| 1. |
- de Graauw, Th., et al.
(författare)
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The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L6-
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Tidskriftsartikel (refereegranskat)abstract
- Aims: This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods: The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results: After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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| 2. |
- Roelfsema, P. R., et al.
(författare)
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In-orbit performance of Herschel-HIFI
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 537
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Tidskriftsartikel (refereegranskat)abstract
- Aims: In this paper the calibration and in-orbit performance of the Heterodyne Instrument for the Far-Infrared (HIFI) is described.Methods: The calibration of HIFI is based on a combination of ground and in-flight tests. Dedicated ground tests to determine those instrument parameters that can only be measured accurately using controlled laboratory stimuli were carried out in the instrument level test (ILT) campaign. Special in-flight tests during the commissioning phase (CoP) and performance verification (PV) allowed the determination of the remaining instrument parameters. The various instrument observing modes, as specified in astronomical observation templates (AOTs), were validated in parallel during PV by observing selected celestial sources.Results: The initial calibration and in-orbit performance of HIFI has been established. A first estimate of the calibration budget is given. The overall in-flight instrument performance agrees with the original specification. Issues remain at only a few frequencies. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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| 3. |
- Marseille, M. G., et al.
(författare)
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Water abundances in high-mass protostellar envelopes : Herschel observations with HIFI
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521, s. L32-
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Tidskriftsartikel (refereegranskat)abstract
- Aims: We derive the dense core structure and the water abundance in four massive star-forming regions in the hope of understanding the earliest stages of massive star formation. Methods: We present Herschel/HIFI observations of the para-H2O 111-000 and 202-111 and the para-H_218O 111-000 transitions. The envelope contribution to the line profiles is separated from contributions by outflows and foreground clouds. The envelope contribution is modeled with Monte-Carlo radiative transfer codes for dust and molecular lines (MC3D and RATRAN), and the water abundance and the turbulent velocity width as free parameters. Results: While the outflows are mostly seen in emission in high-J lines, envelopes are seen in absorption in ground-state lines, which are almost saturated. The derived water abundances range from 5×10-10 to 4×10-8 in the outer envelopes. We detect cold clouds surrounding the protostar envelope, thanks to the very high quality of the Herschel/HIFI data and the unique ability of water to probe them. Several foreground clouds are also detected along the line of sight. Conclusions: The low H2O abundances in massive dense cores are in accordance with the expectation that high densities and low temperatures lead to freeze-out of water on dust grains. The spread in abundance values is not clearly linked to physical properties of the sources. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation of NASA.Appendix (pages 6 to 7) is only available in electronic form at http://www.aanda.org
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| 4. |
- Benz, A. O., et al.
(författare)
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Hydrides in young stellar objects : Radiation tracers in a protostar-disk-outflow system
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521, s. L35-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Hydrides of the most abundant heavier elements are fundamental molecules in cosmic chemistry. Some of them trace gas irradiated by UV or X-rays. Aims: We explore the abundances of major hydrides in W3 IRS5, a prototypical region of high-mass star formation. Methods: W3 IRS5 was observed by HIFI on the Herschel Space Observatory with deep integration (≃2500 s) in 8 spectral regions. Results: The target lines including CH, NH, H3O+, and the new molecules SH+, H2O+, and OH+ are detected. The H2O+ and OH+ J = 1-0 lines are found mostly in absorption, but also appear to exhibit weak emission (P-Cyg-like). Emission requires high density, thus originates most likely near the protostar. This is corroborated by the absence of line shifts relative to the young stellar object (YSO). In addition, H2O+ and OH+ also contain strong absorption components at a velocity shifted relative to W3 IRS5, which are attributed to foreground clouds. Conclusions: The molecular column densities derived from observations correlate well with the predictions of a model that assumes the main emission region is in outflow walls, heated and irradiated by protostellar UV radiation. Herschel is an ESA space observatory with science instruments provided by a European-led Principal Investigator consortia and with important participation from NASA.Appendix (page 5) is only available in electronic form at http://www.aanda.org
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| 5. |
- Bruderer, S., et al.
(författare)
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Herschel/HIFI detections of hydrides towards AFGL 2591. Envelope emission versus tenuous cloud absorption
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521, s. L44-
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Tidskriftsartikel (refereegranskat)abstract
- The Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory allows the first observations of light diatomic molecules at high spectral resolution and in multiple transitions. Here, we report deep integrations using HIFI in different lines of hydrides towards the high-mass star forming region AFGL 2591. Detected are CH, CH+, NH, OH+, H2O+, while NH+ and SH+ have not been detected. All molecules except for CH and CH+ are seen in absorption with low excitation temperatures and at velocities different from the systemic velocity of the protostellar envelope. Surprisingly, the CH(JF,P = 3/22,- - 1/21,+ ) and CH+(J = 1-0, J = 2-1) lines are detected in emission at the systemic velocity. We can assign the absorption features to a foreground cloud and an outflow lobe, while the CH and CH+ emission stems from the envelope. The observed abundance and excitation of CH and CH+ can be explained in the scenario of FUV irradiated outflow walls, where a cavity etched out by the outflow allows protostellar FUV photons to irradiate and heat the envelope at larger distances driving the chemical reactions that produce these molecules. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Apppendices and Table 1 (pages 6 to 7) are only available in electronic form at http://www.aanda.org
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| 6. |
- Huijben, Jilske A., et al.
(författare)
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Development of a quality indicator set to measure and improve quality of ICU care for patients with traumatic brain injury
- 2019
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Ingår i: Critical Care. - : BioMed Central. - 1364-8535 .- 1466-609X. ; 23
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Tidskriftsartikel (refereegranskat)abstract
- Background: We aimed to develop a set of quality indicators for patients with traumatic brain injury (TBI) in intensive care units (ICUs) across Europe and to explore barriers and facilitators for implementation of these quality indicators.Methods: A preliminary list of 66 quality indicators was developed, based on current guidelines, existing practice variation, and clinical expertise in TBI management at the ICU. Eight TBI experts of the Advisory Committee preselected the quality indicators during a first Delphi round. A larger Europe-wide expert panel was recruited for the next two Delphi rounds. Quality indicator definitions were evaluated on four criteria: validity (better performance on the indicator reflects better processes of care and leads to better patient outcome), feasibility (data are available or easy to obtain), discriminability (variability in clinical practice), and actionability (professionals can act based on the indicator). Experts scored indicators on a 5-point Likert scale delivered by an electronic survey tool.Results. The expert panel consisted of 50 experts from 18 countries across Europe, mostly intensivists (N=24, 48%) and neurosurgeons (N=7, 14%). Experts agreed on a final set of 42 indicators to assess quality of ICU care: 17 structure indicators, 16 process indicators, and 9 outcome indicators. Experts are motivated to implement this finally proposed set (N=49, 98%) and indicated routine measurement in registries (N=41, 82%), benchmarking (N=42, 84%), and quality improvement programs (N=41, 82%) as future steps. Administrative burden was indicated as the most important barrier for implementation of the indicator set (N=48, 98%).Conclusions: This Delphi consensus study gives insight in which quality indicators have the potential to improve quality of TBI care at European ICUs. The proposed quality indicator set is recommended to be used across Europe for registry purposes to gain insight in current ICU practices and outcomes of patients with TBI. This indicator set may become an important tool to support benchmarking and quality improvement programs for patients with TBI in the future.
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| 7. |
- Roelfsema, P. R., et al.
(författare)
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SPICA-A Large Cryogenic Infrared Space Telescope : Unveiling the Obscured Universe
- 2018
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Ingår i: Publications Astronomical Society of Australia. - : Cambridge University Press (CUP). - 1323-3580 .- 1448-6083. ; 35
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Tidskriftsartikel (refereegranskat)abstract
- Measurements in the infrared wavelength domain allow direct assessment of the physical state and energy balance of cool matter in space, enabling the detailed study of the processes that govern the formation and evolution of stars and planetary systems in galaxies over cosmic time. Previous infrared missions revealed a great deal about the obscured Universe, but were hampered by limited sensitivity. SPICA takes the next step in infrared observational capability by combining a large 2.5-meter diameter telescope. cooled to below 8 K, with instruments employing ultra-sensitive detectors. A combination of passive cooling and mechanical coolers will be used to cool both the telescope and the instruments. With mechanical coolers the mission lifetime is not limited by the supply of cryogen. With the combination of low telescope background and instruments with state-of-the-art detectors SPICA provides a huge advance on the capabilities of previous missions. SPICA instruments offer spectral resolving power ranging from R similar to 50 through 11 000 in the 17-230 mu m domain and R similar to 28.000 spectroscopy between 12 and 18 mu m.SPICA will provide efficient 30-37 mu m broad band mapping, and small field spectroscopic and polarimetric imaging at 100, 200 and 350 mu m. SPICA will provide infrared spectroscopy with an unprecedented sensitivity of similar to 5 x 10(-20) W m (-2) (5 sigma/1 h)-over two orders of magnitude improvement over what earlier missions. This exceptional performance leap, will open entirely new domains in infrared astronomy; galaxy evolution and metal production over cosmic time, dust formation and evolution from very early epochs onwards, the formation history of planetary systems.
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| 8. |
- Teyssier, D., et al.
(författare)
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Herschel/HIFI In-flight commissioning and performance
- 2010
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Ingår i: 21st International Symposium on Space Terahertz Technology 2010, ISSTT 2010; Oxford; United Kingdom; 23 March 2010 through 25 March 2010. - 9781617823626 ; , s. 23-28
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Konferensbidrag (refereegranskat)abstract
- The Herschel Space Observatory was successfully launched on the 14th of May, 2009, lifting into space the Heterodyne Instrument for the Far-Infrared (HIFI). After the standard early orbit operations on the Space-craft, the instrument was switched on for the first time on the 24th of May, kicking off an instrument Commissioning period of more than a month and a half. We present here the outcome of this Commissioning campaign, including the measured in-flight performance of the instrument. Among the challenges encountered during this period was the need to optimize the stability of the signal provided by the Local Oscillator (LO) chains in some of the frequency bands, in particular that covering the singly Ionized Carbon (C+) line at the upper edge of the HIFI range, and one of the backbones of the science program of the instrument. The same concept also allowed significant improvements in the upper end of the 3b LO chain. Another noticeable achievement was the very good co-alignment measured between the mixer beams in the respective H and V polarizations offered by HIFI, allowing for more than a simple build-in redundancy, as the observing efficiency will really benefits from the combination of the two mixers.
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| 9. |
- Walker, Steven M, et al.
(författare)
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Molecular Subgroup of Primary Prostate Cancer Presenting with Metastatic Biology
- 2017
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Ingår i: European Urology. - : Elsevier BV. - 0302-2838 .- 1873-7560. ; 72:4, s. 509-518
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Approximately 4-25% of patients with early prostate cancer develop disease recurrence following radical prostatectomy.OBJECTIVE: To identify a molecular subgroup of prostate cancers with metastatic potential at presentation resulting in a high risk of recurrence following radical prostatectomy.DESIGN, SETTING, AND PARTICIPANTS: Unsupervised hierarchical clustering was performed using gene expression data from 70 primary resections, 31 metastatic lymph nodes, and 25 normal prostate samples. Independent assay validation was performed using 322 radical prostatectomy samples from four sites with a mean follow-up of 50.3 months.OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Molecular subgroups were identified using unsupervised hierarchical clustering. A partial least squares approach was used to generate a gene expression assay. Relationships with outcome (time to biochemical and metastatic recurrence) were analysed using multivariable Cox regression and log-rank analysis.RESULTS AND LIMITATIONS: A molecular subgroup of primary prostate cancer with biology similar to metastatic disease was identified. A 70-transcript signature (metastatic assay) was developed and independently validated in the radical prostatectomy samples. Metastatic assay positive patients had increased risk of biochemical recurrence (multivariable hazard ratio [HR] 1.62 [1.13-2.33]; p=0.0092) and metastatic recurrence (multivariable HR=3.20 [1.76-5.80]; p=0.0001). A combined model with Cancer of the Prostate Risk Assessment post surgical (CAPRA-S) identified patients at an increased risk of biochemical and metastatic recurrence superior to either model alone (HR=2.67 [1.90-3.75]; p<0.0001 and HR=7.53 [4.13-13.73]; p<0.0001, respectively). The retrospective nature of the study is acknowledged as a potential limitation.CONCLUSIONS: The metastatic assay may identify a molecular subgroup of primary prostate cancers with metastatic potential.PATIENT SUMMARY: The metastatic assay may improve the ability to detect patients at risk of metastatic recurrence following radical prostatectomy. The impact of adjuvant therapies should be assessed in this higher-risk population.
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| 10. |
- Bergin, E. A., et al.
(författare)
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Sensitive limits on the abundance of cold water vapor in the DM Tauri protoplanetary disk
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521, s. L33-
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Tidskriftsartikel (refereegranskat)abstract
- We performed a sensitive search for the ground-state emission lines of ortho-and para-water vapor in the DM Tau protoplanetary disk using the Herschel/HIFI instrument. No strong lines are detected down to 3 sigma levels in 0.5 km s(-1) channels of 4.2 mK for the 1(10)-1(01) line and 12.6 mK for the 1(11)-0(00) line. We report a very tentative detection, however, of the 1(10)-1(01) line in the wide band spectrometer, with a strength of T-mb = 2.7 mK, a width of 5.6 km s(-1) and an integrated intensity of 16.0 mK km s(-1). The latter constitutes a 6 sigma detection. Regardless of the reality of this tentative detection, model calculations indicate that our sensitive limits on the line strengths preclude efficient desorption of water in the UV illuminated regions of the disk. We hypothesize that more than 95-99% of the water ice is locked up in coagulated grains that have settled to the midplane.
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| 11. |
- Harwit, M., et al.
(författare)
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Polarisation observations of VY Canis Majoris H2O 5(32)-4(41) 620.701 GHz maser emission with HIFI
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521, s. L51-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. Aims. We have aimed to elucidate the nature and structure of the VY CMa water vapour masers in part by observationally testing a theoretical prediction of the relative strengths of the 620.701 GHz and the 22.235 GHz maser components of ortho H2O. Methods. In its high-resolution mode (HRS) the Herschel Heterodyne Instrument for the Far Infrared (HIFI) offers a frequency resolution of 0.125 MHz, corresponding to a line-of-sight velocity of 0.06 km s(-1), which we employed to obtain the strength and linear polarisation of maser spikes in the spectrum of VY CMa at 620.701 GHz. Simultaneous ground based observations of the 22.235 GHz maser with the Max-Planck-Institut fur Radioastronomie 100-m telescope at Effelsberg, provided a ratio of 620.701 GHz to 22.235 GHz emission. Results. We report the first astronomical detection to date of H2O maser emission at 620.701 GHz. In VY CMa both the 620.701 and the 22.235 GHz polarisation are weak. At 620.701 GHz the maser peaks are superposed on what appears to be a broad emission component, jointly ejected from the star. We observed the 620.701 GHz emission at two epochs 21 days apart, both to measure the potential direction of linearly polarised maser components and to obtain a measure of the longevity of these components. Although we do not detect significant polarisation levels in the core of the line, they rise up to approximately 6% in its wings.
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| 12. |
- Harwit, M., et al.
(författare)
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Polarisation observations of VY Canis Majoris H2O 532-441 620.701 GHz maser emission with HIFI
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L51-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. Aims. We have aimed to elucidate the nature and structure of the VY CMa water vapour masers in part by observationally testing a theoretical prediction of the relative strengths of the 620.701 GHz and the 22.235 GHz maser components of ortho H2O. Methods. In its high-resolution mode (HRS) the Herschel Heterodyne Instrument for the Far Infrared (HIFI) offers a frequency resolution of 0.125 MHz, corresponding to a line-of-sight velocity of 0.06 km s(-1), which we employed to obtain the strength and linear polarisation of maser spikes in the spectrum of VY CMa at 620.701 GHz. Simultaneous ground based observations of the 22.235 GHz maser with the Max-Planck-Institut fur Radioastronomie 100-m telescope at Effelsberg, provided a ratio of 620.701 GHz to 22.235 GHz emission. Results. We report the first astronomical detection to date of H2O maser emission at 620.701 GHz. In VY CMa both the 620.701 and the 22.235 GHz polarisation are weak. At 620.701 GHz the maser peaks are superposed on what appears to be a broad emission component, jointly ejected from the star. We observed the 620.701 GHz emission at two epochs 21 days apart, both to measure the potential direction of linearly polarised maser components and to obtain a measure of the longevity of these components. Although we do not detect significant polarisation levels in the core of the line, they rise up to approximately 6% in its wings.
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| 13. |
- Johnstone, D., et al.
(författare)
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Herschel/HIFI spectroscopy of the intermediate mass protostar NGC7129 FIRS 2
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521, s. L41-
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Tidskriftsartikel (refereegranskat)abstract
- Herschel/HIFI observations of water from the intermediate mass protostar NGC 7129 FIRS 2 provide a powerful diagnostic of the physical conditions in this star formation environment. Six spectral settings, covering four (H2O)-O-16 and two (H2O)-O-18 lines, were observed and all but one (H2O)-O-18 line were detected. The four (H2O)-O-16 lines discussed here share a similar morphology: a narrower, approximate to 6kms(-1), component centered slightly redward of the systemic velocity of NGC7129 FIRS 2 and a much broader, approximate to 25 km s(-1) component centered blueward and likely associated with powerful outflows. The narrower components are consistent with emission from water arising in the envelope around the intermediate mass protostar, and the abundance of H2O is constrained to approximate to 10(-7) for the outer envelope. Additionally, the presence of a narrow self-absorption component for the lowest energy lines is likely due to self-absorption from colder water in the outer envelope. The broader component, where the H2O/CO relative abundance is found to be approximate to 0.2, appears to be tracing the same energetic region that produces strong CO emission at high J.
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| 14. |
- Neufeld, D. A., et al.
(författare)
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Discovery of water vapour in the carbon star V Cygni from observations with Herschel/HIFI
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L5-
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of water vapour toward the carbon star V Cygni. We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 1(11)-0(00) para-water transition at 1113.3430 GHz in the upper sideband of the Band 4b receiver. The observed spectral line profile is nearly parabolic, but with a slight asymmetry associated with blueshifted absorption, and the integrated antenna temperature is 1.69 +/- 0.17 K km s(-1). This detection of thermal water vapour emission, carried out as part of a small survey of water in carbon-rich stars, is only the second such detection toward a carbon-rich AGB star, the first having been obtained by the Submillimeter Wave Astronomy Satellite toward IRC+ 10216. For an assumed ortho-to-para ratio of 3 for water, the observed line intensity implies a water outflow rate similar to 3-6 x 10(-5) Earth masses per year and a water abundance relative to H-2 of similar to 2-5 x 10(-6). This value is a factor of at least 10(4) larger than the expected photospheric abundance in a carbon-rich environment, and - as in IRC+ 10216 - raises the intriguing possibility that the observed water is produced by the vapourisation of orbiting comets or dwarf planets. However, observations of the single line observed to date do not permit us to place strong constraints upon the spatial distribution or origin of the observed water, but future observations of additional transitions will allow us to determine the inner radius of the H2O-emitting zone, and the H2O ortho-to-para ratio, and thereby to place important constraints upon the origin of the observed water emission.
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| 15. |
- van Tulder, M W, et al.
(författare)
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WITHDRAWN: Lumbar supports for prevention and treatment of low-back pain.
- 2006
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Ingår i: Cochrane database of systematic reviews (Online). - 1469-493X. ; :2
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Tidskriftsartikel (refereegranskat)abstract
- Lumbar supports are used in the treatment of low back pain patients to make the impairment and disability vanish or decrease. Lumbar supports are also used to prevent the onset of low back pain (primary prevention) or to prevent recurrences of a low back pain episode (secondary prevention).
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| 16. |
- Wampfler, S. F., et al.
(författare)
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Herschel observations of the hydroxyl radical (OH) in young stellar objects
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521, s. L36-
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Tidskriftsartikel (refereegranskat)abstract
- Aims: “Water In Star-forming regions with Herschel” (WISH) is a Herschel key program investigating the water chemistry in young stellar objects (YSOs) during protostellar evolution. Hydroxyl (OH) is one of the reactants in the chemical network most closely linked to the formation and destruction of H2O. High-temperature (T ⪆ 250 K) chemistry connects OH and H2O through the OH + H2 Leftrightarrow H2O + H reactions. Formation of H2O from OH is efficient in the high-temperature regime found in shocks and the innermost part of protostellar envelopes. Moreover, in the presence of UV photons, OH can be produced from the photo-dissociation of H2O through H2O + γUV Rightarrow OH + H. Methods: High-resolution spectroscopy of the 163.12 μm triplet of OH towards HH 46 and NGC 1333 IRAS 2A was carried out with the Heterodyne Instrument for the Far Infrared (HIFI) on board the Herschel Space Observatory. The low- and intermediate-mass protostars HH 46, TMR 1, IRAS 15398-3359, DK Cha, NGC 7129 FIRS 2, and NGC 1333 IRAS 2A were observed with the Photodetector Array Camera and Spectrometer (PACS) on Herschel in four transitions of OH and two [O i] lines. Results: The OH transitions at 79, 84, 119, and 163 μm and [O i] emission at 63 and 145 μm were detected with PACS towards the class I low-mass YSOs as well as the intermediate-mass and class I Herbig Ae sources. No OH emission was detected from the class 0 YSO NGC 1333 IRAS 2A, though the 119 μm was detected in absorption. With HIFI, the 163.12 μm was not detected from HH 46 and only tentatively detected from NGC 1333 IRAS 2A. The combination of the PACS and HIFI results for HH 46 constrains the line width (FWHM ⪆ 11 km s-1) and indicates that the OH emission likely originates from shocked gas. This scenario is supported by trends of the OH flux increasing with the [O i] flux and the bolometric luminosity, as found in our sample. Similar OH line ratios for most sources suggest that OH has comparable excitation temperatures despite the different physical properties of the sources. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices (page 6) are only available in electronic form at http://www.aanda.org
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| 17. |
- Wiedner, M.C., et al.
(författare)
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A Proposed Heterodyne Receiver for the Origins Space Telescope
- 2018
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Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 8:6, s. 558-571
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Tidskriftsartikel (refereegranskat)abstract
- The HEterodyne Receiver for the Origins Space Telescope (HERO) is a proposed design for a heterodyne focal plane array for a large space mission. The Origins Space Telescope (OST) is one of the four missions selected to be studied by NASA for the 2020 Astronomy and Astrophysics Decadal survey. HERO is designed to observe the trail of water from the interstellar medium (ISM) to disks around protostars. In Concept 1, HERO provides continuous frequency coverage from 468 to 2700 GHz in five bands and a sixth band to cover 4700 GHz. Most bands include 2 × 64 pixels providing at least an order of magnitude higher mapping speeds than available with today's instruments. Receiver sensitivities are expected to be close to the quantum limit. HERO Concept 2, highly constrained by cost and denoted Little-HERO, includes four bands with continuous coverage from 486 to 2700 GHz and with focal plane arrays having only 2 × 9 pixels per band. Both of these THz receiver concepts will be described and the designs will be motivated by the science drivers, the space craft constraints and the latest technological developments. The HERO design builds on the highly successful Herschel/Heterodyne Instrument for the Far-Infrared, on Stratospheric Observatory for Far-Infrared Astronomy/upGREAT and many other heterodyne receivers, but surpasses these in terms of frequency coverage, array size and sensitivity, thanks to the latest technical advances. HERO can be considered an example of a new generation of heterodyne focal plane arrays for future space missions.
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| 18. |
- Wiedner, M.C., et al.
(författare)
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Heterodyn receiver for the Origins Space Telescope concept 2
- 2018
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 10698
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Konferensbidrag (refereegranskat)abstract
- The Origins Space Telescope (OST) is a NASA study for a large satellite mission to be submitted to the 2020 Decadal Review. The proposed satellite has a fleet of instruments including the HEterodyne Receivers for OST (HERO). HERO is designed around the quest to follow the trail of water from the ISM to disks around protostars and planets. HERO will perform high-spectral resolution measurements with 2x9 pixel focal plane arrays at any frequency between 468GHz to 2,700GHz (617 to 111 μm). HERO builds on the successful Herschel/HIFI heritage, as well as recent technological innovations, allowing it to surpass any prior heterodyne instrument in terms of sensitivity and spectral coverage.
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| 19. |
- Wiedner, M.C., et al.
(författare)
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Heterodyne Receiver for Origins
- 2021
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - 2329-4221 .- 2329-4124. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The Heterodyne Receiver for Origins (HERO) is the first detailed study of a heterodyne focal plane array receiver for space applications. HERO gives the Origins Space Telescope the capability to observe at very high spectral resolution (R = 107) over an unprecedentedly large far-infrared (FIR) wavelengths range (111 to 617 μm) with high sensitivity, with simultaneous dual polarization and dual-frequency band operation. The design is based on prior successful heterodyne receivers, such as Heterodyne Instrument for the Far-Infrared/Herschel, but surpasses it by one to two orders of magnitude by exploiting the latest technological developments. Innovative components are used to keep the required satellite resources low and thus allowing for the first time a convincing design of a large format heterodyne array receiver for space. HERO on Origins is a unique tool to explore the FIR universe and extends the enormous potential of submillimeter astronomical spectroscopy into new areas of astronomical research.
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| 21. |
- Wiedner, M.C., et al.
(författare)
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The origins space telescope and the heterodyne receiver for origins (HERO)
- 2019
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Ingår i: ISSTT 2019 - 30th International Symposium on Space Terahertz Technology, Proceedings Book. ; , s. 204-207
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Konferensbidrag (refereegranskat)abstract
- The Origins Space Telescope is one of four large mission concept studies carried out by NASA for the 2020 Decadal survey. Origins is a far-infrared telescope designed to understand the evolution of galaxies and black holes, to follow the trail of water from protostars to habitable planets and to search for biosignatures in the atmospheres of exoplanets. The Heterodyne Receiver for Origins (HERO) is the high spectral resolution receiver. It is the first heterodyne array receiver designed to fly on a satellite and an example for possible future focal plane arrays for space. HERO has focal plane arrays with nine pixels in two polarization. HERO covers a large frequency range between 486 and 2700 GHz in only 4 frequency bands, requiring local oscillators with fractional bandwidth of 45%. HERO uses the best superconducting mixers with noise temperatures between 1 and 3 hf/k and an intermediate bandwidth of 6 to 8 GHz. HERO can carry out dual polarization and dual-frequency observations. The major challenges for the HERO design are the low cooling power and the low electrical power available on a spacecraft, which impact the choice of the cryogenic amplifiers and backends. SiGe cryogenic amplifiers with a consumption of less than 0.5 mW, as well as CMOS spectrometers with a power consumption below 2W are the baseline for HERO. The development plan includes broadband (45%) multiplier-amplifier chains, low noise mixers (1-3 hf/k), low-power consuming (< 05.mW) cryogenic amplifiers and low-power consuming spectrometer backends (< 2W).
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| 22. |
- Yildiz, U. A., et al.
(författare)
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Herschel/HIFI observations of high-J CO lines in the NGC 1333 low-mass star-forming region
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521, s. L40-
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Tidskriftsartikel (refereegranskat)abstract
- Herschel/HIFI observations of high-J lines (up to J(u) = 10) of (CO)-C-12, (CO)-C-13 and (CO)-O-18 are presented toward three deeply embedded low-mass protostars, NGC 1333 IRAS 2A, IRAS 4A, and IRAS 4B, obtained as part of the Water In Star-forming regions with Herschel (WISH) key program. The spectrally-resolved HIFI data are complemented by ground-based observations of lower-J CO and isotopologue lines. The (CO)-C-12 10-9 profiles are dominated by broad (FWHM 25-30 km s(-1)) emission. Radiative transfer models are used to constrain the temperature of this shocked gas to 100-200 K. Several CO and (CO)-C-13 line profiles also reveal a medium-broad component (FWHM5-10 km s(-1)), seen prominently in H2O lines. Column densities for both components are presented, providing a reference for determining abundances of other molecules in the same gas. The narrow (CO)-O-18 9-8 lines probe the warmer part of the quiescent envelope. Their intensities require a jump in the CO abundance at an evaporation temperature around 25 K, thus providing new direct evidence for a CO ice evaporation zone around low-mass protostars.
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