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Mass distribution and evolutionary scheme for central stars of planetary nebulae
IUE data and a distance measuring method that considered central stars in optically thick nebulae were used to examine mass distributions of planetary nebulae. Other data such as spectral type, spatial and kinematic characteristics, etc., were studied to derive relationships between population type and mass distribution. A central star mass range of at least 0.55 solar mass was obtained. Stars with masses of at least 0.64 solar mass, concentrated in the galactic disk, originated from 1.5 solar mass stars. Low mass nuclei originated in old disk or halo populations and evolved from 1.0 solar mass objects. A mass-loss parameter value of 1/3 was calculated for red giants, implying that white dwarfs evolve from stars of under 5 solar masses. Mass distributions around planetary nuclei were concluded to follow patterns associated with the individual mass.
MOA-2012-BLG-505Lb: A Super-Earth-Mass Planet that Probably Resides in the Galactic Bulge
We report the discovery of a super-Earth-mass planet in the microlensing event MOA-2012-BLG-505. This event has the second shortest event timescale of t(sub E) = 10 ± 1 days where the observed data show evidence of a planetary companion. Our 15 minute high cadence survey observation schedule revealed the short subtle planetary signature. The system shows the well known close/wide degeneracy. The planet/host-star mass ratio is q = 2.1 × 10(exp −4) and the projected separation normalized by the Einstein radius is s = 1.1 or 0.9 for the wide and close solutions, respectively. We estimate the physical parameters of the system by using a Bayesian analysis and find that the lens consists of a super-Earth with a mass of 6.7(sup +10.7)(sub -3.6) Mꚛ orbiting around a brown dwarf or late-M-dwarf host with a mass of 0.10(sup +0.16)(sub -0.05) Mꙩ with a projected star–planet separation of 0.9(sup +0.3)(sub -0.2) au. The system is at a distance of 7.2 ± 1.1 kpc, i.e., it is likely to be in the Galactic bulge. The small angular Einstein radius (θ(sub E) = 0.12 ± 0.02 mas) and short event timescale are typical for a low-mass lens in the Galactic bulge. Such low-mass planetary systems in the Bulge are rare because the detection efficiency of planets in short microlensing events is relatively low. This discovery may suggest that such low-mass planetary systems are abundant in the Bulge and currently ongoing high cadence survey programs will detect more such events and may reveal an abundance of such planetary systems.
Feasibility and Performance Analysis of Magnetohydrodynamic Control for Aerocapture at Neptune
Throughout the past few decades, the demand for farther and more massive missions have increased significantly, especially with the recent push for manned missions to Mars as well as the growing sci- entific interest in the outer giant planets and their re- spective moons. While spacecraft have successfully made it to the surface of Mars and into a flyby of the outer planets, the technologies from these missions are reaching the threshold of their capabilities. These tradi- tional methods are inadequate for higher mass and outer planetary missions due to the inherent propellant mass constraints of using fully-propulsive orbital insertion. Thus, there has been an ongoing effort to introduce new methods of deceleration and flight control during plan- etary EDL to reduce the required orbital insertion pro- pellant mass and enable new missions. One of the most prominently proposed solutions is aerocapture.
Improved ion sources
Ion sources with magnetically aligned electron beam and compatibility with quadrupole mass spectrometer for planetary atmospheric analysis
Compact Two-step Laser Time-of-Flight Mass Spectrometer for in Situ Analyses of Aromatic Organics on Planetary Missions
RATIONALE A miniature time-of-flight mass spectrometer has been adapted to demonstrate two-step laser desorption-ionization (LOI) in a compact instrument package for enhanced organics detection. Two-step LDI decouples the desorption and ionization processes, relative to traditional laser ionization-desorption, in order to produce low-fragmentation conditions for complex organic analytes. Tuning UV ionization laser energy allowed control ofthe degree of fragmentation, which may enable better identification of constituent species. METHODS A reflectron time-of-flight mass spectrometer prototype measuring 20 cm in length was adapted to a two-laser configuration, with IR (1064 nm) desorption followed by UV (266 nm) postionization. A relatively low ion extraction voltage of 5 kV was applied at the sample inlet. Instrument capabilities and performance were demonstrated with analysis of a model polycyclic aromatic hydrocarbon, representing a class of compounds important to the fields of Earth and planetary science. RESULTS L2MS analysis of a model PAH standard, pyrene, has been demonstrated, including parent mass identification and the onset o(tunable fragmentation as a function of ionizing laser energy. Mass resolution m/llm = 380 at full width at half-maximum was achieved which is notable for gas-phase ionization of desorbed neutrals in a highly-compact mass analyzer. CONCLUSIONS Achieving two-step laser mass spectrometry (L2MS) in a highly-miniature instrument enables a powerful approach to the detection and characterization of aromatic organics in remote terrestrial and planetary applications. Tunable detection of parent and fragment ions with high mass resolution, diagnostic of molecular structure, is possible on such a compact L2MS instrument. Selectivity of L2MS against low-mass inorganic salt interferences is a key advantage when working with unprocessed, natural samples, and a mechanism for the observed selectivity is presented.
The MASSE Project: Applications of Biotechnology for Planetary Exploration
Automated life-detection experiments for solar system exploration have been previously. proposed and used onboard the. Viking, Mars lander,s, although. with ambiguous results. The recent advances in biotechnology such as biosensors, protein microarrays, and microfluidics alongside increased. knowledge in biomarker science have led to vastly improved sophistication and sensitivity for a new approach in life detection. The MASSE project has taken the challenge of integrating all of this knowledge into a new generation of interplanetary flight instrumentation for the main purpose.ot combining several mutually. confirming tests for life, organic/microbial contamination, prebiotic and abiotic chemicals into a small low powered instrument. Although the primary goal is interplanetary exploration, several terrestrial applications have become apparent specifically in point-of-care medical technology, bio-warfare, environmental sensing and microbial monitoring of manned space-flight vehicles.
The Contribution of Planetary Period Oscillations Toward Circulation and Mass Loss in Saturn's Magnetosphere
Magnetic reconnection is a process during which magnetic energy is released as kinetic energy. It is considered a crucial driver of energy transport and mass loss within Saturn's magnetosphere. On longterm timescales, is thought to be predominantly driven by the rapid rotation of equatorially mass-loaded flux tubes (i.e., the Vasyliunas cycle), but there is some non-negligible driving from the solar wind as well (i.e., the Dungey cycle). In this study, we investigate an atmospheric driven phenomenon that modulates Saturn's magnetosphere every ∼10.6–10.8 hr, known as planetary period oscillations (PPOs), as an additional driver of magnetic reconnection at Saturn. Using an empirical model of PPO dynamics and Cassini magnetic field and plasma measurements, we find that PPO-driven magnetic reconnection is likely to occur in Saturn's magnetosphere, however, the occurrence of the phenomenon depends on temporally variable characteristics of the PPO systems and spatial asymmetries within Saturn's equatorial magnetosphere. Thus, it is not expected to be an on-going process. On year-long timescales, we find that PPOs are expected to be on par with the Dungey Cycle in driving circulation within Saturn's magnetosphere. However, on ∼1–2 weeks-long timescales, under specific conditions where PPO-driven reconnection is expected to be active, this phenomenon can become more significant than the Vasyliunas cycle, and thus dominate circulation within Saturn's magnetosphere. On year-long timescales, this process is estimated to remove upwards of ∼20% of the mass loaded into the magnetosphere by Enceladus.
Laser Desorption/Ionizations Time-of-flight Mass Spectrometry for Future In Situ Planetary Missions
No abstract available
Mass outflow in the nearby proto-planetary system, Beta Pictoris
Previous spectral studies of circumstallar dust around the nearby, candidate proto-planetary system, Beta Pictoris, has detected only infalling gas. The lack of detectable mass outflow has been critical in the interpretation of the origin of the circumstellar gas and in our understanding of the evolutionary status of the Beta Pictoris system. IUE high-dispersion spectra are presented which show, in addition to infall, the presence of mass outflow, with a maximum observed outflow velocity of -60 km/s, and a corresponding instantaneous outflow rate of 1.1 x 10 to the -14th solar mass/yr, or 1.1 x 10 to the -11th Jupiter mass/yr. This mass outflow rate and terminal velocity are comparable to the magnitudes of mass infall rates and terminal velocities observed from late 1986 through early 1988. The implications of these observations on our understanding of the mechanisms producing infall from the surrounding circumstellar disk are discussed, as are the implications for our understanding of the evolutionary status of the Beta Pic system.
Luminosities and masses for three central stars of planetary nebulae in the Magellanic Clouds from ultraviolet spectroscopy with the IUE
Physical parameters of the central stars of the planetary nebulae (PN) P40, N2, and N5 are determined from UV observations by the IUE spacecraft and emission line-data. The observations took place on May 23 and 26, 1981. Derived properties, such as the H-beta, color excess, nebular hydrogen emission, helium emission, and stellar continuum emission, the stellar radius, surface gravity, Zanstra temperature, luminosity, absolute bolometric magnitude, apparent visual magnitude, mass, and Zanstra parameter for the three PN central stars are presented. All the masses were over one solar mass, suggesting a specific PN nuclei mass. The finding was corroborated by all luminosities exceeding the Eddington luminosity for a 0.6 solar mass star, which has previously been calculated for the white dwarf core of a PN.
Dynamical Mass Estimates of the β Pictoris Planetary System through Gaussian Process Stellar Activity Modeling
Nearly 15 yr of radial velocity (RV) monitoring and direct imaging enabled the detection of two giant planets orbiting the young, nearby star β Pictoris. The δ Scuti pulsations of the star, which overwhelm planetary signals, need to be carefully suppressed. In this work, we independently revisit the analysis of the RV data following a different approach than available in the literature to model the activity of the star. We show that a Gaussian process (GP) with a stochastically driven damped harmonic oscillator kernel can model the δ Scuti pulsations. It provides similar results to parametric models but with a simpler framework, using only three hyperparameters. It also enables us to model poorly sampled RV data that were excluded from previous analyses, hence extending the RV baseline by nearly five years. Altogether, the orbit and mass of both planets can be constrained from RV only, which was not possible with the parametric modeling. To characterize the system more accurately, we also perform a joint fit of all available relative astrometry and RV data. Our orbital solutions for β Pic b favor a low eccentricity of 0.029$_{−0.024}^{+0.061}$ and a relatively short period of 21.1$_{−0.8}^{+2.0}$ yr. The orbit of β Pic c is eccentric with 0.206$_{−0.063}^{+0.074}$ with a period of 3.36 ± 0.03 yr. We find model-independent masses of 11.7 ± 1.4 and 8.5 ± 0.5 M Jup for β Pic b and c, respectively, assuming coplanarity. The mass of β Pic b is consistent with the hottest start evolutionary models, at an age of 25 ± 3 Myr. A direct detection of β Pic c would provide a second calibration measurement in a coeval system.
The unique planetary nebula NGC 2818
The planetary nebula NGC 2818, or PK 261 + 8 deg 1, is of special interest due to its apparent association with a Population I open cluster (of the same designation). The results of new observations of the nebula are presented, including interference-filter imagery, photoelectric photometry, and ground-based and IUE spectroscopy. Analysis of its composition based on new IUE and ground-based spectroscopy and model calculations of the very similar planetary nebula NGC 2440 suggests that NGC 2818 is a prototype of the He-rich and N-rich Type I group. Compared to the composition of H II regions in the solar neighborhood, He is 60 percent overabundant, C is 0.3 dex lower, N is 1.0 dex higher, and O, Ne, Si, Cl, and Ar are essentially at comparable values. Analysis of kinematical and morphological data suggests that the nebula is probably associated with the star cluster (revised distance = 3.5 kpc). If so, then it is of exceptional size (radius approximately 1.1 pc), mass (greater than or equal to 0.6 solar mass), expansion velocity (52 + or - 3 km/s), and age (possibly as old as 22,000 yr). Some implications of the results regarding the masses of planetary-nebula progenitors, the nucleosynthesis processes in stars of intermediate mass, and the formation of planetary nebulae are also discussed.
Regolith-Derived Heat Shield for Planetary Body Entry and Descent System with In Situ Fabrication
In this paper we will discuss a new mass-efficient and innovative way of protecting high-mass spacecraft during planetary Entry, Descent & Landing (EDL). Heat shields fabricated in situ can provide a thermal-protection system (TPS) for spacecraft that routinely enter a planetary atmosphere. By fabricating the heat shield with space resources from regolith materials available on moons and asteroids, it is possible to avoid launching the heat-shield mass from Earth. Three regolith processing and manufacturing methods will be discussed: 1) oxygen & metal extraction ISRU processes produce glassy melts enriched in alumina and titania, processed to obtain variable density, high melting point and heat-resistance; 2) compression and sintering of the regolith yield low density materials; 3) in-situ derived high-temperature polymers are created to bind regolith particles together, with a lower energy budget.
Regolith-Derived Heat Shield for Planetary Body Entry and Descent System with In Situ Fabrication
In this paper we will discuss a new mass-efficient and innovative way of protecting high-mass spacecraft during planetary Entry, Descent & Landing (EDL). Heat shields fabricated in situ can provide a thermal-protection system (TPS) for spacecraft that routinely enter a planetary atmosphere. By fabricating the heat shield with space resources from regolith materials available on moons and asteroids, it is possible to avoid launching the heat-shield mass from Earth. Two regolith processing and manufacturing methods will be discussed: 1) Compression and sintering of the regolith to yield low density materials; 2) Formulations of a High-temperature silicone RTV (Room Temperature Vulcanizing) compound are used to bind regolith particles together. The overall positive results of torch flame impingement tests and plasma arc jet testing on the resulting samples will also be discussed.
Detection of life-related compounds on planetary surfaces by gas chromatography-mass spectrometry techniques.
Extraterrestrial life detection program using gas chromatography and mass spectrometry
Compositional Evolution of Saturn's Ring: Ice, Tholin, and 'CHIRON'-Dust
We address compositional evolution in planetary ring systems subsequent to meteoroid bombardment. The huge surface area to mass ratio of planetary rings ensures the importance of this process, given currently expected values of meteoroid flux. We developed a model which includes both direct deposition of extrinsic meteoritic 'pollutants', and ballistic transport of the increasingly polluted ring material as impact ejecta. Certain aspects of the observed regional variations in ring color and albedo can be understood in terms of such a process. We conclude that the regional scale color and albedo differences between the C ring and B ring can be understood if all ring material began with the same composition (primarily water ice, based on other data, but colored by tiny amounts of non-icy, reddish absorber) and then evolved entirely by addition and mixing of extrinsic, neutrally colored, highly absorbing material. This conclusion is readily extended to the Cassini Division and its surroundings as well. Typical silicates are unable to satisfy the ring color, spectroscopic, and microwave absorption constraints either as intrinsic or extrinsic non-icy constituents. However, 'Titan Tholin' provides a satisfactory match for the inferred refractive indices of the 'pre-pollution' nonicy ring material. The extrinsic bombarding material is compatible with the properties of Halley or Chiron, but not with the properties of other 'red' primitive objects such as Pholus. We further demonstrate that the detailed radial profile of color across the abrupt B ring - C ring boundary is quite compatible with such a 'pollution transport' process, and that the shape of the profile can constrain key parameters in the model. We use the model to estimate the 'exposure age' of Saturn's rings to extrinsic meteoroid flux. We obtain a geologically young 'age' which is compatible with timescales estimated independently based on the evolution of ring structure due to ballistic transport, and also with other 'short timescales' estimated on the grounds of gravitational torques.