Observation of the energy spectrum of cosmic diffuse X-rays in the energy range 20 keV-4 MeV

Balloon observations of the cosmic diffuse component of hard X-rays were conducted with two independent directional counters in two energy bands, from 20 keV to 120 keV and from 90 keV to 4 MeV. The build-up effect of primary X-rays and the altitude dependence of atmospheric X-rays were properly taken into account in the analysis of the growth curves. These two experiments gave consistent results in the overlapping energy region. If the differential energy spectrum of the photon flux is represented by a power lawE ^?α, the value of α is 2.3 up to 100 keV, gradually increases to 2.8 at about 500 keV, and decreases to 2.0 thereabove. The spectrum above 300 keV is in parallel to the Apollo-15 spectrum, whereas the absolute intensity is somewhat smaller. The shape of the spectrum suggests the necessity of a multi-component theory on the origin of cosmic diffuse X-rays.     

Spectral analysis of red clump giants and their use as standard candles in the wavebands I and K

Using high resolution and high signal-to-noise ratio observational data, we determined the stellar atmospheric parameters of 19 metal-poor red clump giants and their chemical abundances of the four α elements (i.e., O, Mg, Ca, Si). We discuss the variations, with the iron abundance, of the atmospheric parameters and of the α elements abundances. We examined the absolute stellar magnitudes of 58 red clump giants in the I and K wavebands as well as their relations with the iron abundance, and found that for the analysed range of iron abundance, the correlation with the iron abundance is weaker for the absolute magnitude in the K band than that in the I band, in agreement with theoretical expectations.     

Absolute magnitudes for late‐type dwarf stars for Sloan photometry

We present a new formula for absolute magnitude determination for late‐type dwarf stars as a function of (g – r) and (r – i) for Sloan photometry. The absolute magnitudes estimated by this approach are brighter than those estimated by colour‐magnitude diagrams, and they reduce the luminosity function rather close to the luminosity function of Hipparcos. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A photometric and polarimetric study of the moon's surface

The results of the photometric and polarimetric observation of the Moon's surface with high resolution from October 1969 to March 1971 are discussed. It is found that, for a wide part of the Moon's illuminated surface, the brightnessm, expressed by visual magnitude per square second of arc, can be expressed as $$m = 5.0 - 2.5\log H + 2.5\log \{ {{P_v } \mathord{\left/ {\vphantom {{P_v } P}} \right. \kern-\nulldelimiterspace} P}(\alpha )\} ,$$ whereH is the variable part of Hapke's formula,P _v is the observed polarization degree, andP(α) is a function of the phase angleα. The color shows a tendency to reddening at the enhancement of the lunar brightness, and this is expressed by the relation $$B - V = - 0.2\Delta m + 1.7,$$ where Δm =m + 2.5 logH which is a sort of residual from the brightness calculated by Hapke's formula. Remarkable enhancements of the lunar brightness correspond to solar flares which appeared just before the observations. Because of this the above formula for the observed brightness can be interpreted by assuming the luminescence on the lunar surface stimulated by the solar activity.     

H α Observations of 8 June, 2004 Venus Transit

The cosmic event of Venus transit across the solar disk occurred on 8 June, 2004. The previous such event was witnessed about 122 years ago on 6 December, 1882. We observed this rare transit in H _α 6563 Å line-center from Udaipur Solar Observatory (USO) using both the full-disk and small field-of-view solar telescopes. In the earlier historical transits, a “black-drop” effect was observed in white light images, during the contact phases. The transit of 8 June, 2004 provided a unique opportunity to observe this effect, for the first time, in H _α. We report that the “black-drop” effect is present in H _α also, as in the white light observations made by the ground-based Global Oscillation Network Group (GONG) instrument and the space-borne Transition Region and Coronal Explorer (TRACE) satellite. We did not observe any noticeable “aureole” (atmospheric glow) around Venus during the ingress or egress phases. We have compared the H _α images with the multi-wavelength data obtained from the TRACE satellite.     

From magnitudes and redshifts of supernovae,their light-curves,and angular sizes of galaxies to a tenable cosmology

Early physical cosmologies were based on interpretations of the cosmic redshift for which there was insufficient evidence and on theories of gravitation that appear to be falsified by galactic dynamics. Eventually, the big bang paradigm came to be guarded against refutation by ad hoc hypotheses (dark matter, cosmic inflation, dark energy) and free parameters. Presently available data allow a more satisfactory phenomenological approach. Using data on magnitude and redshift from 892 type Ia supernovae, it is first shown that these suggest that the redshift factor (1+z) is simply an exponential function of distance and that, for “standard candles”, magnitude m=5log[(1+z)ln(1+z)]+const. While these functions are incompatible with a big bang, they characterize certain tired light models as well as exponential expansion models. However, the former are falsified by the stretched light curves of distant supernovae and the latter by the absence of a predicted 1+z increase in the angular sizes of galaxies. Instead, the observations suggest that physical processes speed up and objects contract uniformly as an exponential function of time, standards of measurement not excluded, and only free waves being excepted. Distant events proceed, then, more slowly, while angular sizes remain unaffected, approximately as observed. Since all objects contract in proportion, the Universe retains a static appearance. A corresponding physical theory, which should also explain galactic dynamics, remains yet to be derived from first principles. A way to do this, satisfying also Mach’s principle, is vaguely suggested.     

Statistical method for distance determination of a stellar group

In this paper, we developed statistical method for distance determination of a stellar group. The method depends on the assumption that, the stars scatter around a mean magnitude in a Gaussian distribution. The mean apparent magnitude of the stars is then expressed in terms of the frequency function of the apparent magnitudes, so as to correct for observational incompleteness at the faint end. The problem reduces to the solution of a highly transcendental equation for a given apparent magnitude parameter α. Computational algorithm of the method is illustrated and the numerical solutions of the basic equation are given for some values of α .     

The angular distribution of cosmic rays at the boundary of the heliosphere

Measurements of the sidereal daily variation of the muon intensity at a depth of 60 m.w.e. have been carried out in London using telescopes inclined at 70° to the zenith for the period 1972 to the present. The direction of maximum sensitivity for these telescopes lies in the Earth's equatorial plane and the asymptotic directions of look at the boundary of the heliosphere have been determined by integrating the equation of motion of the primary particles in a model interplanetary magnetic field. In this way the measured sidereal variation can be related to the cosmic ray intensity distribution in interstellar space. It is shown that the observational data are consistent with an axially symmetric intensity distribution of the form ΔI = 0.09 (1 + cosα) % where ΔI is the direction from the mean intensity and α is measured from the direction of maximum intensity which lies at 1^Π = 250° b^Π = ?60°. The most likely interpretation of this result is that the axis of this distribution corresponds to the local direction of the interstellar magnetic field and that the cosmic rays have a bulk streaming motion of 65±15 km s^?1 along the field direction.     

Extrasolar worlds: We should contact aliens?

More than 840 exoplanets have been discovered and many people believe that on some of these planets there may be extraterrestrial civilizations. Astronomers, however, warn against contacts with aliens because of the possible dangers to humankind… In this paper I show that the solar system is a unique phenomenon in the universe and there cannot be any extraterrestrial civilizations. Being the “anthropic center” of the world, the earth and the sun are “designed” for the development of humankind and the cosmos as a supercomputer. This conclusion follows from an analysis of exoplanet orbits that is based on a coherent cosmic oscillation with a period of P ₀ ≈ 9600.6 s (discovered in the sun and some extragalactic sources). The non-Doppler nature of the P ₀ phenomenon is emphasized; this phenomenon appears to be related to the absolute time of the universe in the Newtonian sense.     

MONS OT J004240.69+405142.0: An orphan GRB optical afterglow candidate in Andromeda?

Here we report the serendipitous identification of a bright optical transient in the vicinity of the dwarf elliptical galaxy M 32 (NGC 221). This transient (MONS OT J004240.69+405142.0) was detected using filtered CCD imaging, about 20 arcsec southwest from the core of M 32, at equatorial coordinates α = 00:42:40.69 ± 0.05, δ = +40:51:42.0 ± 0.5, between 04:20:16 and 04:21:46 UT on June 22, 2007. A detailed analysis of the intensity profile of the feature suggests that it is of stellar nature with apparent visual magnitude 9.69 ± 0.15 which gives an absolute magnitude of ?14.7 ± 0.3 if the feature is located in M 31/M 32. Under the assumption of the event reported here being of cosmic origin and although no correlation with GRBs in time or space has been found, the behaviour of the optical transient appears to resemble that of the recently observed GRB 080319B: very fast ascent and decay of several magnitudes within a few minutes. If this interpretation is correct, the afterglow decay was extremely rapid, decreasing by more than 5 mag. in about 2 min, α = 2.4. Given its properties, the event is a possible orphan GRB optical afterglow candidate originated beyond the Local Group. Alternative explanations are also discussed.     

The Nature of the Faint Radio Source Population and Star Formation History derived from Sub-MJY Surveys

We present new results on the nature of the faint radio galaxy population obtained from a deep identification study in the Marano Field. This work represents the highest identification fractions attained to date in literature for sub-mJy radio samples. Star-forming galaxies constitute a significant fraction of the optical counterparts of sub-mJy radio sources, although they are not the dominant identification class (as formerly believed). We also present a new determination of the co-moving star formation density from z=0 to z?0.35 using the radio luminosity function of star-forming galaxies. For the local determination, we used a sample of 231 spiral galaxies taken from the B≤12 Revised Shapley-Ames Catalogue, while for the non-local determination, we used a sample of87 star-forming galaxies taken from the Benn et al. (1993) sample. The inferred local star formation rate is about twice as great as the H_α estimate, while the intermediate 0.05<z<0.35 star formation rate is consistent with coeval ultraviolet and H_α estimates. This is due to large-scale structure, rarely accounted for in estimates of the cosmic star formation history; the situation could improve significantly with deep moderate-area radio surveys.     

The shallow magnitude distribution of asteroid families

It is well known that asteroid families have steeper absolute magnitude (H) distributions for H < 12-13 values than the background population. Beyond this threshold, the shapes of the absolute magnitude distributions in the family/background populations are difficult to determine, primarily because both populations are not yet observationally complete. Using a recently generated catalog containing the proper elements of 106,284 main belt asteroids and an innovative approach, we debiased the absolute magnitude distribution of the major asteroid families relative to the local background populations. Our results indicate that the magnitude distributions of asteroid families are generally not steeper than those of the local background populations for H > 13 (i.e., roughly for diameters smaller than 10 km). In particular, most families have shallower magnitude distributions than the background in the range 15-17 mag. Thus, we conclude that, contrary to previous speculations, the population of kilometer-size asteroids in the main belt is dominated by background bodies rather than by members of the most prominent asteroid families. We believe this result explains why the Spacewatch, Sloan Digital Sky Survey, and Subaru asteroid surveys all derived a shallow magnitude distribution for the dimmer members of the main belt population.We speculate on a few dynamical and collisional scenarios that can explain this shallow distribution. One possibility is that the original magnitude distributions of the families (i.e., at the moment of the formation event) were very shallow for H larger than ∼ 13, and that most families have not yet had the time to collisionally evolve to the equilibrium magnitude distribution that presumably characterizes the background population. A second possibility is that family members smaller than about 10 km, eroded over time by collisional and dynamical processes, have not yet been repopulated by the break-up of larger family members. For this same reason, the older (and possibly characterized by a weaker impact strength) background population shows a shallow distribution in the range 15-60 km.     

Forbush Decreases Associated with Western Solar Sources and Geomagnetic Storms: A Study on Precursors

As suggested in many studies the pre-increases or pre-decreases of the cosmic ray intensity (known as precursors), which usually precede a Forbush decrease, could serve as a useful tool for studying space weather effects. The events in this study were chosen based on two criteria. Firstly, the heliolongitude of the solar flare associated with each cosmic ray intensity decrease was in the 50°?–70°W sector and, secondly, the values of the geomagnetic activity index, Kp _max, were ≥?5. Twenty five events were selected from 1967 to 2006. We have used data on solar flares, solar wind speed, geomagnetic indices (Kp and Dst), and interplanetary magnetic field in our detailed analysis. The asymptotic longitudinal cosmic ray distribution diagrams were plotted using the “Ring of Stations” method for all the events. The results reveal clear signs of precursors in 60 % of selected events.     

Average inhomogeneities in Milky Way SNII and the PAMELA anomaly

A model is presented to estimate the fraction of Supernova Type-II events (SNII) occurring inside vs. outside a spiral arm for a given star formation episode. The probability distribution function (PDF) for this fraction is given for use in models similar to those of Shaviv et al. [13] and [11]. The calculated PDF for the SNII fraction, SNII_in/total, defined as the number of SNII inside a spiral arm divided by the total number of SNII from a star formation event, provides a constraint on the magnitude of supernova remnant (SNR) concentrations used in cosmic ray propagation models attempting to explain the PAMELA anomaly. Despite the concentration of star formation within spiral arms, this model predicts the majority of SNII events actually occur in inter-arm regions and calls into question the SNR concentration assumption of Shaviv et al.     

Measurement of the lunar neutron density profile

Anin situ measurement of the lunar neutron density from 20 to 400 g cm^?2 depth below the lunar surface was made by the Apollo 17 Lunar Neutron Probe Experiment (LNPE) using particle tracks produced by the¹⁰B (n,α)⁷Li reaction. Both the absolute magnitude and the depth profile of the neutron density are in good agreement with theoretical calculations by Lingenfelter, Canfield, and Hampel. However, relatively small deviations between experiment and theory in the effect of Cd absorption on the neutron density and in the relative¹⁴⁹Sm to¹⁵⁷Gd capture rates reported previously (Russet al., 1972) imply that the true lunar¹⁵⁷Gd capture rate is about one half of that calculated theoretically.     

The Herschel-PACS photometer calibration

This paper provides an overview of the PACS photometer flux calibration concept, in particular for the principal observation mode, the scan map. The absolute flux calibration is tied to the photospheric models of five fiducial stellar standards (α Boo, α Cet, α Tau, β And, γ Dra). The data processing steps to arrive at a consistent and homogeneous calibration are outlined. In the current state the relative photometric accuracy is ～2 % in all bands. Starting from the present calibration status, the characterization and correction for instrumental effects affecting the relative calibration accuracy is described and an outlook for the final achievable calibration numbers is given. After including all the correction for the instrumental effects, the relative photometric calibration accuracy (repeatability) will be as good as 0.5 % in the blue and green band and 2 % in the red band. This excellent calibration starts to reveal possible inconsistencies between the models of the K-type and the M-type stellar calibrators. The absolute calibration accuracy is therefore mainly limited by the 5 % uncertainty of the celestial standard models in all three bands. The PACS bolometer response was extremely stable over the entire Herschel mission and a single, time-independent response calibration file is sufficient for the processing and calibration of the science observations. The dedicated measurements of the internal calibration sources were needed only to characterize secondary effects. No aging effects of the bolometer or the filters have been found. Also, we found no signs of filter leaks. The PACS photometric system is very well characterized with a constant energy spectrum νF _ν = λF _λ = const as a reference. Colour corrections for a wide range of sources SEDs are determined and tabulated.     

A study on the Hα line asymmetry of chromospheric flares

The asymmetry of H_α line profiles is an important characteristic in the spectral observations of chromospheric flares, as well as one of the important observational facts of the dynamical process in solar flares. Based on the observed data of the solar spectrograph of Purple Mountain Observatory, some typical asymmetric H_α line profiles are presented. Taking the effects of the nonthermal excitation and ionization of hydrogen atoms into consideration, the asymmetry characteristics of H_α line profiles under different atmospheric models are calculated, and a semi-empirical study on the observed line profiles is thereby made. The results indicate that the downward motion of the chromospheric condensation region can cause the red and blue asymmetries of H_α spectra. We have tried to reproduce the observed asymmetry characteristics in specific flares. It is found that, besides the energy flux of nonthermal particles, the magnitude of spectral index and the height of the velocity field affect the line profile, the flare's atmospheric background model also has some influence on the line profile.     

Low-density structures in the Local Universe. II. Nearby cosmic voids

We present the results of the search for spherical volumes containing no galaxies with luminosities brighter than the Magellanic Clouds in the Local Supercluster and its vicinity. Within a distance of 40 Mpc from us, 89 cosmic voids were discovered with the diameters of 24 to 12 Mpc, containing no galaxies with absolute magnitudes brighter than M _K < ?18.4. A list of these voids and the sky distribution maps are given. It was found that 93% of spherical voids overlap, forming three more extended percolated voids (hypervoids). The largest of them, HV1, has 56 initial spherical cells and extends in a horseshoe shape, enveloping the Local Volume and the Virgo cluster. The Local Void (Tully, 1988) in the Hercules-Aquila region is the closest part of the HV1. Another hypervoid, HV2, contains 22 spherical voids in the Eridanus constellation, and the third compact hypervoid (HV3) comprises 6 spherical cells in the Bootes. The total volume of these voids incorporates about 30% of the Local Universe. Among 2906 dwarf galaxies excluded from the original sample (n = 10502) in the search for spherical volumes, only 68 are located in the voids we have discovered. They are characterized by late morphological types (85% are Ir, Im, BCD, Sm), absolute magnitudes MB ranging from ?13.0 to ?16.7, moderate star formation rates (log SSFR ～ ?10 M _⊙ yr^?1 L _?1 ^⊙ ) and gas reserves per luminosity unit twice to three times larger than in the other dwarf galaxies located in normal environments. The dwarf population of the voids shows a certain tendency to sit shallow near the surfaces of cosmic voids.     

Population II Cepheids in globular clusters

B and V data of Population II Cepheids in M2, M5, M10, M13, M80 and ω Cen are combined in order to obtain period-luminosity and period-colour relations. The mean absolute magnitudes are determined adopting as distance modulus the quantily [V(RR)-M _v(RR)], whereV(RR) is the apparent mean magnitude of RR Lyrae andM _v(RR) is the absolute magnitude derived from the transistion periodP _tr. It is shown that the scatter of the points around the (P-L) and (P-C) relations depends also from the width of the instability strip. In fact the position of the variables in the instability strip may be correlated with their amplitude in the sense that the short period variables (logP<1) which have largest amplitudes are brightest and bluest while the long period variables (logP>1) show a reversed relation. Finally, after correcting the observed colours for the amplitude effect, period-colour-amplitude relations are derived for the both short and long period variables.     

Ineffectiveness of Narrow CMEs for Cosmic Ray Modulation

Monthly coronal mass ejection (CME) counts, – for all CMEs and CMEs with widths >?30^°, – and monthly averaged speeds for the events in these two groups were compared with both the monthly averaged cosmic ray intensity and the monthly sunspot number. The monthly P _i-index, which is a linear combination of monthly CME count rate and average speed, was also compared with the cosmic ray intensity and sunspot number. The main finding is that narrow CMEs, which were numerous during 2007?–?2009, are ineffective for modulation. A cross-correlation analysis, calculating both the Pearson (r) product–moment correlation coefficient and the Spearman (ρ) rank correlation coefficient, has been used. Between all CMEs and cosmic ray intensity we found correlation coefficients r=??0.49 and ρ=??0.46, while between CMEs with widths >?30^° and cosmic ray intensity we found r=??0.75 and ρ=??0.77, which implies a significant increase. Finally, the best expression for the P _i-index for the examined period was analyzed. The highly anticorrelated behavior among this CME index, the cosmic ray intensity (r=??0.84 and ρ=??0.83), and the sunspot number (r=+?0.82 and ρ=+?0.89) suggests that the first one is a very useful solar–heliospheric parameter for heliospheric and space weather models in general.