Highlights from the first year of Odin observations

Hjalmarson, Å.; Frisk, U.; Olberg, M.; Bergman, P.; Bernath, Peter F.; Biver, Nicolás; Black, J. H.; Booth, R. S.; Buat, V.; Crovisier, J.; Curry, Charles L.; Dahlgren, Magnus; Encrenaz, P.; Falgarone, É.; Feldman, P. A.; Fich, M.; Florén, Hans-Gustav; Fredrixon, Mathias; Gérin, M.; Gregersen, E. M.; Hagström, Magnus; Harju, J.; Hasegawa, T.; Horellou, C.; Johansson, Lars; Kyrölä, E.; Kwok, Sun; Larsson, Bengt; Lecacheux, A.; Liljeström, T.; Lindqvist, Michael; Liseau, R.; Llewellyn, E. J.; Mattila, K.; Mégie, G.; Mitchell, G. F.; Murtagh, Donal; Nyman, L.-Å.; Nordh, H. L.; Olofsson, A. O. H.; Olofsson, G.; Olofsson, H.; Pagani, L.; Persson, G.; Plume, R.; Rickman, H.; Ristorcelli, I.; Rydbeck, G.; Sandqvist, Aa.; Schéele, F. von; Serra, G.; Torchinsky, S.; Tothill, N.; Volk, Kevin; Wiklind, T.; Wilson, C. D.; Winnberg, A.; Witt, G.

doi:10.1051/0004-6361:20030337

Cited by 33 publications

(11 citation statements)

References 32 publications

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“…The Odin space observatory carries a 1.1 m Gregorian telescope and was launched into space in 2001 (Nordh et al 2003;Hjalmarson et al 2003). It is located in a polar orbit at 600 km altitude.…”

Section: Odinmentioning

confidence: 99%

“…At 557 and 576 GHz, the FWHM is 126 ′′ and 118 ′′ respectively. The spectra were converted to a T mb scale using a main beam efficiency, η mb = 0.9, as measured from Jupiter observations (Hjalmarson et al 2003). The CO (5−4) observations, suffered from frequency drift and have, for that reason, been calibrated, using atmospheric spectral lines, acquired during the time intervals when Odin observed through the Earth's atmosphere .…”

Section: Odinmentioning

confidence: 99%

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Herschelobservations of the Herbig-Haro objects HH 52-54

Bjerkeli

Liseau

Nisini

et al. 2011

A&A

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Context. The emission from Herbig-Haro objects and supersonic molecular outflows is understood as cooling radiation behind shocks, which are initiated by a (proto-)stellar wind or jet. Within a given object, one often observes both dissociative (J-type) and non-dissociative (C-type) shocks, owing to the collective effects of internally varying shock velocities. Aims. We aim at the observational estimation of the relative contribution to the cooling by CO and H 2 O, as this provides decisive information for understanding the oxygen chemistry behind interstellar shock waves. Methods. The high sensitivity of HIFI, in combination with its high spectral resolution capability, allowed us to trace the H 2 O outflow wings at an unprecedented signal-to-noise ratio. From the observation of spectrally resolved H 2 O and CO lines in the HH52-54 system, both from space and from the ground, we arrived at the spatial and velocity distribution of the molecular outflow gas. Solving the statistical equilibrium and non-LTE radiative transfer equations provides us with estimates of the physical parameters of this gas, including the cooling rate ratios of the species. The radiative transfer is based on an accelerated lambda iteration code, where we use the fact that variable shock strengths, distributed along the front, are naturally implied by a curved surface. Results. Based on observations of CO and H 2 O spectral lines, we conclude that the emission is confined to the HH54 region. The quantitative analysis of our observations favours a ratio of the CO-to-H 2 O-cooling-rate 1. Formally, we derived the ratio Λ(CO)/Λ(o-H 2 O) = 10, which is in good agreement with earlier determination of 7 based on ISO-LWS observations. From the bestfit model to the CO emission, we arrive at an H 2 O abundance close to 1 × 10 −5 . The line profiles exhibit two components, one that is triangular and another that is a superposed, additional feature. This additional feature is likely to find its origin in a region that is smaller than the beam where the ortho-water abundance is smaller than in the quiescent gas. Conclusions. Comparison with recent shock models indicate that a planar shock cannot easily explain the observed line strengths and triangular line profiles. We conclude that the geometry can play an important role. Although abundances support a scenario where J-type shocks are present, higher cooling rate ratios are derived than predicted by these types of shocks.

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Section: Odinmentioning

confidence: 99%

Section: Odinmentioning

confidence: 99%

Herschelobservations of the Herbig-Haro objects HH 52-54

Bjerkeli

Liseau

Nisini

et al. 2011

A&A

Self Cite

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“…Observation modes include both limb scanning via satellite nodding (Earth atmosphere) and space viewing, and cover a large cadre of important aeronomy and astronomy spectroscopic lines. After more than six years of operation (still continuing at time of writing despite a variety of operational problems [43]) Odin has monitored chlorine and ozone in the stratosphere longer than any other satellite, has observed more than 70 new spectral lines, looked at emission from more than a dozen comets and measured water in the upper atmosphere of Mars [44], [45].…”

Section: Historic and Operational Thz Space Missionsmentioning

confidence: 99%

THz Instruments for Space

Siegel

2007

IEEE Trans. Antennas Propagat.

240

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Terahertz technology has been driven largely by applications in astronomy and space science. For more than three decades cosmochemists, molecular spectroscopists, astrophysicists, and Earth and planetary scientists have used submillimeter-wave or terahertz sensors to identify, catalog and map lightweight gases, atoms and molecules in Earth and planetary atmospheres, in regions of interstellar dust and star formation, and in new and old galaxies, back to the earliest days of the universe, from both ground based and more recently, orbital platforms. The past ten years have witnessed the launch and successful deployment of three satellite instruments with spectral line heterodyne receivers above 300 GHz (SWAS, Odin, and MIRO) and a fourth platform, Aura MLS, that reaches to 2520 GHz, crossing the terahertz threshold from the microwave side for the first time. The former Soviet Union launched the first bolometric detectors for the submillimeter way back in 1974 and operated the first space based submillimeter wave telescope on the Salyut 6 station for four months in 1978. In addition, continuum, Fourier transform and spectrophotometer instruments on IRAS, ISO, COBE, the recent Spitzer Space Telescope and Japan's Akari satellite have all encroached into the submillimeter from the infrared using direct detection bolometers or photoconductors. At least two more major satellites carrying submillimeter wave instruments are nearing completion, Herschel and Planck, and many more are on the drawing boards in international and national space organizations such as NASA, ESA, DLR, CNES, and JAXA. This paper reviews some of the programs that have been proposed, completed and are still envisioned for space applications in the submillimeter and terahertz spectral range.Index Terms-Space instruments, submillimeter wave, terahertz (THz).

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“…The Voigt profile (Olver et al 2010, print companion to the NIST Digital Library of Mathematical Functions, http: //dlmf.nist.gov/), i.e. the convolution of a Lorentzian and Gaussian profile, is ubiquitous in many branches of physics including astrophysics, e.g., Peraiah (2002); Heng (2017). From a computational point it is more convenient to consider the Voigt function K(x, y) depending on two variables x and y (essentially the distance from the center peak and the ratio of the Lorentz to Gauss width) and the complex error function w(x +iy), whose real part gives the Voigt function.…”

Section: Introductionmentioning

confidence: 99%

“…Highly accurate codes such as Poppe & Wijers (1990a,b) (14 significant digits stated accuracy) and Zaghloul & Ali (2011) (20 significant digits) or arbitrary precision codes (Boyer & Lynas-Gray 2014;Molin 2011) are indispensable for tests of an algorithm's accuracy, but not necessarily fast. High resolution line-by-line (lbl) radiative transfer modeling (Bailey & Kedziora-Chudczer 2012;Schreier et al 2014) presents E-mail: franz.schreier@dlr.de a "million-to billion-line challenge" (Grimm & Heng 2015;Heng 2017) where numerous Voigt functions have to be evaluated (Rothman et al 2010;Tennyson & Yurchenko 2012) at thousands to millions of frequency grid points and computational speed becomes a prime concern.…”

Section: Introductionmentioning

confidence: 99%

The Voigt and complex error function: Humlíček’s rational approximation generalized

Schreier

2018

Monthly Notices of the Royal Astronomical Society

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Accurate yet efficient computation of the Voigt and complex error function is a challenge since decades in astrophysics and other areas of physics. Rational approximations have attracted considerable attention and are used in many codes, often in combination with other techniques. The 12-term code "cpf12" of Humlíček (1979) achieves an accuracy of five to six significant digits throughout the entire complex plane. Here we generalize this algorithm to a larger (even) number of terms. The n = 16 approximation has a relative accuracy better than 10 −5 for almost the entire complex plane except for very small imaginary values of the argument even without the correction term required for the cpf12 algorithm. With 20 terms the accuracy is better than 10 −6 . In addition to the accuracy assessment we discuss methods for optimization and propose a combination of the 16-term approximation with the asymptotic approximation of Humlíček (1982) for high efficiency.

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Highlights from the first year of Odin observations

Cited by 33 publications

References 32 publications

Herschelobservations of the Herbig-Haro objects HH 52-54

Herschelobservations of the Herbig-Haro objects HH 52-54

THz Instruments for Space

The Voigt and complex error function: Humlíček’s rational approximation generalized

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