters to cause Parenago’s discontinuity, these would likely occur while the stars were resident in the open cluster from which they originated. Since open clusters disperse within a few hundred million years [1], such stellar encounters seem to be an unlikely explanation for Parenago’s discontinuity.
The explanation presented here is based upon telescopic observations of molecules in the spectra of stars of various spectral classes. Molecules are rare or non-existent in the spectra of hot, blue stars. As star radiation temperature decreases, molecular signatures in stellar spectra become more apparent. In dwarf stars, N2 rises in abundance as photosphere temperature falls below 6000 K [22]. The spectral signature of CO is present in the Sun’s photosphere [23]. As stellar photosphere temperatures fall to around 3200 K (M2 stars), spectral signatures of many molecules including TiO and ZrO become observable in the infrared spectra [23].
Conclusions
Although it is provocative that Parenago’s stellar velocities around the galactic center increase with molecular abundance in the stellar photosphere, this paper does not claim to prove stellar consciousness as an alternative to dark matter. There are many other more conventional alternative explanations for anomalous stellar kinematics that must be considered as well [24].
But the validity of some of the assumptions presented here will be confirmed if future work demonstrates that PK effects can be reliably repeated in a laboratory environment. Other assumptions will be validated if future nano-scale computers achieve some level of consciousness when the size of computing elements reaches molecular levels.
If stellar consciousness can be demonstrated to be a reasonable dark matter alternative, major challenges will be presented to the SETI community. How exactly do we communicate with conscious, possibly sentient entities with lifetimes so long that a century seems like a second? And if we can’t do this successfully, how do we prevent the catastrophic wars between planetary and stellar intelligence in Star Maker as human interplanetary capabilities mature?
Some may argue in favor of Decartes’ separation of consciousness from the physical world. This approach is no longer valid at the molecular level since consciousness seems to be necessary for quantum mechanics and quantum mechanics is a well-validated physical theory [12].
Adam Crowl has pointed out to the author that the hypothesis presented here addresses one line of evidence for dark matter—the flatness of galactic rotation curves. A second line of evidence—observations that galactic clusters do not have enough visible mass to keep from dispersing—is not addressed by the arguments presented here [25].
Some may disagree with the inclusion of PK as a candidate “propulsion system” for conscious stars. As described in an excellent recent review by an MIT physics professor, this very controversial topic was investigated during the 1970’s by a distinguished group of theoretical physicists centered upon Stanford University. Debate still swirls regarding their courageous attempt to obtain mainstream support for their research [26].
Any scientific hypothesis must be falsifiable. The Hipparchos data used to prepare Ref. 19 utilized statistics for 5610 stars near the celestial south pole. According to the project’s website, the forthcoming ESA Gaia mission is planned to produce a kinematics census of a billion stars in the Milky Way galaxy. It will be interesting to learn whether this flood of data supports or refutes Parenago’s discontinuity.
Acknowledgements
The author appreciates the comments and suggestions of A. Crowl, which have been incorporated in the text. He is also grateful to K. Long who presented a version of this paper for him at the Nov. 23, 2011 Olaf Stapledon Symposium at BIS headquarters in London. Comments of anonymous referees are also appreciated.
References
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2. O. Stapledon, Last and First Men and Star Maker, Dover, NY (1968).
3. D. Scott, J. Silk, E. W. Kolb, and M. S. Turner, “Cosmology,” in Allen’s Astrophysical Quantities, 4th ed., ed. A. N. Cox, Springer-Verlag, NY (2000), Chap. 26.
4. F. J. Sanchez-Salcedo and M. Reyes-Ruiz, “Constraining the Magnetic Effects on HI Rotation Curves and the Need for Dark Halos,” Astrophysical Journal, 607, 247-257 (2004).
5. K. Lodders and B. Fegley Jr., The Planetary Scientist’s Companion, Oxford University Press, NY (1988).
6. A. Messiah, Quantum Mechanics, Wiley, NY (1958).
7. R. D. Mattuck and E. H. Walker, “The Action of Consciousness on Matter: A Quantum Mechanical Theory of Psychokinesis,” in The Iceland Papers, ed. A. Puharich, Essentia Research Associates, Amherst, WI (1979), pp. 111-160.
8. E. H. Walker, The Physics of Consciousness, Perseus Books, Cambridge, 8. MA (2000).
9. D. Bohm, Wholeness and the Implicate Order, Routledge & Kegan Paul, London, UK (1980).
10. M. Kafatos and R. Nadeau, The Conscious Universe, Springer-Verlag, NY (1990). Also see R. Penrose, The Emperor’s New Mind, Oxford University Press, NY(1989).
11. H. P. Stapp, Mind, Matter, and Quantum Mechanics, Springer-Verlag, NY (1993).
12. B. Rosenblum and F. Kuttner, Quantum Enigma: Physics Encounters Consciousness, Oxford University Press, NY (2006).
13. E. H. Walker, “The Nature of Consciousness,” Mathematical Biosciences, 7, 131-178 (1970).
14. L. Margulis, “The Conscious Cell,” in Cajal and Consciousness (Annals of the New York Academy of Sciences, Vol. 929), ed. P. C. Marijuan, pp. 55-70 (2001).
15. R. Penrose, “Quantum Computation, Entanglement and state Reduction,” Philosophical Transactions of the Royal Society, London A, 356, 1927-1939 (1998)..
16. B. Haisch, The God Theory, Weiser Books, San Francisco, CA (2006).
17. “Van der Waals Force,” www.wikipedia.org/wiki/Van_der_Waals_Force (accessed Oct. 22, 2011).
18. G. F. Gilmore and M. Zeilik, “Star Populations and the Solar Neighborhood,”” Allen’s Astrophysical Quantities, 4th ed., ed. A. N. Cox, Springer-Verlag, NY (2000), Chap. 19.
19. J. J. Binney, W. Dehnen, N. Houk, C. A. Murray and M. J. Preston, “The Kinematics of Main Sequence Stars from Hipparcos Data,” in Proceedings of the ESA Symposium ‘Hipparcos-Venice ’97,’ ESA SP-402, Venice, Italy 13-16 May 1997, pp. 473-477 (July, 1997).
20. J. S. Drilling and A. U. Landolt, “Normal Stars,” Allen’s Astrophysical Quantities, 4th ed., ed. A. N. Cox, Springer-Verlag, NY (2000), Chap. 15.
21. R. A. Freitas Jr., Xenology: An Introduction to the Scientific study of Extraterrestrial Intelligence and Civilization, 1st ed., Xenology Research Institute, Sacramento, CA (1979). http://www.xenology.info/xeno.htm.
22. L. H. Allen, “Interpretation of Normal Stellar Spectra,” Stellar Atmospheres, ed. J. L. Greenstein, Un1versity of Chicago Press, Chicago, ILL (1960), Chap. 5.
23. G. F. Sitnik and M. Ch. Pande, “Two Decay Processes for CO Molecules in the Solar Photosphere,” Soviet Astronomy, 11, 588-591 (1968).
24. S. Capozziello, L. Consiglio, M. De. Laurentis, G. De Rosa, and C. Di Donata, “The Missing Matter Problem: From the Dark Matter Search to Alternative Hypothesis,” arXiv:1110.5026v1 [astro-ph.CO] 23 Oct 2011.
25. A. Crowl, “Personal Communication” (Nov. 18, 2011).
26. D. Kaiser, How the Hippies Saved Physics, Norton, NY (2011).
by Paul Gilster | Jun 12, 2012 | Exoplanetary Science |
The success of the Kepler mission in sifting through a field of more than 150,000 stars to locate transiting planets is undeniable, and the number of planets thus far discovered has been used to estimate how often planets occur around stars like the Sun. Now comes a paper to remind us that statistical analysis based on Kepler results assumes that most of the planet candidates are real and not false positives. Alexandre Santerne, a graduate student at the University of Aix-Marseille, has worked with a team of researchers to study the false positive rate for giant planets orbiting close to their star. 35 percent of these Kepler candidates may be impostors.
The problem is that eclipsing binaries can mimic planetary transits, which is why scientists perform follow-up radial velocity studies or use transit timing variations (TTV) to confirm the existence of the planet. Another technique is to systematically exclude all possible false positive scenarios to a high level of confidence. Whatever the method, it’s clear that validating Kepler’s candidates — making sure that what looks like a planet really is one — has a key role to play if we’re going to interpret the Kepler results properly and extend them to the larger stellar population.
Image: Both Kepler and CoRoT have detected exoplanets by looking for the drop in brightness they cause when they pass in front of their parent star. But as transit studies continue, scientists are working to filter out false positives. Credit: CNES.
Santerne’s team used the SOPHIE spectrograph at Observatoire de Haute-Provence, looking at a selection of Kepler giant planet candidates for follow-up spectroscopic studies. Their sample of 46 candidates represented about 2 percent of the total list of 2321 candidates as of February 2012, and about 22 percent of the giant planet candidates with significant transit depth found thus far in the Kepler data. Their candidates all showed a transit depth greater than 0.4%, an orbital period less than 25 days and a host star brighter than Kepler magnitude 14.7.
Eleven of the candidates had already been confirmed as planets, and the researchers were able to confirm another nine. Two of the candidates turned out to be transiting brown dwarfs and another eleven were in binary star systems. All of that leaves 13 unconfirmed candidates, and leads the team to conclude that the false-positive rate for giant, close-in planets is 35 percent. It’s an interesting result in light of earlier work by Timothy Morton and John Johnson (Caltech), who calculated an expected false positive probability (FPP) of Kepler planets of 5 percent for most candidates.
Morton reacted to the new work in this article in Science News:
…comparisons between the two studies might not be so simple, Morton says, noting that the two groups calculated different things. Instead of looking at impostor rates in a specific population of planets, Morton determined the probability that any candidate — plucked from the sea of twinkling candidates — was real. He also excluded data from obvious impostors.
“Everything here is sort of a game of probabilities,” Morton says, pointing to the abundance of candidates. “It will be impossible to confirm them all with observations.”
The Santerne paper argues that Morton and Johnson did not consider undiluted eclipsing binaries — binary stars that mimic a close-in gas giant — as a source of false positives in the Kepler data, assuming that detailed analysis of Kepler photometry alone would be enough to weed these out. Santerne’s team disagrees:
…we have found that more than 10% of the followed-up candidates are actually low-mass-ratio binary stars, even excluding the two brown dwarfs reported here. This source of false positives is expected to be less important for smaller-radii candidates. However, as it is clearly shown by the cases of KOI-419 and KOI-698, stellar companions in eccentric orbits and with relatively long periods can produce single-eclipse light curves, even for greater mass ratios. It is difficult to imagine how these candidates can be rejected from photometry alone if grazing transits are to be kept.
In other words, it’s easier to mimic a planetary signature than we realized in the case of close-in giant planets. It will take radial velocity follow-up studies of giant planets on much wider orbits to determine whether the false positive rate is as high with them. And we have a lot to do to learn about the reliability of our smaller planet detections:
Only a small fraction of Kepler small candidates are suited for the radial velocity follow-up. These candidates should be followed in radial velocity to determine the true value of FPP and to fill the mass-radius diagram of Neptune and super-Earth like planets. This FPP value for small size candidates is required to correctly derive and discuss the distribution of transiting planet parameters.
The paper is Santerne et al., “SOPHIE velocimetry of Kepler transit candidates VI. A false positive rate of 35% for Kepler close-in giant candidates,” accepted by Astronomy & Astrophysics (preprint). Thanks to Antonio Tavani for the pointer to this one.
by Paul Gilster | Jun 11, 2012 | Deep Sky Astronomy & Telescopes |
Nobody has been anticipating the results from WISE — the Wide-field Infrared Survey Explorer — any more than I have. Speculations about the number of brown dwarfs in the galaxy have been all over the map, with some suggesting they might be as plentiful as M-dwarfs, which make up perhaps 80 percent of the stellar population. But the latest results from our infrared scan of the sky argue a much different result: Brown dwarfs turn out to be considerably more rare than stars, with an initial tally of the WISE data showing just one brown dwarf for every six stars.
Thus Davy Kirkpatrick, a member of the WISE science team at NASA’s Infrared Processing and Analysis Center at Caltech:
“This is a really illuminating result. Now that we’re finally seeing the solar neighborhood with keener, infrared vision, the little guys aren’t as prevalent as we once thought.”
Ouch. The nice thing about a sky full of undiscovered brown dwarfs was that it might serve up interstellar destinations closer than the Alpha Centauri stars. None has been discovered yet, and we’ll apparently have to travel a lot farther to move between average-spaced brown dwarfs than we once thought. Not that these stars — or ‘failed stars’ as they are called because they cannot sustain hydrogen fusion at the core — are not interesting in their own right. We’d like to learn how they form, and how they tread the fine line between planet and star.
Image (click to download a larger version): Our own back yard, astronomically speaking, from a vantage point about 30 light-years away from the sun. The image highlights the population of tiny brown dwarfs recently discovered by NASA’s Wide-field Infrared Survey Explorer, or WISE (red circles). The image simulates actual positions of stars. All brown dwarfs known within 26 light-years are circled. Blue circles are previously known brown dwarfs, and red circles are brown dwarfs identified for the first time by WISE. The slightly larger M-dwarf stars, which are the most common type of star in the solar neighborhood, are shown with enhanced brightness to make them easier to see. Image credit: NASA/JPL-Caltech.
WISE has already identified the class of brown dwarfs known as Y dwarfs, one example of which is more or less at room temperature (25 degrees Celsius), making it the coldest of all star-like bodies found. This JPL news release says that in its survey to this point, the WISE team can identify about 200 brown dwarfs in the Sun’s vicinity, including 13 of the Y dwarf category. 33 of these brown dwarfs as measured by parallax methods are within 26 light years of the Sun, while 211 other stars also exist within the same volume of space.
Chris Gelino, also at the Infrared Processing and Analysis Center, puts a positive spin on the matter:
“Having fewer brown dwarfs than expected in our celestial backyard just means that each new one we discover plays a critical role in our overall understanding of these cold objects. These brown dwarfs are fascinating objects that are bridging the gap between the coldest stars and Jupiter.”
True enough, but the chances of a brown dwarf closer than Proxima Centauri are rapidly fading, although discovering additional Y dwarfs could adjust the ratio of brown dwarfs upwards slightly, if not as high as once thought. And as the WISE data continue to be sifted for further brown dwarf information, we should also keep in mind that we’re still pretty much in the dark about the number of ‘rogue’ planets out there, moving through the interstellar night without any stellar companion. Planets as much as several times the mass of Jupiter could still be out there, too faint to show up in the WISE data but possible targets for future deep space probes.
For more on rogue stars, see Island-Hopping to the Stars, which examines the work of Louis Strigari (Stanford University). Here you’ll find his estimate that there may be up to 105 compact objects per main sequence star in the galaxy that are greater than the mass of Pluto. It’s an extraordinary figure, but a big part of Strigari’s work relies upon the idea that rogue planets (he calls them ‘nomads’) in open clusters follow the brown dwarf mass function, so it will be interesting to see how the WISE data may eventually affect his calculations.
