Observations of the gamma-ray flux from the X-ray source Cyg X-3 in 1994–1995

We present the observations of Cygnus X-3 carried out with the GT-48 gamma-ray telescope at the Crimean Astrophysical Observatory in 1994–1995. The mean gamma-ray flux at energy E>10¹² eV is shown to be approximately equal to 1.3×10^?11 cm^?2 s^?1. The flux in 1994 was much lower than that in 1995, being (6.2±2.6)×10^?12 cm^?2 s^?1; i.e., it was statistically insignificant. The flux in 1995 was (2.7±0.7)×10^?11 cm^?2 s^?1. Thus, the very high energy gamma-ray emission from Cyg X-3 is variable. These measurement results can be used to obtain upper limits on the flux from Cyg X-3 in 1994–1995.     

Devasthal Fast Optical Telescope Observations of Wolf–Rayet Dwarf Galaxy Mrk 996

The Devasthal Fast Optical Telescope (DFOT) is a 1.3 meter aperture optical telescope, recently installed at Devasthal, Nainital. We present here the first results using an Hα filter with this telescope on a Wolf–Rayet dwarf galaxy Mrk 996. The instrumental response and the Hα sensitivity obtained with the telescope are (3.3 ± 0.3) × 10^???15 erg s^?1 cm^?2/counts s^?1 and 7.5 × 10^???17 erg s^?1 cm^?2 arcsec^?2 respectively. The Hα flux and the equivalent width for Mrk 996 are estimated as (132 ± 37) × 10^?14 erg s^?1 cm^?2 and ～96 Å respectively. The star formation rate is estimated as 0.4 ± 0.1M _⊙ yr^?1. Mrk 996 deviates from the radio-FIR correlation known for normal star forming galaxies with a deficiency in its radio continuum. The ionized gas as traced by Hα emission is found in a disk shape which is misaligned with respect to the old stellar disk. This misalignment is indicative of a recent tidal interaction in the galaxy. We believe that galaxy–galaxy tidal interaction is the main cause of the WR phase in Mrk 996.     

Activity of the 1998 Leonid shower from video records

Abstract— Video observations of the Leonid shower aboard two aircraft in the 1998 Leonid multi-instrument aircraft campaign and from ground locations in China are presented. Observing at altitude proved particularly effective, with four times higher rates due to low extinction and low angular velocity at the horizon. The rates, derived from a total of 2500 Leonid meteors, trace at least two distinct dust components. One dominated the night of 1998 November 16/17. This two-day wide component was rich in bright meteors with r = N (m + 1)/N (m) ≈ 1.5 (s = 1.4) and peaked at an influx of 3.1 ± 0.4 × 10^?12 m^?2 s^?1 (for particles of mass <7 × 10^?5 g) at solar longitude Λ₀ ≈ 234.52 (Eq. J2000). The other more narrow component peaked on 1998 November 17/18 at Λ₀ = 235.31 ± 0.01. Rates were elevated above the broad component between Λ₀ = 235.15 and 235.40, symmetric around the current node of the parent comet 55P/Tempel-Tuttle, peaking at 5.1 ± 0.2 × 10^?12 m^?2 s^?1. The population index was higher, r = 1.8 ± 0.1 (s = 1.7), but not as high as in past Leonid storms (r = 3.0). The flux profile of this component has an unusual asymmetric shape, which implies a blend of contributions from at least two different but relatively recent epochs of ejection. The variation of r across the profile might be due to mass-dependent ejection velocities of the narrowest component. High rates of faint meteors occurred only in an isolated five-minute interval at Λ₀ = 235.198, which is likely the result of a single meteoroid breakup in space.     

4U 0115+63 from RXTE and INTEGRAL data: Pulse profile and cyclotron line energy

We analyze the observations of the transient X-ray pulsar 4U 0115+63 with the RXTE and INTEGRAL observatories in a wide X-ray (3–100 keV) energy band during its intense outbursts in 1999 and 2004. The energy of the fundamental harmonic of the cyclotron resonance absorption line near the maximum of the X-ray flux from the source (luminosity range 5 × 10³⁷–2 × 10³⁸ erg s^?1) is ～11 keV. When the pulsar luminosity falls below ～5 × 10³⁷ erg s^?1, the energy of the fundamental harmonic is displaced sharply toward the high energies, up to ～16 keV. Under the assumption of a dipole magnetic field configuration, this change in cyclotron harmonic energy corresponds to a decrease in the height of the emitting region by ～2 km, while other spectral parameters, in particular, the cutoff energy, remain essentially constant. At a luminosity ～7 × 10³⁷ erg s^?1, four almost equidistant cyclotron line harmonics are recorded in the spectrum. This suggests that either the region where the emission originates is compact or the emergent spectrum from different (in height) segments of the accretion column is uniform. We have found significant pulse profile variations with energy, luminosity, and time. In particular, we show that the profile variations from pulse to pulse are not reduced to a simple modulation of the accretion rate specified by external conditions.     

Infrared photometry of Nova Delphini 2013 (=V339 Del) in the first sixty days after its outburst

The results of JHKLM photometry for Nova Delphini 2013 obtained in the first sixty days after its outburst are analyzed. Analysis of the energy distribution in a wide spectral range (0.36–5 µm) has shown that the source mimics the emission of normal supergiants of spectral types B5 and A0 for two dates near its optical brightness maximum, August 15.94 UT and August 16.86 UT, respectively. The distance to the nova has been estimated to be D ≈ 3 kpc. For these dates, the following parameters have been estimated: the source’s bolometric fluxes ～9 × 10^?7 and ～7.2 × 10^?7 erg s^?1 cm^?2, luminosities L ≈ 2.5 × 10⁵ L _⊙ and ≈2 × 10⁵ L _⊙, and radii R ≈ 6.3 × 10¹² and ≈1.2 × 10¹³ cm. The nova’s expansion velocity near its optical brightness maximum was ～700 km s^?1. An infrared (IR) excess associated with the formation of a dust shell is shown to have appeared in the energy distribution one month after the optical brightness maximum. The parameters of the dust component have been estimated for two dates of observations, JD2456557.28 (September 21, 2013) and JD2456577.18 (October 11, 2013). For these dates, the dust shell parameters have been estimated: the color temperatures ≈1500 and ≈1200 K, radii ≈6.5 × 10¹³ and 1.7 × 10¹⁴ cm, luminosities ～4 × 10³ L _⊙ and ～1.1 × 10⁴ L _⊙, and the dust mass ～1.6 × 10²⁴ and ～10²⁵ g. The total mass of the material ejected in twenty days (gas + dust) could reach ～1.1 × 10^?6 M _⊙. The rate of dust supply to the nova shell was ～8 × 10^?8 M _⊙ yr^?1. The expansion velocity of the dust shell was about 600 km s^?1.     

γ-ray observations from the OSO-3 satellite

The result on λ-rays obtained from the analysis of 5800 orbits of data from the University of Rochester telescope on board the OSO-3 satellite are presented. For γ-rays of energy greater than 100 MeV, an upper limit of 2.3×10^?4 cm^?2 s^?1 std has been placed on the diffuse (assumed isotropic) flux. An upper limit to the flux from the Sun is set at 3.2×10^?5 and 2.4×10^?5 cm^?2 s^?1 for energies greater than 50 MeV and 100 MeV, respectively. All flux values are calculated assuming a π⁰-decay source of γ-rays.     

Cosmic ray acceleration in hypernova remnants expanding in wind bubbles of Wolf-Rayet progenitor stars

The determination of the origin of cosmic rays with observed energies in excess of 10¹⁷ eV that exceed the expected energies of cosmic rays accelerated by supernova remnants in the galaxy is a pressing problem in modern astrophysics. Hypernova remnants are one of the possible galactic sources of cosmic rays with energies of up to 10¹⁹ eV. Hypernovae constitute a class of extremely powerful supernova explosions, whose supposed progenitors are massive Wolf-Rayet stars. We analyze the special aspects of acceleration of cosmic rays in hypernova remnants that expand in wind bubbles of Wolf-Rayet progenitor stars. We show that these cosmic rays may attain maximum energies of 10¹⁸ eV even with a relatively conservative choice of acceleration parameters and account for tens of percent of the total cosmic ray flux observed in the vicinity of the earth in the energy range of 10¹⁶–10¹⁸ eV if the galactic hypernova explosion rate in the modern epoch reaches ? _S ～ 10^?4 year^?1.     

X-rays from supernovae remants 3C 400.2 (≡ G53.7-2.2) and MSH 15-56

Detection of two new soft X-ray sources and their identification with the supernova remnants (RNRs) 3C400.2 and MSH 15-56, is reported. From the observed X-ray flux in the 0.7–2.0 keV energy range, the X-ray luminosity of 3C400.2 is derived to be in the range of (2.7–5.3)×10³⁵ ergs s^?1 and that of MSH 15-56 in the range of (0.9–1.6)×10³⁵ ergs s^?1. If we use the standard adiabatic shockwave model for the SNR's, an age of ～(1.4–3.2)×10⁴ yr is derived for 3C400.2 whereas MSH 15-56 is found to be younger of an age of (5–10)×10³ yr.     

Lightnings and nitric oxide on Venus

In an updating of energy characteristics of lightnings on Venus obtained from Venera-9 and -10 optical observations, the flash energy is given as 8 × 10⁸ J and the mean energy release of lightnings is 1 erg cm^?2 s which is 25 times as high as that on the Earth. Lightnings were observed in the cloud layer. The stroke rate in the near-surface atmosphere is less than 5 s^?1 over the entire planet if the light energy of the stroke exceeds 4 × 10⁵ J and less than 15 s^?1 for (1–4) × 10⁵ J.The average NO production due to lightnings equals 5 × 10⁸ cm^?2 s^?1, the atomic nitrogen production is equal to 7 × 10⁹ cm^?2s^?1,the N flux toward the nightside is 3.2 × 10⁹ cm^?2s^?1, the number densities [N] = 3 × 10⁷cm^?3 and [NO] = 1.8 × 10⁶cm^?3 at 135 km. Almost all NO molecules in the upper atmosphere vanish interacting with N and the resulting NO flux at 90-80 km equals 5 × 10⁵cm^?2s^?1, which is negligibly small as compared with lightning production. If the predissociation at 80–90 km is regarded as the single sink of NO, its mixing ratio, f_NO, is 4 × 10^?8, for the case of a surface sink f_NO = 0.8 × 10^?9 at 50 km. Excess amounts, $\text{f}{}_{\mathrm{<mtext>NO</mtext>}}\text{? 4 × 10}{}^{\mathrm{?8}}$, may exist in the thunderstorm region.     

Spectral properties of hydromagnetic fluctuations near 4 and 5 a.u.

Power spectra of vector components of interplanetary magnetic field fluctuations near 4–5 a.u. during quiet intervals show a frequency dependence very close to f^s over the frequency range 4 × 10^?5 to 9 × 10^?3 Hz (corresponding to periods of 7 h-2 min). While the spectra are generally very close to power law in frequency, variations in slope among the spectra exceed those expected from random errors and may represent true temporal variations. Mean slopes corrected for systematic error are s = ? 1.50±0.02 (Pioneer 10, mean heliocentric distance 5.3 a.u.) and s = ? 1.52±0.02 (Pioneer 11, mean heliocentric distance 3.9 a.u.) and are consistent with several determinations of spectral slope for magnetic fluctuations near 1 a.u. Radial evolution of the perturbations is investigated by choosing data samples in which Pioneer 10 and 11 and the sun are nearly colinear. The dependence on heliocentric distance of σ_c², the composite vector variance, and of σ_c/B_mag, where B_mag is the mean magnitude of the magnetic field, show that the radial variation of fluctuation amplitude is highly variable in time with a dependence on heliocentric distance typically in the range R^?1 to R^?1.5. These observations are compared with theoretical models of outward propagating Alfven waves of solar origin and of MHD turbulence. The mean slopes agree well with that expected for turbulence. The significant variability observed in spectral slopes and in the radial dependence of fluctuation amplitude in data selected specifically for conditions of relative magnetic quiet is noteworthy and urges caution in modeling heliospheric magnetic microstructure in studies of galactic cosmic ray modulation.     

Radial plasma drifts deduced from VLF whistler mode signals: A modelling study

VLF whistler mode signals have previously been used to infer radial plasma drifts in the equatorial plane of the plasmasphere and the field-aligned ionosphere-protonosphere coupling fluxes. Physical models of the plasmasphere consisting of O⁺ and H⁺ ions along dipole magnetic field lines, and including radial Ez × B drifts, are applied to a mid-latitude flux tube appropriate to whistler mode signals received at Wellington, New Zealand, from the fixed frequency VLF transmitter NLK (18.6 kHz) in Seattle, U.S.A. These models are first shown to provide a good representation of the recorded Doppler shift and group delay data. They are then used to simulate the process of deducing the drifts and fluxes from the recorded data. Provided the initial whistler mode duct latitude and the ionospheric contributions are known, the drifts at the equatorial plane can be estimated to about ± 20 ms^?1 (～10–15%), and the two hemisphere ionosphere-protonosphere coupling fluxes to about ± 10¹² m^?2 s^?1 (～40%).     

Testing the Distance Scale of the Gaia TGAS Catalogue by the Kinematic Method

We have studied the simultaneous and separate solutions of the basic kinematic equations obtained using the stellar velocities calculated on the basis of data from the Gaia TGAS and RAVE5 catalogues. By comparing the values of Ω'₀ found by separately analyzing only the line-of-sight velocities of stars and only their proper motions, we have determined the distance scale correction factor p to be close to unity, 0.97 ± 0.04. Based on the proper motions of stars from the Gaia TGAS catalogue with relative trigonometric parallax errors less than 10% (they are at a mean distance of 226 pc), we have found the components of the group velocity vector for the sample stars relative to the Sun (U, V,W)_⊙ = (9.28, 20.35, 7.36) ± (0.05, 0.07, 0.05) km s^?1, the angular velocity of Galactic rotation Ω⁰ = 27.24 ± 0.30 km s?1 kpc?1, and its first derivative Ω'₀ = ?3.77 ± 0.06 km s^?1 kpc^?2; here, the circular rotation velocity of the Sun around the Galactic center is V₀ = 218 ± 6 km s^?1 kpc (for the adopted distance R₀ = 8.0 ± 0.2 kpc), while the Oort constants are A = 15.07 ± 0.25 km s^?1 kpc^?1 and B = ?12.17 ± 0.39 km s^?1 kpc^?1, p = 0.98 ± 0.08. The kinematics of Gaia TGAS stars with parallax errors more than 10% has been studied by invoking the distances from a paper by Astraatmadja and Bailer-Jones that were corrected for the Lutz–Kelker bias. We show that the second derivative of the angular velocity of Galactic rotation Ω'₀ = 0.864 ± 0.021 km s^?1 kpc^?3 is well determined from stars at a mean distance of 537 pc. On the whole, we have found that the distances of stars from the Gaia TGAS catalogue calculated using their trigonometric parallaxes do not require any additional correction factor.     

Cosmic GRB 060428C detected in the field of view of the IBIS and SPI telescopes onboard the INTEGRAL observatory and its early afterglow

While analyzing the archival data of the INTEGRAL observatory, we detected and localized a cosmic gamma-ray burst recorded on April 28, 2006, by the IBIS/ISGRI and SPI telescopes in their fields of view. Since the burst was not revealed by the INTEGRAL burst alert system (IBAS), information about its coordinates was not distributed in time and no search for its afterglow was conducted. The burst was recorded by the KONUS/WIND and RHES SI satellites. Its 20–200-keV fluence was 2.3 × 10^?6 erg cm^?2, the peak flux was 3.6 × 10^?7 erg cm^?2 s^?1 (3.9 phot. cm^?2 s^?1). The burst had a complex multipeaked profile and stood out among typical bursts by an increase in its hardness with time. At the flux peak, the spectrum was characterized by a photon index α ? ?1.5 and a peak energy E _p ? 95 keV. The burst lasted for ～12 s, after which its afterglow decaying as a power law with an index γ ～ ?4.5 was observed at energies 15–45 keV. The spectral hardness decreased noticeably during the afterglow.     

The solar modulation of electrons in the heliosphere

The propagation and modulation of electrons in the heliosphere play an important part in improving our understanding and assessment of the modulation processes. A full three-dimensional numerical model is used to study the modulation of galactic electrons, from Earth into the inner heliosheath, over an energy range from 10 MeV to 30 GeV. The modeling is compared with observations of 6–14 MeV electrons from Voyager 1 and observations at Earth from the PAMELA mission. Computed spectra are shown at different spatial positions. Based on comparison with Voyager 1 observations, a new local interstellar electron spectrum is calculated. We find that it consists of two power-laws: In terms of kinetic energy E, the results give E ^?1.5 below ～500 MeV and E ^?3.15 at higher energies. Radial intensity profiles are computed also for 12 MeV electrons, including a Jovian source, and compared to the 6–14 MeV observations from Voyager 1. Since the Jovian and galactic electrons can be separated in the model, we calculate the intensity of galactic electrons below 100 MeV at Earth. The highest possible differential flux of galactic electrons at Earth with E=12 MeV is found to have a value of 2.5×10^?1 electrons m^?2?s^?1?sr^?1?MeV^?1 which is significantly lower (a factor of 3) than the Jovian electron flux at Earth. The model can also reproduce the extraordinary increase of electrons by a factor of 60 at 12 MeV in the inner heliosheath. A lower limit for the local interstellar spectrum at 12 MeV is estimated to have a value of (90±10) electrons m^?2?s^?1?sr^?1?MeV^?1.     

Soft X-ray sources at the centers of the elliptical galaxies NGC 4472 and NGC 4649

Analysis of recent observations of the elliptical galaxies NGC 4472 and NGC 4649 with the Chandra X-ray space telescope has revealed faint soft X-ray sources at their centers. The sources are located at the galactic centers, to within 1″, and are most likely associated with the radiation from the supermassive black holes that are assumed to be at the optical centers of these galaxies. Interest in these and several other similar objects stems from the unusually low luminosity of the supermassive black hole embedded in a dense interstellar medium. The sources have soft energy spectra in the Chandra energy range 0.2–10 keV. The source is detected at a 3σ confidence level only in the range 0.2–0.6 keV with a luminosity of ～6×10³⁷ erg s^?1 in NGC 4649 and in the range 0.2–2.5 keV with a luminosity of ～ 1.7×10³⁸ erg ^?1 in NGC 4472.     

Ultraviolet Spectral Behavior of TVCol During and After Flaring Activity

We studied the intermediate polar TVCol during and after its flare in November 1982 observed in the ultraviolet range with the International Ultraviolet Explorer. Two spectra revealing the variations of emission lines at different times are presented. We have estimated a new value of the reddening from the 2200 Å absorption feature, E (B ? V ) = 0.12 ± 0.02, and calculated the line fluxes of C IV and He II emission lines produced in the outer accretion disk. The average ultraviolet luminosity of emitting region during and after the flare is approximately 4 × 10³² erg s^?1 and 9 × 10³⁰ erg s^?1, the corresponding average mass accretion rate is nearly 3 × 10¹⁵ erg s^?1 (4.76 × 10^?11M_⊙ yr^?1) and 5 × 10¹³ erg s^?1 (7.9³ × 10^?13M_⊙ yr^?1), and the average temperature of the emitting region during and after flare is estimated to be of about 3.5 × 10³ K and 2 × 10³ K. We attribute this flare to a sudden increase in the mass accretion rate leading to the outburst activity.     

Diagnostics of the early explosion phase of a classical nova using its X-ray emission: A model for the X-ray outburst of CI Camelopardalis in 1998

We have computed a spherically symmetric model for the interaction of matter ejected during the outburst of a classical nova with the stellar wind from its optical component. This model is used to describe the intense X-ray outburst (the peak 3–20 keV flux was ～2 Crab) of the binary system CI Camelopardalis in 1998. According to our model, the stellar wind from the optical component heated by a strong shock wave produced when matter is ejected from the white dwarf as the result of a thermonuclear explosion on its surface is the emission source in the standard X-ray band. Comparison of the calculated and observed time dependences of the mean radiation temperature and luminosity of the binary system during its outburst has yielded very important characteristics of the explosion. We have been able to measure the velocity of the ejected matter immediately after the onset of the explosion for the first time: it follows from our model that the ejected matter had a velocity of ～2700 km s^?1 even on 0.1–0.5 day after the outburst onset and it flew with such a velocity for the first 1–1.5 day under an external force, possibly, the radiation pressure from the white dwarf. Subsequently, the matter probably became transparent and began to decelerate. The time dependence of the mean radiation temperature at late expansion phases has allowed us to estimate the mass of the ejected matter, ～10^?7–10^?6 M _⊙. The mass loss rate in the stellar wind required to explain the observed peak luminosity of the binary system during its outburst has been estimated to be \(\dot M\) ～ (1 ? 2) × 10^?6 M _⊙ yr^?1.     

26Al‐26Mg systematics of Ca‐Al‐rich inclusions,amoeboid olivine aggregates,and chondrules from the ungrouped carbonaceous chondrite Acfer 094

Abstract— We report in situ magnesium isotope measurements of 7 porphyritic magnesium‐rich (type I) chondrules, 1 aluminum‐rich chondrule, and 16 refractory inclusions (14 Ca‐Al‐rich inclusions [CAIs] and 2 amoeboid olivine aggregates [AOAs]) from the ungrouped carbonaceous chondrite Acfer 094 using a Cameca IMS 6f ion microprobe. Both AOAs and 9 CAIs show radiogenic ²⁶Mg excesses corresponding to initial ²⁶Al/²⁷Al ratios between ～5 × 10^?5 ～7 × 10^?5 suggesting that formation of the Acfer 094 CAIs may have lasted for ～300,000 years. Four CAIs show no evidence for radiogenic ²⁶Mg; three of these inclusions (a corundum‐rich, a grossite‐rich, and a pyroxene‐hibonite spherule CAI) are very refractory objects and show deficits in ²⁶Mg, suggesting that they probably never contained ²⁶Al. The fourth object without evidence for radiogenic ²⁶Mg is an anorthite‐rich, igneous (type C) CAI that could have experienced late‐stage melting that reset its Al‐Mg systematics. Significant excesses in ²⁶Mg were observed in two chondrules. The inferred ²⁶Al/²⁷Al ratios in these two chondrules are (10.3 ± 7.4) × 10^?6 (6.0 ± 3.8) × 10^?6 (errors are 2σ), suggesting formation 1.6^+1.2_‐0.6 and 2.2^+0.4_‐0.3 Myr after CAIs with the canonical ²⁶Al/²⁷Al ratio of 5 × 10^?5. These age differences are consistent with the inferred age differences between CAIs and chondrules in primitive ordinary (LL3.0–LL3.1) and carbonaceous (CO3.0) chondrites.     

Night-time radial plasma drifts and coupling fluxes at L = 2.3 from whistler mode measurements

A method recently reported for measuring radial drifts in the equatorial plane and ionosphere-magnetosphere coupling fluxes from the Doppler shifts and group delays on whistler mode signals is applied to VLF transmissions from station NLK on 18.6 kHz. Data from 22 nights, primarily during the months November to February, are analysed. When averaged over a time of about 90 min, drifts found are accurate to ±20 ms^?1, corresponding to an equatorial electric field accuracy of ±0.05 mVm^?1 and fluxes, to ±1.5 × 10¹² el m^?2 s^?1 (two hemisphere total). Given currently accepted values of coupling fluxes, the flux accuracy is of marginal value on individual nights, but useful information on average behaviour may be obtained.We find fluxes generally contribute less than 20% to the measured Doppler shift, most of which is therefore produced by cross-L drifts. To an accuracy of about 20% then, Doppler data alone may give information on these drifts. Doppler shift data previously accumulated over a number of years and relating to signals in ducts near L = 2.3 are re-examined. Dominating the nightly behaviour is an inward drift which reaches a maximum of ～ 100 ms^?1 as the duct ends cross the dusk terminator and an outward drift at dawn of the same magnitude which is initiated when the duct end crosses the terminator in the E or lower F-region. In some months, separate effects can be seen corresponding to sunrise at each end of the duct.During the night, there are clear differences between December and June solstice drift behaviour which are as yet unexplained.Two-hemisphere-total coupling fluxes found from the 22 nights of data are ～ 1?2 × 10¹² elm^?2s^?1. At the time of the evening maximum of inward drift the flow is to the ionosphere, but later in the night upfluxes were measured.