<Emphasis Type="SmallCaps">profit</Emphasis>: a new alternative for emission-line <Emphasis Type="SmallCaps">pro</Emphasis>file <Emphasis Type="SmallCaps">fit</Emphasis>ting

I briefly describe a simple routine for emission-line profile fitting by Gaussian curves or Gauss–Hermite series. The profit (line-profile fitting) routine represent a new alternative for use in fits data cubes, as the ones from Integral Field Spectroscopy or Fabry–Pérot Interferometry, and may be useful to better study the emission-line flux distributions and gas kinematics in distinct astrophysical objects, such as the central regions of galaxies and star forming regions. The profit routine is written in IDL language and is available at .     

Improvements in the Determination of ISS Ca <Emphasis Type="SmallCaps">ii</Emphasis> K Parameters

Measurements of the ionized Ca ii K line are one of the major resources for long-term studies of solar and stellar activity. They also play a critical role in many studies related to solar irradiance variability, particularly as a ground-based proxy to model the solar ultraviolet flux variation that may influence the Earth’s climate. Full disk images of the Sun in Ca ii K have been available from various observatories for more than 100 years and latter synoptic Sun-as-a-star observations in Ca ii K began in the early 1970s. One of these instruments, the Integrated Sunlight Spectrometer (ISS) has been in operation at Kitt Peak (Arizona) since late 2006. The ISS takes daily observations of solar spectra in nine spectra bands, including the Ca ii K and H lines. We describe recent improvements in data reduction of Ca ii K observations, and present time variations of nine parameters derived from the profile of this spectral line.     

Estimating the Mg <Emphasis Type="SmallCaps">ii</Emphasis> Index from 1961 Through 1981 Using Ca <Emphasis Type="SmallCaps">ii</Emphasis> K Images from the Mt Wilson Observatory

An empirical model of solar UV spectral irradiance has been developed that is based on observed spectral radiance measurements and full disk Ca ii K images. The Mg ii index is then calculated from the estimated spectra in a narrow wavelength range (180 Å) near the Mg ii doublet at 2800 Å. Our long term goal is to expand this wavelength range from 10 to 4000 Å in continuing studies based on spectral data covering this wavelength range (e.g. Skylab, UARS/SUSIM, TIMED/SEE, etc.). Our previous modeling effort produced spectra in this 180 Å range and the resulting Mg ii index values for the period from 1991 through 1995 and we have used observations during this time period to validate the model results. The current paper presents results from this model based on a 21-year portion of the recently digitized Ca ii K images from the Mt Wilson Observatory (MWO) film archive. Here we present details of the model, the required model modifications, and the resulting Mg ii index from 1961 through 1981. Since the NOAA Mg ii index did not begin until 1978, the present model results are compared to a Mg ii index estimated from the F_10.7 radio flux over this 21-year period. The NOAA Mg ii index, which is derived from measured UV spectra, is also included for comparison from late 1978 through 1981.     

Recalibration of the <Emphasis Type="Italic">Soft X-Ray Telescope</Emphasis> Onboard <Emphasis Type="Italic">Yohkoh</Emphasis>

We present a new derivation of the X-ray spectral sensitivity of the Soft X-ray Telescope (SXT) experiment onboard Yohkoh. The recalibration is based upon the hypothesis that, during the first 15 months of the mission, an absorbing material gradually built up on the entrance filters of the telescope. We have also re-evaluated the times and sizes of ruptures of the SXT entrance filters. The impact of this recalibration on derived filter-ratio temperature, emission measure, and calculated spectral irradiance is substantial, especially for SXT data prior to November 1992.     

<Emphasis Type="SmallCaps">pacce</Emphasis>: Perl algorithm to compute continuum and equivalent widths

We present Perl Algorithm to Compute continuum and Equivalent Widths (pacce). We describe the methods used in the computations and the requirements for its usage. We compare the measurements made with pacce and “manual” ones made using iraf splot task. These tests show that for synthetic simple stellar population (SSP) models the equivalent widths strengths are very similar (differences ?0.2 Å) for both measurements. In real stellar spectra, the correlation between both values is still very good, but with differences of up to 0.5 Å. pacce is also able to determine mean continuum and continuum at line center values, which are helpful in stellar population studies. In addition, it is also able to compute the uncertainties in the equivalent widths using photon statistics. The code is made available for the community through the web at http://www.if.ufrgs.br/~riffel/software.html.     

A web of secondary resonances for large <Emphasis Type="Italic">A</Emphasis>/<Emphasis Type="Italic">m</Emphasis> geostationary debris

The dynamics of space debris with very high A/m near the geostationary orbit is dominated by the gravitational coefficient C ₂₂ and the solar radiation pressure. An analysis of the stability of the orbits by the chaos indicator MEGNO and frequency analysis map FAM shows chaotic layers around the separatrix and reveals a web of sub-structures associated to resonances with the annual period of the Sun. This succession of stable thin islands and chaotic layers can be reproduced and explained by a quite simple toy model, based on a pendulum approach, perturbed, through the eccentricity, by the external (Sun) frequency. The use of suitable action-angle variables in the circulation and libration regions of the pendulum allows to point out new resonances between the geostationary libration angle and the Sun’s longitude. They correspond very well (positions, shape, width) to the structures visible on the FAM representations.     

New agegraphic dark energy in <Emphasis Type="Italic">f</Emphasis>(<Emphasis Type="Italic">R</Emphasis>) gravity

In this paper, we study a cosmological application of the new agegraphic dark energy density in the f(R) gravity framework. We employ the new agegraphic model of dark energy to obtain the equation of state for the new agegraphic energy density in a spatially flat universe. Our calculations show, taking n<0, that it is possible to have w _Λ crossing −1. This implies that one can generate a phantom-like equation of state from a new agegraphic dark energy model in a flat universe in the modified gravity cosmology framework. Also, we develop a reconstruction scheme for the modified gravity with f(R) action.     

Plane Symmetric Dark Energy Models in the Form of Wet Dark Fluid in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>,<Emphasis Type="Italic">T</Emphasis>) Gravity

In this paper, we have investigated the plane symmetric space-time with wet dark fluid (WDF), which is a candidate for dark energy, in the framework of f (R,T) gravity Harko et al. 2011, Phys. Rev. D, 84, 024020), where R and T denote the Ricci scalar and the trace of the energy–momentum tensor respectively. We have used the equation of state in the form of WDF for the dark energy component of the Universe. It is modeled on the equation of state p = ω(ρ ? ρ ^?). The exact solutions to the corresponding field equations are obtained for power-law and exponential volumetric expansion. The geometrical and physical parameters for both the models are studied. Also, we have discussed the well-known astrophysical phenomena, namely the look-back time, proper distance, the luminosity distance and angular diameter distance with red shift.     

The Mn <Emphasis Type="SmallCaps">I</Emphasis> 539.47 nm Line Variation in Solar Active Regions

It is a well-established fact that the Mn I 539.47 nm line exhibits significant cycle dependence similar to lines arising in the chromosphere which are affected by non-thermal heating in the chromospheric plages. Among these lines the case of the Mn I 539.47 nm line seems unique. It is of photospheric origin on the basis of theoretical calculations but its cyclic dependence hints at a chromospheric nature. The present work provides further evidence to both connections. The line exhibits asymmetry features and a center-to-limb variation as though influenced by the photospheric granulation. On the other hand an enhancement of the central intensity has been detected in a well identifiable Ca plage area. The line seems to be a promising candidate as an irradiance variation indicator.     

Plane Symmetric Cosmological Model with Quark and Strange Quark Matter in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>, <Emphasis Type="Italic">T</Emphasis>) Theory of Gravity

We studied plane symmetric cosmological model in the presence of quark and strange quark matter with the help of f(R, T) theory. To decipher solutions of plane symmetric space-time, we used power law relation between scale factor and deceleration parameter. We considered the special law of variation of Hubble’s parameter proposed by Berman (Nuovo Cimento B74, 182, 1983) which yields constant deceleration parameter. We also discussed the physical behavior of the solutions by using some physical parameters.     

On the electron density diagnostics of silicon <Emphasis Type="SmallCaps">viii</Emphasis> ion in solar transition region

The conditions for accurate electron density diagnostics in the solar transition region are discussed, and result shows that lines from Si?viii can provide an excellent tool for electron density diagnostics of the emitting plasma. For the Si?viii 1440.50 Å and 1445.75 Å lines, the principle of the electron density diagnostics is discussed for any intensity ratio. By the observed intensity ratio, the diagnostic results of the electron density for the quiet sun and the active region are calculated, and results indicate that in the quiet sun, the averaged electron density is \(\log (N_{e}) = 8.63\); while in the active region, the averaged density gets the maximum \(\log (N_{e}) = 8.86\) in the active region (B), and gets the minimum \(\log (N_{e}) = 8.38\) in the active region (E), where the electron density is in the unit of cm^?3. Finally, the relationship of intensity ratio and electron density is discussed, in the case of lower and higher electron density limits. This discussion is significant in the electron density diagnostics, which will be important for study on coronal heating and acceleration of solar wind.     

On-Orbit Performance of the <Emphasis Type="Italic">Helioseismic and Magnetic Imager</Emphasis> Instrument onboard the <Emphasis Type="Italic">Solar Dynamics Observatory</Emphasis>

The Helioseismic and Magnetic Imager (HMI) instrument is a major component of NASA's Solar Dynamics Observatory (SDO) spacecraft. Since commencement of full regular science operations on 1 May 2010, HMI has operated with remarkable continuity, e.g. during the more than five years of the SDO prime mission that ended 30 September 2015, HMI collected 98.4% of all possible 45-second velocity maps; minimizing gaps in these full-disk Dopplergrams is crucial for helioseismology. HMI velocity, intensity, and magnetic-field measurements are used in numerous investigations, so understanding the quality of the data is important. This article describes the calibration measurements used to track the performance of the HMI instrument, and it details trends in important instrument parameters during the prime mission. Regular calibration sequences provide information used to improve and update the calibration of HMI data. The set-point temperature of the instrument front window and optical bench is adjusted regularly to maintain instrument focus, and changes in the temperature-control scheme have been made to improve stability in the observable quantities. The exposure time has been changed to compensate for a 20% decrease in instrument throughput. Measurements of the performance of the shutter and tuning mechanisms show that they are aging as expected and continue to perform according to specification. Parameters of the tunable optical-filter elements are regularly adjusted to account for drifts in the central wavelength. Frequent measurements of changing CCD-camera characteristics, such as gain and flat field, are used to calibrate the observations. Infrequent expected events such as eclipses, transits, and spacecraft off-points interrupt regular instrument operations and provide the opportunity to perform additional calibration. Onboard instrument anomalies are rare and seem to occur quite uniformly in time. The instrument continues to perform very well.     

<Emphasis Type="Italic">GALEX</Emphasis> and star formation

Wide-field far-UV (FUV, 1344–1786 Å) and near-UV (NUV, 1771–2831 Å) imaging from GALEX provides a deep, comprehensive view of the young stellar populations in hundreds of nearby galaxies, shedding new light on the process of star formation (SF) in different environments, and on the interplay between dust and SF. GALEX’s FUV-NUV color is extremely sensitive to stellar populations of ages up to a few hundred Myrs, unambiguously probing their presence and enabling age-dating and stellar mass estimate, together with the characterization of interstellar dust extinction. The deep sensitivity, combined with the wide field-of-view, made possible in particular the discovery and characterization of star formation in extremely low-density, diffuse gas environments such as outer galaxy disks, tidal tails, low-surface-brightness galaxies (LSB) and dwarf Irregular galaxies, and of rejuvenation episodes in early-type galaxies. Such results provide several missing links for interpreting galaxy classes in an evolutionary context, extend our knowledge of the star-formation process to previously unexplored conditions, constrain models of galaxy disk formation, and clarify the mutual role of dust and star formation. We review a variety of star-forming environments studied by GALEX, and provide some model analysis tools useful for interpretation of GALEX measurements, and potentially as basic science planning tools for next-generation UV instruments.     

Gamma-Spectrometer for the <Emphasis Type="Italic">Phobos-Grunt</Emphasis> mission

The experiment on gamma-ray spectrometry planned to be fulfilled onboard the Phobos-Grunt spacecraft is described. The principles of the experiment and the application of gamma-spectrometry to the space investigations are considered. The design and operation of the instrument are described.     

The expansion field: the value of <Emphasis Type="Italic">H</Emphasis><Subscript>0</Subscript>

Any calibration of the present value of the Hubble constant (H ₀) requires recession velocities and distances of galaxies. While the conversion of observed velocities into true recession velocities has only a small effect on the result, the derivation of unbiased distances which rest on a solid zero point and cover a useful range of about 4–30 Mpc is crucial. A list of 279 such galaxy distances within v < 2,000 km s⁻¹ is given which are derived from the tip of the red-giant branch (TRGB), from Cepheids, and/or from supernovae of type Ia (SNe Ia). Their random errors are not more than 0.15 mag as shown by intercomparison. They trace a linear expansion field within narrow margins, supported also by external evidence, from v = 250 to at least 2,000 km s⁻¹. Additional 62 distant SNe Ia confirm the linearity to at least 20,000 km s⁻¹. The dispersion about the Hubble line is dominated by random peculiar velocities, amounting locally to <100 km s⁻¹ but increasing outwards. Due to the linearity of the expansion field the Hubble constant H ₀ can be found at any distance >4.5 Mpc. RR Lyr star-calibrated TRGB distances of 78 galaxies above this limit give H ₀ = 63.0 ± 1.6 at an effective distance of 6 Mpc. They compensate the effect of peculiar motions by their large number. Support for this result comes from 28 independently calibrated Cepheids that give H ₀ = 63.4 ± 1.7 at 15 Mpc. This agrees also with the large-scale value of H ₀ = 61.2 ± 0.5 from the distant, Cepheid-calibrated SNe Ia. A mean value of H ₀ = 62.3 ± 1.3 is adopted. Because the value depends on two independent zero points of the distance scale its systematic error is estimated to be 6%. Other determinations of H ₀ are discussed. They either conform with the quoted value (e.g. line width data of spirals or the D _n −σ method of E galaxies) or are judged to be inconclusive. Typical errors of H ₀ come from the use of a universal, yet unjustified P–L relation of Cepheids, the neglect of selection bias in magnitude-limited samples, or they are inherent to the adopted models.     

Observations of the Ca <Emphasis Type="SmallCaps">ii</Emphasis> IR Triplet in High Luminosity Quasars: Exploring the Sample

We present a new spectroscopic sample of 11 quasars at intermediate redshift observed with the Infrared Spectrometer and Array Camera (ISAAC) on the ESO Very Large Telescope (VLT), covering O i λ8446 and the Ca ii triplet 8498, 8542, 8662. The new observations – that supplement the sample presented by Martínez-Aldama et al. (2015) – allow us to confirm the constraints on physical conditions and location of the region emitting the low ionization lines, as well as the relation between Ca ii and Fe ii.     

Determining the Absolute Magnitudes of Galactic-Bulge Red Clump Giants in the <Emphasis Type="Italic">Z</Emphasis> and <Emphasis Type="Italic">Y</Emphasis> Filters of the Vista Sky Surveys and the <Emphasis Type="Italic">IRAC</Emphasis> Filters of the Spitzer Sky Surveys

The properties of red clump giants in the central regions of the Galactic bulge are investigated in the photometric Z and Y bands of the infrared VVV (VISTA/ESO) survey and the [3.6], [4.5], [5.8], and [8.0] μm bands of the GLIMPSE (Spitzer/IRAC) Galactic plane survey. The absolute magnitudes for objects of this class have been determined in these bands for the first time: M _Z = ?0.20 ± 0.04, M _Y = ?0.470 ± 0.045, M_[3.6] = ?1.70 ± 0.03, M_[4.5] = ?1.60 ± 0.03, M_[5.8] = ?1.67 ± 0.03, and M_[8.0] = ?1.70 ± 0.03. A comparison of the measured magnitudes with the predictions of theoretical models for the spectra of the objects under study has demonstrated good mutual agreement and has allowed some important constraints to be obtained for the properties of bulge red clump giants. In particular, a comparison with evolutionary tracks has shown that we are dealing predominantly with the high-metallicity subgroup of bulge red clump giants. Their metallicity is slightly higher than has been thought previously, [M/H] ? 0.40 (Z ? 0.038) with an error of [M/H] ? 0.1 dex, while the effective temperature is 4250± 150 K. Stars with an age of 9–10 Gyr are shown to dominate among the red clump giants, although some number of younger objects with an age of ~8 Gyr can also be present. In addition, the distances to several Galactic bulge regions have been measured, as D = 8200–8500 pc, and the extinction law in these directions is shown to differ noticeably from the standard one.     

Global-Mode Analysis of Full-Disk Data from the <Emphasis Type="Italic">Michelson Doppler Imager</Emphasis> and the <Emphasis Type="Italic">Helioseismic and Magnetic Imager</Emphasis>

Building upon our previous work, in which we analyzed smoothed and subsampled velocity data from the Michelson Doppler Imager (MDI), we extend our analysis to unsmoothed, full-resolution MDI data. We also present results from the Helioseismic and Magnetic Imager (HMI), in both full resolution and processed to be a proxy for the low-resolution MDI data. We find that the systematic errors that we saw previously, namely peaks in both the high-latitude rotation rate and the normalized residuals of odd \(a\)-coefficients, are almost entirely absent in the two full-resolution analyses. Furthermore, we find that both systematic errors seem to depend almost entirely on how the input images are apodized, rather than on resolution or smoothing. Using the full-resolution HMI data, we confirm our previous findings regarding the effect of using asymmetric profiles on mode parameters, and also find that they occasionally result in more stable fits. We also confirm our previous findings regarding discrepancies between 360-day and 72-day analyses. We further investigate a six-month period previously seen in \(f\)-mode frequency shifts using the low-resolution datasets, this time accounting for solar-cycle dependence using magnetic-field data. Both HMI and MDI saw prominent six-month signals in the frequency shifts, but we were surprised to discover that the strongest signal at that frequency occurred in the mode coverage for the low-resolution proxy. Finally, a comparison of mode parameters from HMI and MDI shows that the frequencies and \(a\)-coefficients agree closely, encouraging the concatenation of the two datasets.     

Single lunation <Emphasis Type="Italic">N</Emphasis>-observation orbits

Initial orbit determination by least squares of N observations is essentially a linear problem if the coordinates x ₀ and x ₁ at two standard epochs are used as elements. The orbit of a main belt object is approximated within the observational errors by a third degree polynomial during a month. A 4-observation orbit is useful for the initial linking between two nights. Parallax is treated rigorously and future simultaneous space and Earth based observations determine the critical distance directly. The N-observation method is a great simplification of the classical 3-observation orbit followed by a differential correction by N observations.     

Microscope spectrometer for the <Emphasis Type="Italic">Phobos-Grunt</Emphasis> mission

Microscopy and spectroscopy are important methods of studies. The use of a microscope onboard a spacecraft is connected with the fact that the closer approach to the objects and the switch to the in situ measurement methods have become possible. The combination of taking an image and performing a spectral analysis forms a new type of instrument, so-called videospectrometers. The scientific payload of the Phobos-Grunt spacecraft includes the microscope spectrometer designed to analyze the composition of the surface regolith of Phobos in detail.