The abundance of ammonia in the atmosphere of Jupiter

A laboratory curve of growth analysis was made on the lines in two ammonia bands located at 6450 Å and 10800 Å and the abundance of ammonia in the atmosphere of Jupiter was determined. Lines in the 6450 Å band appear to fall on the weak line section of the curve of growth, while those in the 10800 Å band fall in the transition region. The abundance values obtained from these bands are 13.0±3 m atm and 15±8 m atm, respectively.Measurements of the intensity distribution in the 6450 Å band in the laboratory and in the Jovian spectra show that the intensity of several lines in this band is highly dependent on the temperature. Strengths for some of the lines in the 6450 Å band were determined and half-widths of some strong lines were also measured. The effective pressure found from these half-width values is 2.5 atmospheres.Contributions from the University of Illinois, Chicago Circle Physics Department, No. 12.     

The UV continuum 1450–2100 Å and the problem of the solar temperature minimum

This study is based on a set of ten solar rocket spectra well exposed for photometry photographed on July 27, 1966 by Purcell, Snider, and Tousey.The photometry of the far UV continuum illustrates the transition of the solar temperature minimum at 1700 Å in the solar spectrum - (a) the continuum intensity decreases by 30–50% between 1700 Å and the¹ D limit of silicon at 1682 Å, and (b) the equivalent brightness temperature shows minimum values throughout the spectral range 1540–1682 Å, which average just under 4700 ± 100K.The minimum UV brightness temperature is 300K higher than the far infrared measurement of the solar minimum temperature, and possible reasons for this are discussed.Brightness temperatures measured in prominent CO band heads and in the aluminum 1937 Å auto-ionization line also are given.     

Observation of the absolute intensity and the centre-to-limb variation of the sun in the vacuum ultraviolet region

The absolute intensities and the centre-to-limb variations of the Sun at three wavelengths of 1629 Å, 1684 Å, and 1739 Å were measured by a rocket-borne spectrometer flown from the Kagoshima Space Centre on 1 September 1971. The spectrometer was a double-dispersive trichrometer, whose spectral and spatial resolutions were 8.3 Å and 1.3 respectively. The results concerning the absolute intensities were similar to those measured by the Harvard College Observatory group. The results for the centre-to-limb variation at 1629 Å and 1684 Å seem to support the HSRA model but not those at 1739 Å.     

Evidence of N2-ice on the surface of the icy dwarf Planet 136472 (2005 FY9)

We present high signal precision optical reflectance spectra of 2005 FY9 taken with the Red Channel Spectrograph and the 6.5-m MMT telescope on 2006 March 4 UT (5000-9500 Å; 6.33 Å pixel⁻¹) and 2007 February 12 UT (6600-8500 Å; 1.93 Å pixel⁻¹). From cross-correlation experiments between the 2006 March 4 spectrum and a pure CH₄-ice Hapke model, we find the CH₄-ice bands in the MMT spectrum are blueshifted by 3 ± 4 Å relative to bands in the pure CH₄-ice Hapke spectrum. The higher resolution MMT spectrum of 2007 February 12 UT enabled us to measure shifts of individual CH₄-ice bands. We find the 7296, 7862, and 7993 Å CH₄-ice bands are blueshifted by 4 ± 2, 4 ± 4, and 6 ± 5 Å. From four measurements we report here and one of our previously published measurements, we find the CH₄-ice bands are shifted by 4 ± 1 Å. This small shift is important because it suggest the presence of another ice component on the surface of 2005 FY9. Laboratory experiments show that CH₄-ice bands in spectra of CH₄ mixed with other ices are blueshifted relative to bands in spectra of pure CH₄-ice. A likely candidate for the other component is N₂-ice because its weak 2.15 μm band and blueshifted CH₄ bands are seen in spectra of Triton and Pluto. Assuming the shift is due to the presence of N₂, spectra taken on two consecutive nights show no difference in CH₄/N₂. In addition, we find no measurable difference in CH₄/N₂ at different depths into the surface of 2005 FY9.     

X-ray and extreme ultraviolet (1–400 Å) spectroscopy of the sun,from OSO-III

X-ray spectra of the sun have been obtained during solar flares. New emission lines are observed in the spectral range from 1.3 Å to 3 Å, and 8 Å–20 Å, the most intense of the new emission features being tentatively attributed to optical transitions in high stages of ionization of iron (Fexxv through Fexx). Studies of the variability of these lines during flares provide new information of the development of a hot plasma in the initial stages of the flare event.     

Spectroscopy from laser-produced plasmas at flare temperatures

A discussion of laboratory spectra similar in temperatures and ion abundances to solar flare spectra is given. The laboratory spectra were obtained from high temperature plasmas produced by high power lasers and low inductance vacuum sparks. The current state of knowledge regarding line identifications in laboratory spectra is reviewed, and some of the results are used to identify lines in the high temperature solar flare spectrum in the 100 Å region and in the 1000 Å region. In addition, the physical dimensions and temperatures of the hot regions in the plasmas produced by the low inductance spark were recently measured, and a short summary of the results is given.A review paper given at the IAU Colloquium No. 27 on Ultraviolet and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas, held at Harvard University, 9–11 September, 1974.On leave from Tel-Aviv University, Tel-Aviv, Israel.     

Limb-darkening observations between 1800 and 2900 Å

We succeeded in several attempts at measuring the solar limb-darkening in the continuous spectrum between 1800 Å and 2900 Å. Good spectroheliograms were obtained during a rocket flight in November 1964 and during a balloon flight in October 1966 at 2190 Å, 2665 Å, 2885 Å, and 1980 Å, 2235 Å respectively. A rocket flown at the beginning of 1967 provided excellent spectra allowing the measurement of center-to-limb variation in the continuum and lines from 1800 Å to 2800 Å.The first series of pictures yielded absolute values of the central intensity leading to a minimum temperature close to 4700 °K. The continuous opacity of the photosphere layers has been deduced from the two first experiments. It seems that a non-metallic source of continuous absorption must be taken into account between 2500 Å and 3000 Å. Moreover, as the source functions for the shortest wavelengths show a very flat variation near the minimum temperature, it seems that the transition zone between the photosphere and the chromosphere must be very gradual.These results are discussed in the light of the latest results deduced from the new spectra obtained.     

Grain size dependence of far-infrared extinction spectra of amorphous fine grains

The far-infrared extinction spectra of fused silica grains with the size range from 1.8 m to 60 Å were measured. The spectra depend clearly on the grain size. For large grain sizes (from 1.8 m to 400 Å) the spectra show almost the ^–2 dependence ( is the wavelength), which resembles that of the bulk material. For fine grains (70 and 60 Å) the spectra are less steep, the wavelength dependence being ^–1. This grain size dependence of extinction spectra agrees essentially with the prediction of Seki and Yamamoto.     

Analysis of the high resolution Mg xi X-ray spectra

In this paper, the second in a series dealing with high-resolution spectra (9.14–9.33 Å) measured on board the INTERCOSMOS-16 satellite, the analysis of the physical conditions in the coronal part of the McMath 14352 active region is performed. The temperature structure of the emitting plasma is investigated on the basis of the photon fluxes measured in six selected wavelength bands involving the resonance, intercombination, and forbidden lines of the Mg xi ion and a number of satellite lines. Relative line intensities are discussed in terms of the active region plasma density.     

EURD: The Mission and the Stellar Absolute Fluxes of B-Type Stars

We present here stellar spectra of B stars obtained with the EURD spectrograph, one of the three instruments on board MINISAT-01. EURD is a spectrograph specially designed to detect diffuse radiation in thewavelength range between 350 and 1100 Å with 5 Å spectral resolution. EURD main scientific targets are: the spectrum of interstellar medium,atmospheric airglow, decaying neutrinos, Moon and early type stars.     

The absorption spectrum of atmospheric water vapor in the vicinity of the He 10830 Å triplet

Wavelengths of clean atmospheric water lines, and some solar lines, in the wavelength interval 10750 Å to 10900 Å have been measured to an accuracy approaching ± 1 mÅ. Strengths and wavelengths have been measured for all atmospheric water lines with absorption coefficients > 5 × 10^–4 cm^–1 gm^–1 cm^–2 at 280K, that lie within 15 Å of the He I 10830 Å featur of the stronger He component is affected by a weak water line which reduces atmospheric transmission by nearly 1 % with 10 mm precipitable water in the line of sight.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.     

Extreme ultraviolet spectrum of the solar flare of 2114 UT March 27, 1967

Scanning spectrometer measurements in the range 1310–270 Å, observed from the satellite OSO 3, are reported for the solar flare of 2114 UT March 27, 1967. This flare was a long lasting sequence of bursts with EUV spectra consisting of enhanced lines and recombination continua normally emitted from the chromosphere and chromosphere-corona transition region, with unusually small increases in lines normally emited from the corona. An EUV flare spectrum is presented and suggested as one example for interpreting broadband observations of EUV bursts. Any broadband continuum other than known recombination continua contributed less than 6 % of the meassured line and hydrogen recombination continua in the range 270–1310 Å. The ratio of photon flux of Ciii 1176 Å to that of Ciii 977 Å was 0.86, which suggests an ambient density in the region of emission greater than 10¹² cm^-3 at temperatures near 60000 K.     

Spatially Resolved Far Ultraviolet Spectroscopy of the Jovian Aurora

Spatially resolved spectra in four 50-Å FUV spectral windows were obtained across the jovian aurora with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. Nearly simultaneous ultraviolet imaging makes it possible to correlate the intensity variations along the STIS slit with those observed in the images and to characterize the global auroral context prevailing at the time of the observations. Spectra at ∼1-Å resolution taken in pairs included an unabsorbed window and a spectral region affected by hydrocarbon absorption. Both sets of spectra correspond to an aurora with a main oval brightness of about 130 kilorayleighs of H₂ emission. The far ultraviolet color ratios I(1550-1620 Å)/I(1230-1300 Å) are 2.3 and 5.9 for the noon and morning sectors of the main oval, respectively. We use an interactive model coupling the energy degradation of incoming energetic electrons, auroral temperature and composition, and synthetic H₂ spectra to fit the intensity distribution of the H₂ lines. It is found that the model best fitting globally the spectra has a soft energy component in addition to a 10 erg cm⁻² s⁻¹ flux of 80 keV electrons. It provides an effective H₂ temperature of 540 K. The relative intensity of temperature-sensitive H₂ lines indicates differences between the auroral main oval and polar cap emissions. The amount of methane absorption across the polar region is shown to vary in a way consistent with temperature. For the second spectral pair, the polar cap shows a higher attenuation by CH₄, indicating a harder precipitation along high-latitude magnetic field lines.     

Shoemaker-Levy 9 impact with Jupiter: Spectral peculiarities of the impact sites H,K, L,N, and D + G + S + R group

Long-slit CCD spectra of the impact parallel of Jupiter were obtained on July 20–21, 1994. Observations were made at Nasmith focus of the 2.6 m Shajn telescope of the Crimean Astrophysical Observatory. Observed spectra covered 4600–10,250 Å at a resolution of 4.5 Å.Combined investigations of the Nasmith spectra, both the spatial profiles for different spectral regions and extracted spectra for different sites of the crash latitude, show that the impact spots have some spectral peculiarities. Detectable absorption in the observed wavelength region is the general peculiarity of the observed impact sites, except for CH₄ bands at 8900 Å and 1 m, where methane absorption was weakened. Also, our analysis evidenced that there are two types of the spectral peculiarities. One of them, related to the great spots D + G + R + S, K, and L, shows that the absorption in the impact sites is increasing gradually to the blue with respect to the unaffected sites. The other, related to the medium-sized spots, H and N, shows no obvious changes in the gradient of the spots' spectra over a wide wavelength region, except that for the green region, where absorption is slightly weakened.     

Solar X-ray spectra observed from the ‘Intercosmos-4’ satellite and the ‘Vertical-2’ rocket

Results are given of the detailed analysis of fourteen Fe xxv-xxiii lines ( = 1.850–1.870 Å) in the spectra of a solar flare on 16 Nov. 1970. The spectra were obtained with a resolution of about 4 × 10^–4 Å, which revealed lines not previously observed and allowed the measurement of line profiles. The measured values of the wavelengths and emission fluxes are presented and compared with theoretical calculations. The analysis of the contour of the Fe xxv line ( = 1.850 Å) leads to the conclusion that there is unidirectional macroscopic gas motion in the flare region with the velocity (projection on the line of sight) ± 90 km s^–1.Measurements of the 8.42 Å Mg xii and 9.16 Å Mg xi lines in the absence of solar flares indicate prolonged existence of active regions on the solar disk with T _e = 4–6 × 10⁶K and emission measure ME 10⁴⁸ cm^–3. The profile of the Mg xii line indicates a macroscopic ion motion with a velocity up to 100 km s^–1.     

Observations of the infrared FeXIII lines in the solar corona of 12 November, 1966

The purpose of this paper is to report on some intensity measurements of the Fe xiii lines at 10 747 Å and 10 798 Å made during the total eclipse of 12 November, 1966. Infrared spectra were taken of the solar corona at a dispersion of 90 Å per mm, using an RCA image converter and spectrograph aboard the NASA CV 990 aircraft off the coast of southern Brazil. The spectra have been reduced to equivalent width in terms of the coronal continuum and values derived for different points in the corona.The observed equivalent widths of the lines lie in the range 10 to 30 Å for the 10 747 line and 5 to 12 Å for the 10 798 line. The ratio of these equivalent widths is found to vary from 2.3 in the inner corona to 6 at a point 1.36 solar radii from the center of the Sun.The above results are discussed in terms of the excitation mechanisms involved in producing the lines. In particular, the results are compared with the recent theoretical calculations of Chevalier and Lambert, who are the first to include the effects of proton collisions in the excitation of the 3p ^{2 3} P levels of Fexiii. Our observations are consistent with an electron density of 4 × 10⁸ in the inner corona; a value which compares favorably with those derived by other observers from the strength of the K continuum. These are, to our knowledge, the first eclipse observations of the infrared Fe xiii lines which indicate that proton collisions are important in the excitation of the coronal lines. The coronal abundance of iron is estimated from the equivalent width of the 10 747 line, and in common with other observers we find an overabundance as compared to the photospheric abundance by a factor of 10.     

Atomic oxygen in the comae of comets

We report on the detection of atomic oxygen lines in the spectra of 8 comets. These forbidden lines are a result of the photodissociation of the parent oxygen-bearing species directly into an excited state. We used high resolution spectra obtained at the McDonald Observatory 2.7 m telescope to resolve the cometary oxygen lines from the telluric oxygen lines and from other cometary emissions. We find that the relative intensities of the two red lines (6300.304 and 6363.776 Å) are consistent with theory. The green line (5577.339 Å) has an intensity which is about 10% of the sum of the intensities of the two red lines. We show that collisional quenching may be important in the inner coma. If we assume the relative excitation rates of potential parents which have appeared in the literature, then H₂O would be the parent of the cometary green oxygen line. However, those rates have been questioned. We measured the width of the three oxygen lines and find that the green line is wider than either of the two red lines. The finding of a wider line could imply a different parent for the green and red lines. However, the constancy of the green to red line flux ratio suggests the parent is the same for these lines but that the exciting photons have different energies.     

Photospheric and chromospheric oscillations in the base of coronal holes

In this paper we carry out an analysis of the spatial–temporal line-of-sight velocity variations measured in the chromospheric (H, H) and photospheric (Fei 6569 Å, Fei 4864 Å, Nii 4857 Å) lines at the base of 17 coronal holes. Time series of a duration from 43 to 120 min were recorded with the CCD line-array and the CCD matrix. Rather frequently we observed quasi-stationary upward flows with a measured velocity of up to 1 km s^–1 in the photosphere and up to 4–5 km s^–1 in the chromosphere (equivalent radial velocity of up to 3 km s^–1 and up to 12–15 km s^–1 accordingly) near dark points on the chromospheric network boundary inside polar CH. Line-of-sight velocity fluctuation spectra contain meaningful maxima in the low-frequency region clustering around the values 0.4, 0.75, and 1 mHz. Usually, the spatial localization of these maxima mutually coincides and, in our opinion, coincides with the chromospheric network boundary. Acoustic 3- and 5-min oscillations are enhanced in the coronal hole region and reach 1 km s^–1 in the photosphere and 3–4 km s^–1 in the chromosphere. These oscillations are not localized spatially and are distinguished throughout the entire region observed.     

Ultra-violet nightglow spectrum from 1900 Å to 3400 Å

Two spectra of the ultra-violet nightglow from 1900 Å to 3400 Å have been recorded by a fast wide-field spectrograph during balloon flights from Aire sur Adour, France on 15 September, 1969 and on 5 October, 1970. These two spectra are composed of theOi line at 2972 Å, of the molecular oxygen Herzberg band systemA ³ _u ⁺ X ³ _g ^– and of a molecular band system that seems to belong to the NO SystemX ² C ² X ⁺, situated at 1991 ű4 Å, 2060 ű4 Å and 2136 ű4 Å. Around 2540 Å, there is absorption by ozone at the altitudes at which the spectra were recorded (35 km and 40 km). We present our calculated value of ozone absorption at 35 km, and the zenith-horizon variation of the nightglow emission.