Can redshift discrepancies in galaxy systems be explained by low-frequency gravitational radiation? I. distant clusters

Some proposals have been made in recent years that extremely low-frequency cosmic gravitational radiation with wavelengths of the order megaparsecs and larger and with the cosmological energy density may be able to explain the virial mass discrepancy in at least some systems of galaxies. The question is rediscussed here with the result that — for all conceivable spectral densities — the gravitational wave influence on the propagation of light from a galaxy cluster does not solve redshift problem for rich and distant clusters — at least if waves with an energy density not exceeding the critical cosmological density are considered.     

Can mass loss and overshooting prevent the excitation of g-modes in blue supergiants?

Thanks to their past history on the main-sequence phase, supergiant massive stars develop a convective shell around the helium core. This intermediate convective zone (ICZ) plays an essential role in governing which g-modes are excited. Indeed, a strong radiative damping occurs in the high-density radiative core but the ICZ acts as a barrier preventing the propagation of some g-modes into the core. These g-modes can thus be excited in supergiant stars by the κ-mechanism in the superficial layers due to the opacity bump of iron, at  log  T = 5.2  . However, massive stars are submitted to various complex phenomena such as rotation, magnetic fields, semiconvection, mass loss, overshooting. Each of these phenomena exerts a significant effect on the evolution and some of them could prevent the onset of the convective zone. We develop a numerical method which allows us to select the reflected, thus the potentially excited, modes only. We study different cases in order to show that mass loss and overshooting, in a large enough amount, reduce the extent of the ICZ and are unfavourable to the excitation of g-modes.     

Macrochondrules in chondrites—Formation by melting of mega‐sized dust aggregates and/or by rapid collisions at high temperatures?

Abstract– Seventy‐four macrochondrules with sizes >3 mm were studied. Considering the extraordinary size of the chondrules (occasionally achieving a mass of 1000 times (and more) the mass of a normal‐sized chondrule), the conditions in the formation process must have been somewhat different compared with the conditions for the formation of the common chondrules. Macrochondrules are typically rich in olivine and texturally similar to specific chondrule types (barred, radial, porphyritic, and cryptocrystalline) of normal‐sized chondrules. However, our studies show that most of the macrochondrules are fine‐grained or have elongated crystals (mostly BO, RP, and C), which lead to the assumption that they were once totally molten and cooled quite rapidly. Porphyritic chondrules belong to the least abundant types of macrochondrules. This distribution of chondrule types is highly unusual and just a reverse of the distribution of chondrule types among the typical‐sized chondrules in most chondrite groups except for the CH and CB chondrites. New chondrule subtypes (like radial‐olivine [RO] or multi‐radial [MR] chondrules) are defined to better describe the textures of certain large chondrules. Macrochondrules may have formed due to melting of huge precursor dust aggregates or due to rapid collisions of superheated melt droplets, which led to the growth of large molten spherules in regions with high dust densities and high electrostatic attraction.     

The reaction of O+2 with atomic nitrogen and NO+· H2O and NO+2 with atomic oxygen

The reactions of atomic nitrogen with O⁺₂ and atomic oxygen and atomic nitrogen with NO⁺· H₂O and NO⁺₂ have been measured at 296 K. The rate constants are reported and the implication of the measurements to atmospheric ion chemistry is discussed.     

Assessing the spatial variability of the ~3 μm OH/H2O absorption feature in CM2 carbonaceous chondrites

H₂O and OH are readily detected in hydrated minerals in CM chondrites via reflectance spectroscopy due to their characteristic vibration absorptions at infrared wavelengths. Previous spectroscopic work on bulk powdered CM chondrites has shown that spectral parameters, like the wavelength position of the “3 μm absorption feature,” vary systematically with the extent to which the samples have been aqueously altered. However, it is yet unclear how these spectral features may vary across an intact meteorite chip when measured at spatial scales smaller than that of the individual components of the meteorite. Here, we explore the spatial variability of this spectral feature and others on intact CM2 chips which, unlike powders, retain their petrologic and textural characteristics. We also model the modal mineralogy of the bulk meteorite powders and correlate this with key spectral features, demonstrating that microscope Fourier transform infrared spectroscopic mapping provides a powerful, rapid, and non-destructive technique for assessing compositional diversity and variations in water–rock interactions in chondritic planetary materials. In all CM2 chondrites studied here, we find that variations in the position, shape, and strength of the 3 μm absorption feature reveal a single chondrite can exhibit as much spectral variation as the entire suite of CM2 chondrites. The observed variations in the position and shape of the 3 μm feature within individual CM2 chondrite chips suggest a range of alteration products (e.g., Mg-rich to Fe-rich phyllosilicates) are present and record sub-mm scale variations in the amount and/or chemistry of the altering fluids. The samples having experienced the most progressive aqueous alteration show the least amount of variability in features like the 3 μm absorption band minimum position, whereas the least altered samples exhibit the most variability. We also find that the bulk spectral signatures in the least altered samples appear to be biased toward the spectral signatures of clasts versus matrix. By extension, asteroid reflectance spectra exhibiting 3 μm absorption features consistent with those measured here may be interpreted in a similar framework in which the spectrum of what may appear to be the least altered asteroids represents an average that belies the true diversity of mineralogy and chemistry of the body.     

H2O on Io? IR spectra of SO2/H2O mixed ices in the 5000-450 cm−1 region

Laboratory transmission IR spectra of relatively thick films (up to 500 m) of mixed H₂O and SO₂ ices were measured at several temperatures between 10 and 130 K in the range 5000-450 cm^–1. In addition to the strong features due to crystalline SO₂ the spectra reveal bands at 3668 cm^–1, 3634 cm^–1 (with some structure) and 3300 cm^–1 which are identified with H₂O in SO₂ environment. Also, there is no overlap between any of the H₂O bands with the 3584 cm^–1 band of SO₂ at any temperature in the above range. The implication of this result is that H₂O, if present on Io, must be far less than 1 part in 10⁵ SO₂.     

Chandra and XMM–Newton Observations of H2O Maser Galaxy Mrk 266

For H₂O megamaser galaxy Mrk 266, its Chandra and XMM–Newton data are analyzed here. It shows existence of two obscured nuclei (separation is ~ 5^″). Our preferred model, the high energy reflected model can fit the hard component of both nuclei spectra well.     

Remarks on the paper “The tidal loss of satellite-orbiting objects and its implications for the lunar surface” by Mark J. Reid

The paper by Reid suggests that masses may be stored in circumlunar orbits for long periods of time, limited only by tidal dissipation. The real loss may, however, be much faster, due to large changes in the orbit caused by the disturbing field of the Earth. It is shown that the example quoted of Jupiter's satellites is inadequate to make the case for stability of such orbits.     

Determining the local abundance of Martian methane and its’ 13C/12C and D/H isotopic ratios for comparison with related gas and soil analysis on the 2011 Mars Science Laboratory (MSL) mission

Understanding the origin of Martian methane will require numerous complementary measurements from both in situ and remote sensing investigations and laboratory work to correlate planetary surface geophysics with atmospheric dynamics and chemistry. Three instruments (Quadrupole Mass Spectrometer (QMS), Gas Chromatograph (GC) and Tunable Laser Spectrometer (TLS)) with sophisticated sample handling and processing capability make up the Sample Analysis at Mars (SAM) analytical chemistry suite on NASA’s 2011 Mars Science Laboratory (MSL) Mission. Leveraging off the SAM sample and gas processing capability that includes methane enrichment, TLS has unprecedented sensitivity for measuring absolute methane (parts-per-trillion), water, and carbon dioxide abundances in both the Martian atmosphere and evolved from heated soil samples. In concert with a wide variety of associated trace gases (e.g. SO₂, H₂S, NH₃, higher hydrocarbons, organics, etc.) and other isotope ratios measured by SAM, TLS will focus on determining the absolute abundances of methane, water and carbon dioxide, and their isotope ratios: ¹³C/¹²C and D/H in methane; ¹³C/¹²C and ¹⁸O/¹⁷O/¹⁶O in carbon dioxide; and ¹⁸O/¹⁷O/¹⁶O and D/H in water. Measurements near the MSL landing site will be correlated with satellite (Mars Express, Mars 2016) and ground-based observations.     

Reflectance of amorphous-cubic NH3 frosts and amorphous-hexagonal H2O frosts at 77K from 1400 to 3000Å

The directional hemispherical reflectance of ammonia and water frosts in the range from 1400 to 3000 Å was measured at 77K. Amorphous and cubic ammonia frosts and amorphous and hexagonal water frosts were studied. The amorphous frosts were grown on a liquid-nitrogen (LN₂)-cooled stainless steel substrate until they were optically thick for 3000 Å radiation. For both gases, deposition at 77K and a pressure of 1.0 × 10^?4 torr resulted in an amorphous frost. The cubic ammonia and the hexagonal water frosts were formed by warming their respective amorphous frosts to 180K. The frosts were then recooled to 77K before radiometric data were recorded. Following frost formation, the reflectance was measured for decreasing wavelengths until it fell below two percent. The amorphous and hexagonal water frosts had continuum reflectances above eighty percent for wavelengths between 2300 and 3000 Å and an absorption cutoff near 1800 Å. The hexagonal water frosts showed an absorption feature with a 100 Å half-width at 1959 Å which had not been previously observed. The amorphous and cubic ammonia frosts also had reflectances above 80% for wavelengths between 2300 and 3000 Å, but their absorption cutoff occurred near 2175 and 2075 Å, respectively. Frost thickness ranged from 2 to 5 mm.     

Collisional Pumping of H $${}_{2}$$ O and СH $${}_{3}$$ OH Masers in C-Type Shock Waves

Astronomy Letters - The collisional pumping of H $${}_{2}$$ O and СH $${}_{3}$$ OH masers in magnetohydrodynamic nondissociative C-type shocks is considered. A grid of C-type shock models...