Interpretation of the 6818.9-Å methane feature observed on Jupiter,Saturn, and Uranus

High-resolution (0.1-Å) spectra of the 6818.9-Å methane feature obtained for Jupiter, Saturn, and Uranus by K. H. Baines, W. V. Schempp, and W. H. Smith ((1983). Icarus56, 534–542) are modeled using a doubling and adding code after J. H. Hansen ((1969). Astrophys. J.155, 565–573). The feature's rotational quantum number is estimated using the relatively homogeneous atmosphere of Saturn, with only J = 0 and J = 1 fitting the observational constraints. The aerosol content within Saturn's northern temperate region is shown to be substantially less than at the equator, indicating a haze only half as optically thick. Models of Jupiter's atmosphere are consistent with the rotational quantum-number assignment. Synthetic line profiles of the 6818.9-Å feature observed on Uranus reveal that a substantial haze exists at or above the methane condensation region with an optical depth eight times greater than previously reported. Seasonal effects are indicated. The methane column abundance is 5 ± 1 km-am. The mixing ratio of methane to hydrogen within the deep unsaturated region of the planet is 0.045 ± 0.025, based on an H₂ column abundance of 240 ± 60 km-am (W. H. Smith, W. Macy, and C. B. Pilcher (1980). Icarus43, 153–160), thus indicating that the methane comprises between one-sixth and one-half of the planet's mass. However, proper reevaluation of H₂ quadrupole features accounting for the haze reported here may significantly reduce the relative methane abundance.     

High-Resolution 0.33-0.92 μm Spectra of Iapetus, Hyperion, Phoebe, Rhea, Dione, and D-Type Asteroids: How Are They Related?

New high-resolution spectra in the 0.33 to 0.92 μm range of Iapetus, Hyperion, Phoebe, Dione, Rhea, and three D-type asteroids were obtained on the Palomar 200-inch telescope and the double spectrograph. The spectra of Hyperion and the low-albedo hemisphere of Iapetus can both be closely matched by a simple model that is the linear admixture of the spectrum of a medium-sized, high-albedo icy saturnian satellite and D-type material. Our results support an exogenous origin to the dark material on Iapetus; furthermore, this material may share a common origin and a similar means of transport with material on the surface of Hyperion. The recently discovered retrograde satellites of Saturn (Gladman et al., Nature412, 163-166) may be the source of this material. The leading sides of Callisto and the Uranian satellites may be subjected to a similar alteration mechanism as that of Iapetus: accretion of low-albedo dust originating from outer retrograde satellites. Phoebe does not appear to be related to either Iapetus or Hyperion. Separate spectra of the two hemispheres of Phoebe show no identifiable global compositional differences.     

Are PSR 0656+14, PSR 0950+08, and PSR 1822-09 gamma-ray pulsars?

The possible discovery of three new -ray pulsars PSR 0656+14, PSR 0950+08, and PSR 1822-09 (Ma, Lu, Yu, and Young, 1993) in data obtained with the COS-B experiment is reinvestigated using a refined technique for pulsar light curve analysis. The results of this study do not confirm the previously claimed -ray pulsar nature of any of these pulsars. Even when using the standard epoch folding technique in conjunction with energy-dependent acceptance cones, we do not detect pulsed -ray emission from these sources. We suspect that insufficient position accuracy is the cause for the discrepancy between our results and those of Maet al. (1993). We do not rule out that any one of the three candidates, or all of them, is in fact a -ray pulsar, but their spin properties must differ from those derived by Maet al. (1993). More work is needed to determine the correct high-energy properties of these three sources.     

Models, figures, and gravitational moments of Jupiter’s satellites Io and Europa

Two types of trial three-layer models have been constructed for the satellites Io and Europa. In the models of the first type (Io1 and E1), the cores are assumed to consist of eutectic Fe-FeS melt with the densities ρ ₁ = 5.15 g cm^?3 (Io1) and 5.2 g cm^?3 (E1). In the models of the second type (Io3 and E3), the cores consist of FeS with an admixture of nickel and have the density ρ ₁ = 4.6 g cm^?3. The approach used here differs from that used previously both in chosen model chemical composition of these satellites and in boundary conditions imposed on the models. The most important question to be answered by modeling the internal structure of the Galilean satellites is that of the condensate composition at the formation epoch of Jupiter’s system. Jupiter’s core and the Galilean satellites were formed from the condensate. Ganymede and Callisto were formed fairly far from Jupiter in zones with temperatures below the water condensation temperature, water was entirely incorporated into their bodies, and their modeling showed the mass ratio of the icy (I) component to the rock (R) component in them to be I/R ～ 1. The R composition must be clarified by modeling Io and Europa. The models of the second type (Io3 and E3), in which the satellite cores consist of FeS, yield 25.2 (Io3) and 22.8 (E3) for the core masses (in weight %). In discussing the R composition, we note that, theoretically, the material of which the FeS+Ni core can consist in the R accounts for ～25.4% of the satellite mass. In this case, such an important parameter as the mantle silicate iron saturation is Fe# = 0.265. The Io3 and E3 models agree well with this theoretical prediction. The models of the first and second types differ markedly in core radius; thus, in principle, the R composition in the formation zone of Jupiter’s system can be clarified by geophysical studies. Another problem studied here is that of the error made in modeling Io and Europa using the Radau-Darvin formula when passing from the Love number k ₂ to the nondimensional polar moment of inertia $\bar C$ . For Io, the Radau-Darvin formula underestimates the true value of $\bar C$ by one and a half units in the third decimal digit. For Europa, this effect is approximately a factor of 3 smaller, which roughly corresponds to a ratio of the small parameters for the satellites under consideration α _Io/α _Europa ～ 3.4. In modeling the internal structure of the satellites, the core radius depends strongly on both the mean moment of inertia I* and k ₂. Therefore, the above discrepancy in $\bar C$ for Io is appreciable.     

High-resolution 3-μm spectra of Jupiter: Latitudinal spectral variations influenced by molecules, clouds, and haze

We present latitudinally-resolved high-resolution (R = 37,000) pole-to-pole spectra of Jupiter in various narrow longitudinal ranges, in spectral intervals covering roughly half of the spectral range 2.86-3.53 μm. We have analyzed the data with the aid of synthetic spectra generated from a model jovian atmosphere that included lines of CH₄, CH₃D, NH₃, C₂H₂, C₂H₆, PH₃, and HCN, as well as clouds and haze. Numerous spectral features of many of these molecular species are present and are individually identified for the first time, as are many lines of and a few unidentified spectral features. In both polar regions the 2.86-3.10-μm continuum is more than 10 times weaker than in spectra at lower latitudes, implying that in this wavelength range the single-scattering albedos of polar haze particles are very low. In contrast, the 3.24-3.53 μm the weak polar and equatorial continua are of comparable intensity. We derive vertical distributions of NH₃, C₂H₂ and C₂H₆, and find that the mixing ratios of NH₃ and C₂H₆ show little variation between equatorial and polar regions. However, the mixing ratios of C₂H₂ in the northern and southern polar regions are ∼6 and ∼3 times, respectively, less than those in the equatorial regions. The derived mixing ratio curves of C₂H₂ and C₂H₆ extend up to the 10⁻⁶ bar level, a significantly higher altitude than most previous results in the literature. Further ground-based observations covering other longitudes are needed to test if these mixing ratios are representative values for the equatorial and polar regions.     

“Beautiful and cantankerous instruments”: telescopes, technology, and astronomy’s changing practice

Between the dedication of the 200” Hale Telescope in 1948 and the completion of today’s 8–10 m behemoths, astronomers’ most iconic symbol, the telescope itself—its design, its technology, and its use—was transformed as a research tool. The importance of this is deceptively simple: in astronomy, technological innovations have often led to new discoveries. Driven by the need to get as much observing time as possible and the desire to take advantage of the best observing conditions, modern observatories have experimented with new technologies and modes of collecting images and spectra. This entailed a re-casting of the telescope by astronomers and science managers as a factory of scientific data. At the same time, contemporary astronomers express considerable unease and apprehension about how these technological changes have altered, in ways subtle and profound, the nature of astronomical observing and what it meant to be an astronomer. This short essay addresses the issues associated with these recent changes in astronomical practice and their connections to astronomers’ desire for ever larger and more complex telescopes.     

OSO-8 observations of CaII H and K,MgII h and k,Lα and Lβ above a sunspot

Observations with the French (L.P.S.P.) experiment on board OSO-8 of a sunspot and nearby plage region are described. The behaviour of the emission cores of the Ca II H and K and Mg II h and k resonance lines is very similar and the correspondence in intensity between the four lines persists in all observed features. In contrast, the Lyman lines show little correlation with the other lines. Their emission regions appear broader in the spectroheliograms than the underlying sunspot structure and must not necessarily possess a counterpart in lower layers. From the central intensity of L above the umbra an electron density of 4.3 × 10¹⁰ cm^-3 n _e ^* 2.3 × 10¹¹ cm^-3 at 20 000 K is estimated.Mitteilungen aus dem Kiepenheuer-Institut Nr. 186.Stockholm Observatorium, S-13300 Saltsjöbaden, Sweden.Laboratoire de Physique Stellaire et Planétaire, CNRS, P.O. Box 10, F-91370 Verrières-le-Buisson, France.     

Photometry and spectroscopy of Ⅱ Peg,IM Peg and UX Ari

V band photometry of three RS CVn stars, II Peg, IM Peg and UX Ari, is carried out to study the physical properties of these variables. We verified the significant and regular optical photometric variability to be present in all three stars. The strong photometric variability and emission of Hα and Ca II H K using high resolution optical spectroscopy with the Hanle Echelle Spectrograph(HESP),which operates in conjunction with the Himalayan Chandra Telescope, verify the strong chromospheric activity which is present in RS CVn stars. The photometric studies of II Peg, UX Ari and IM Peg were subjected to light curve analysis for spot parameters using a two-starspot model.     

Is conventional paradigm in extragalactic astronomy seriously incomplete? - Iwanowska's chains,their dynamics and redshifts

The perspective given by Iwanowska (inFrom Stars to Quasars, Toru, 1989, volume devoted to Prof. Iwanowska) is developed. The redshifts of the Iwanowska's lines galaxies form five states. We used all the redshifts indicated in the Iwanowska's concept. Our hypotheses can be easily verified in the future checking the new redshifts of galaxies belonging to five lines of galaxies selected by Iwanowska. This solution of the problem of stability of the lines is in serious disagreement with the concept of an anthropic universe advocated by Barrow, Tipler, and Wheeler, nevertheless it fits the view of Grabiska on the problem of antropicity, observation, evaluation of extragalactic data and meta-astronomy, cf. T. GrabiskaRealism and Instrumentalism in Contemporary Physics, Wroclaw Technological Institute, 1992, M. Zabierowski,Status of the Observer in Contemporary Physics, Institute of Physics, 1990.     

Secular brightness increases of Titan,Uranus, and Neptune, 1972–1976

The brightnesses of Titan, Uranus, and Neptune in b (4718 ÅA) and y (5508 ÅA) have increased linearly since 1972 at rates ranging from 0.005 to 0.025 mag yr^?1. The observations were made differentially on a number of nights each season with respect to a network of comparison stars whose relative magnitudes were determined by independent measurements. Solar phase coefficients were derived for each object, and all observations have been normalized to zero solar phase angle and mean heliocentric distances. No explanation for the changes has been found, but a possible influence of solar activity upon planetary albedo is suggested by the fact that all of the objects observed have brightened during the declining half of the solar cycle.     

The interstellar band at λ 4430 Å and the abundance of interstellar iron,titanium, and molecular hydrogen

For the direction to a number of stars the depletion of interstellar gaseous iron and titanium as well as the relative abundance of molecular hydrogen and the strength of the interstellar band at 4430 Å were determined by different authors and can be found in the literature. In this paper it is shown that the difference (A _c-A_co) is a more reliable measurement of the column density of 4430 Å absorbers than the usually used central depth,A _c, because the positive valueA _co ofA _c forE(B-V)=0, i.e. the intercept with theA _c axis of a least-squares fit to the observedA _c vsE(B-V) data, is with a high probability not caused by an interstellar effect.There was no correlation found between the interstellar depletion of iron and titanium, respectively, and (A _c-A_co), whereas a tendency exists that with increasing relative molecular hydrogen abundance the number of 4430 Å absorbers per hydrogen atom decreases. If the carriers of the 4430 Å absorbers are interstellar grains, then these grains must be altered during the same process in which molecular hydrogen is built. The found correlation is also compatible with the assumption that the 4430 Å absorber is related to an interstellar gaseous species.     

New Hα Stars, HHL Objects, and a Cometary Nebula

Preliminary results of observations of a region containing known H stars are presented. The observations were made on the 2.6-m telescope of the V. A. Ambartsumian Byurakan Astrophysical Observatory in August 2000. A VAGR integral field spectrograph was used in the observations. The size of the region studied is about 6×11 arcmin. Besides the two already known, five new H stars and five HHL objects were discovered in this region. One of these stars coincides with the well-known object RNO 127. One infrared and one cometary nebula were discovered. The presence of so many peculiar objects in a region of such size suggests that it is one of the youngest star-forming regions.     

MeV Properties of the γ-ray Blazars PKS1622-297, 3C454.3 and CTA102

1　IntroductionTheblazarsPKS 1 62 2 2 97,3C 454 .3andCTA 1 0 2werefirstlydetectedasγ raysourcesby　　Fig .1　TheCOMPTELspectraoftheflareandquiescentstate (top)aswellasthecombinedCOMPTEL/EGRETspectrumoftheflarestateforPKS 1 62 2 -2 97(bottom) .EGRET/CGRO [1 ,2 ,3 ] .WehaveconsistentlyanalyzedtheCOMPTELdata (0 .75-3 0MeV)onthese 3blazars.Inouranalysesweselected 2 8CGROviewingperiods (VPs)forPKS 1 62 2 2 97between’91and’97,and 2 2VPsfor 3C 454 .3andCTA 1 0 2between…     

Instruments of RT-2 experiment onboard CORONAS�CPHOTON and their test and evaluation V: onboard software, data structure, telemetry and telecommand

The onboard software and data communication in the RT-2 Experiment onboard the Coronas?CPhoton satellite is organized in a hierarchical way to effectively handle and communicate asynchronous data generated by the X-ray detectors. A flexible data handling system is organized in the X-ray detector packages themselves and the processing electronic device, namely RT-2/E, has the necessary intelligence to communicate with the three scientific payloads by issuing commands and receiving data. It has direct interfacing with the Satellite systems and issues commands to the detectors and processes the detector data before sending to the satellite systems. The onboard software is configured with several novel features like (a) device independent communication scheme, (b) loss-less data compression and (c) Digital Signal Processor. Functionality of the onboard software along with the data structure, command structure, complex processing scheme etc. are discussed in this paper.     

Results of observation of Cyg γ-2, BL Lac, 3C66A, Mk 501, and the Crab nebula by the GT-48 gamma-ray telescope in 2006

The active galactic nuclei BL Lac, 3C66A, and Mk501, as well as the Crab nebula and the Cyg γ-2 source were observed in 2006 at the Crimean Astrophysical Observatory using the GT-48 gamma-ray telescope. Very high energy (VHE) gamma-ray fluxes at a high confidence level (Q > 4) were detected from the active galactic nuclei and the Crab nebula. VHE gamma-ray fluxes from the unidentified gamma-ray source Cyg γ-2 and the X-ray source Cyg X-3 were recorded during observations of Cyg γ-2.     

CO Clouds around SNR G21.8-0.6 and G32.8-0.1

We made the first CO(I—0) mapping to SNR G21.8-0.6 and SNR G32.8-0.1, both associated with OH 1720 MHz maser.Based on the morphological correspondence and velocity and position agreement between the radio remnant and the CO clouds,we tentatively identify the clouds that are respectively interacting with the two SNRs.     

Preface: Workshop on matter,astrophysics, gravitation,ions and cosmology—MAGIC23

We outline our experience in organizing the first edition of the Workshop on Matter, Astrophysics, Gravitation, Ions and Cosmology, held in virtual and in-person format, denominated MAGIC23, held from 6 to 10 March, 2023, in Praia do Rosa, Santa Catarina, Brazil. The event aimed to bring together leading academic scientists, professors, students, and research scholars for exchanging experiences and discuss the most recent innovations, trends, practical challenges, and experimental and theoretical solutions adopted in the investigation fields within the scope of the meeting. The workshop offered to the participants a platform for scientific and academic projects, partnerships, and presentation of high-quality research contributions describing original and unpublished results on topics related to matter, astrophysics, gravitation, ions, and cosmology.     

IUE detector saturation and the new 2800 Å absorption featre ‘discovered’ by Karim,Hoyle, and Wickramasinghe

The broad 2800 Å absorption feature discovered by Karim, Hoyle, and Wickramasingle is instrumental in origin. The feature is produced by IUE detector saturation effects in overexposed spectra.     

Galileo’s telescope: history, scientific analysis, and replicated observations

In the summer of 1609, Galileo Galilei started to improve upon the Dutch spyglass. Only a few months were needed to increase the magnifying power of the instrument up to 30 times. This transformation allowed Galileo to perform astronomical observations destined to change the traditional Universe. At present, the Institute and Museum of History of Science of Florence is conducting a research programme on the lenses of early telescopes. Historical research is combined with scientific analyses conducted by the National Institute of Applied Optics in Arcetri, the National Institute of Nuclear Physics in Florence, and the Glass Experimental Station in Murano. The shape and composition of the lenses are studied by applying different techniques. Moreover, the composition of early lenses and scientific glass objects are compared. Finally, Galileo’s observations are checked with an optical replica of Galileo’s telescope held at the Astrophysical Observatory in Arcetri.     

Пульсар в краБе: замагниченные трещины в коре как ключ к механизмам истечения вещества, радио- и высокочастотного излучений

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