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Book: Schlußbericht des Vorhabens: "Untersuchungen der Struktur und Kollimation von T Tauri-Jets mit dem HST"

Eislöffel, Jochen

2007

Title variant	Investigations of the structure and collimation of T Tauri-jets with the HST ; Untersuchungen der Struktur und Kollimation von T Tauri-Jets mit dem HST
Author's details	Jochen Eislöffel
Language	German
Size	[13] S., graph. Darst.
Publisher	Thüringer Landessternwarte
Publishing place	Tautenburg
Document type	Book
Note	Förderkennzeichen BMBF 50 OR 0009. - Engl. Berichtsbl. u.d.T.: Investigations of the structure and collimation of T Tauri-jets with the HST ; Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden
Database	Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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Article ; Online: Cool, warm and hot outflows from CTTS

Schneider P. C. / Eislöffel J. / Güdel M. / Günther H.M. / Herczeg G. / Robrade J. / Schmitt J.H.M.M.

EPJ Web of Conferences, Vol 64, p

The FUV view of DG Tau

2014 Volume 08007

Abstract: Classical T Tauri stars (CTTSs) drive strong outflows with temperatures from about 103 K up to a few 106 K. These outflows regulate the angular momentum balance and are therefore tightly related to the accretion process. However, the outflow driving and ... ...

Abstract	Classical T Tauri stars (CTTSs) drive strong outflows with temperatures from about 103 K up to a few 106 K. These outflows regulate the angular momentum balance and are therefore tightly related to the accretion process. However, the outflow driving and heating mechanisms are not well understood. We present new HST data of the “prototypical” jet-driving CTTS DG Tau tracing the low-temperature outflow with fluorescently excited far-UV molecular hydrogen emission and the high-temperature part with C IV emission. We find that the spatial distribution of the low-temperature plasma is V-shaped consistent with molecular disk-wind models. Low-velocity shocks (vshock ~ 30 km s−1) are probably the pumping source for the FUV H2 lines. The hot plasma (T > 105 K) is located close to the jet axis at a distance of 40 AU from the driving source and spatially offset from standard (optical) jet-tracers like [S II] or [O I]. It does not show any hints for proper-motion contrasting typical jet properties. The high-temperature plasma is unlikely caused by a hot stellar wind and we propose that the stationary heating is caused by internal shocks or magnetic reconnection.
Keywords	Physics ; QC1-999 ; Science ; Q ; DOAJ:Physics (General) ; DOAJ:Physics and Astronomy
Subject code	520
Language	English
Publishing date	2014-01-01T00:00:00Z
Publisher	EDP Sciences
Document type	Article ; Online
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Book: Untersuchungen der Klasse 0-Quellen und ihrer Ausströmungen mit ISO

Eislöffel, Jochen / Froebrich, Dirk

Schlußbericht des Vorhabens

2003

Title variant	Schlußbericht des Vorhabens: "Untersuchungen der Klasse 0-Quellen und ihrer Ausströmungen mit ISO"
Author's details	Jochen Eislöffel; Dirk Froebrich
Language	German
Size	[12] S, graph. Darst
Publisher	Thüringer Landessternwarte
Publishing place	Tautenburg
Document type	Book
Note	Contract BMBF 50 OR9904 9 ; Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden
Database	Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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Article ; Online: Sub-arcsecond imaging with the International LOFAR Telescope

Morabito, L. / Jackson, N. / Mooney, S. / Sweijen, F. / Badole, S. / Kukreti, P. / Venkattu, D. / Groeneveld, C. / Kappes, A. / Bonnassieux, E. / Drabent, A. / Iacobelli, M. / Croston, J. / Best, P. / Bondi, M. / Callingham, J. / Conway, J. / Deller, A. / Hardcastle, M. /

McKean, J. / Miley, G. / Moldon, J. / Röttgering, H. / Tasse, C. / Shimwell, T. / van Weeren, R. / Anderson, J. / Asgekar, A. / Avruch, I. / van Bemmel, I. / Bentum, M. / Bonafede, A. / Brouw, W. / Butcher, H. / Ciardi, B. / Corstanje, A. / Coolen, A. / Damstra, S. / de Gasperin, F. / Duscha, S. / Eislöffel, J. / Engels, D. / Falcke, H. / Garrett, M. / Griessmeier, J. / Gunst, A. / van Haarlem, M. / Hoeft, M. / van der Horst, A. / Jütte, E. / Kadler, M. / Koopmans, L. / Krankowski, A. / Mann, G. / Nelles, A. / Oonk, J. / Orru, E. / Paas, H. / Pandey, V. / Pizzo, R. / Pandey-Pommier, M. / Reich, W. / Rothkaehl, H. / Ruiter, M. / Schwarz, D. / Shulevski, A. / Soida, M. / Tagger, M. / Vocks, C. / Wijers, R. / Wijnholds, S. / Wucknitz, O. / Zarka, P. / Zucca, P.

Astronomy and Astrophysics

2022

Abstract: The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ~2000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 MHz. However, it is technically ... ...

Abstract	The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ~2000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 MHz. However, it is technically and logistically challenging to process LOFAR data at this resolution. To date only a handful of publications have exploited this capability. Here we present a calibration strategy that builds on previous high-resolution work with LOFAR. It is implemented in a pipeline using mostly dedicated LOFAR software tools and the same processing framework as the LOFAR Two-metre Sky Survey (LoTSS). We give an overview of the calibration strategy and discuss the special challenges inherent to enacting high-resolution imaging with LOFAR, and describe the pipeline, which is publicly available, in detail. We demonstrate the calibration strategy by using the pipeline on P205+55, a typical LoTSS pointing with an 8 h observation and 13 international stations. We perform in-field delay calibration, solution referencing to other calibrators in the field, self-calibration of these calibrators, and imaging of example directions of interest in the field. We find that for this specific field and these ionospheric conditions, dispersive delay solutions can be transferred between calibrators up to ~1.5° away, while phase solution transferral works well over ~1°. We also demonstrate a check of the astrometry and flux density scale with the in-field delay calibrator source. Imaging in 17 directions, we find the restoring beam is typically ~0.3′′ ×0.2′′ although this varies slightly over the entire 5 deg2 field of view. We find we can achieve ~80–300 μJy bm−1 image rms noise, which is dependent on the distance from the phase centre; typical values are ~90 μJy bm−1 for the 8 h observation with 48 MHz of bandwidth. Seventy percent of processed sources are detected, and from this we estimate that we should be able to image roughly 900 sources per LoTSS pointing. This equates to ~ 3 million ...
Language	English
Publishing country	de
Document type	Article ; Online
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Article: Low-radio-frequency eclipses of the redback pulsar J2215+5135 observed in the image plane with LOFAR.

Broderick, J W / Fender, R P / Breton, R P / Stewart, A J / Rowlinson, A / Swinbank, J D / Hessels, J W T / Staley, T D / van der Horst, A J / Bell, M E / Carbone, D / Cendes, Y / Corbel, S / Eislöffel, J / Falcke, H / Grießmeier, J-M / Hassall, T E / Jonker, P / Kramer, M /

Kuniyoshi, M / Law, C J / Markoff, S / Molenaar, G J / Pietka, M / Scheers, L H A / Serylak, M / Stappers, B W / Ter Veen, S / van Leeuwen, J / Wijers, R A M J / Wijnands, R / Wise, M W / Zarka, P

Monthly notices of the Royal Astronomical Society

2016 Volume 459, Issue 3, Page(s) 2681–2689

Abstract: The eclipses of certain types of binary millisecond pulsars (i.e. 'black widows' and 'redbacks') are often studied using high-time-resolution, 'beamformed' radio observations. However, they may also be detected in images generated from interferometric ... ...

Abstract	The eclipses of certain types of binary millisecond pulsars (i.e. 'black widows' and 'redbacks') are often studied using high-time-resolution, 'beamformed' radio observations. However, they may also be detected in images generated from interferometric data. As part of a larger imaging project to characterize the variable and transient sky at radio frequencies <200 MHz, we have blindly detected the redback system PSR J2215+5135 as a variable source of interest with the Low-Frequency Array (LOFAR). Using observations with cadences of two weeks - six months, we find preliminary evidence that the eclipse duration is frequency dependent (∝ν
Language	English
Publishing date	2016-07-01
Publishing country	England
Document type	Journal Article
ZDB-ID	207232-4
ISSN	0035-8711
ISSN	0035-8711
DOI	10.1093/mnras/stw794
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Article: New methods to constrain the radio transient rate: results from a survey of four fields with LOFAR.

Monthly notices of the Royal Astronomical Society

2016 Volume 459, Issue 3, Page(s) 3161–3174

Abstract: We report on the results of a search for radio transients between 115 and 190 MHz with the LOw-Frequency ARray (LOFAR). Four fields have been monitored with cadences between 15 min and several months. A total of 151 images were obtained, giving a total ... ...

Abstract	We report on the results of a search for radio transients between 115 and 190 MHz with the LOw-Frequency ARray (LOFAR). Four fields have been monitored with cadences between 15 min and several months. A total of 151 images were obtained, giving a total survey area of 2275 deg
Language	English
Publishing date	2016-07-01
Publishing country	England
Document type	Journal Article
ZDB-ID	207232-4
ISSN	0035-8711
ISSN	0035-8711
DOI	10.1093/mnras/stw539
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: A LOFAR observation of ionospheric scintillation from two simultaneous travelling ionospheric disturbances

Fallows, R. / Forte, B. / Astin, I. / Allbrook, T. / Arnold, A. / Wood, A. / Dorrian, G. / Mevius, M. / Rothkaehl, H. / Matyjasiak, B. / Krankowski, A. / Anderson, J. / Asgekar, A. / Avruch, I. / Bentum, M. / Bisi, M. / Butcher, H. / Ciardi, B. / Dabrowski, B. /

Damstra, S. / de Gasperin, F. / Duscha, S. / Eislöffel, J. / Franzen, T. / Garrett, M. / Grießmeier, J. / Gunst, A. / Hoeft, M. / Hörandel, J. / Iacobelli, M. / Intema, H. / Koopmans, L. / Maat, P. / Mann, G. / Nelles, A. / Paas, H. / Pandey, V. / Reich, W. / Rowlinson, A. / Ruiter, M. / Schwarz, D. / Serylak, M. / Shulevski, A. / Smirnov, O. / Soida, M. / Steinmetz, M. / Thoudam, S. / Toribio, M. / van Ardenne, A. / van Bemmel, I. / van der Wiel, M. / van Haarlem, M. / Vermeulen, R. / Vocks, C. / Wijers, R. / Wucknitz, O. / Zarka, P. / Zucca, P.

Journal of Space Weather and Space Climate

2020

Abstract: This paper presents the results from one of the first observations of ionospheric scintillation taken using the Low-Frequency Array (LOFAR). The observation was of the strong natural radio source Cassiopeia A, taken overnight on 18–19 August 2013, and ... ...

Abstract	This paper presents the results from one of the first observations of ionospheric scintillation taken using the Low-Frequency Array (LOFAR). The observation was of the strong natural radio source Cassiopeia A, taken overnight on 18–19 August 2013, and exhibited moderately strong scattering effects in dynamic spectra of intensity received across an observing bandwidth of 10–80 MHz. Delay-Doppler spectra (the 2-D FFT of the dynamic spectrum) from the first hour of observation showed two discrete parabolic arcs, one with a steep curvature and the other shallow, which can be used to provide estimates of the distance to, and velocity of, the scattering plasma. A cross-correlation analysis of data received by the dense array of stations in the LOFAR “core” reveals two different velocities in the scintillation pattern: a primary velocity of ~20–40 ms−1 with a north-west to south-east direction, associated with the steep parabolic arc and a scattering altitude in the F-region or higher, and a secondary velocity of ~110 ms−1 with a north-east to south-west direction, associated with the shallow arc and a scattering altitude in the D-region. Geomagnetic activity was low in the mid-latitudes at the time, but a weak sub-storm at high latitudes reached its peak at the start of the observation. An analysis of Global Navigation Satellite Systems (GNSS) and ionosonde data from the time reveals a larger-scale travelling ionospheric disturbance (TID), possibly the result of the high-latitude activity, travelling in the north-west to south-east direction, and, simultaneously, a smaller-scale TID travelling in a north-east to south-west direction, which could be associated with atmospheric gravity wave activity. The LOFAR observation shows scattering from both TIDs, at different altitudes and propagating in different directions. To the best of our knowledge this is the first time that such a phenomenon has been reported.
Subject code	551
Language	English
Publishing country	de
Document type	Article ; Online
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Article ; Online: Needle-like structures discovered on positively charged lightning branches.

Hare, B M / Scholten, O / Dwyer, J / Trinh, T N G / Buitink, S / Ter Veen, S / Bonardi, A / Corstanje, A / Falcke, H / Hörandel, J R / Huege, T / Mitra, P / Mulrey, K / Nelles, A / Rachen, J P / Rossetto, L / Schellart, P / Winchen, T / Anderson, J /

Avruch, I M / Bentum, M J / Blaauw, R / Broderick, J W / Brouw, W N / Brüggen, M / Butcher, H R / Ciardi, B / Fallows, R A / de Geus, E / Duscha, S / Eislöffel, J / Garrett, M A / Grießmeier, J M / Gunst, A W / van Haarlem, M P / Hessels, J W T / Hoeft, M / van der Horst, A J / Iacobelli, M / Koopmans, L V E / Krankowski, A / Maat, P / Norden, M J / Paas, H / Pandey-Pommier, M / Pandey, V N / Pekal, R / Pizzo, R / Reich, W / Rothkaehl, H / Röttgering, H J A / Rowlinson, A / Schwarz, D J / Shulevski, A / Sluman, J / Smirnov, O / Soida, M / Tagger, M / Toribio, M C / van Ardenne, A / Wijers, R A M J / van Weeren, R J / Wucknitz, O / Zarka, P / Zucca, P

Nature

2019 Volume 568, Issue 7752, Page(s) 360–363

Abstract: Lightning is a dangerous yet poorly understood natural phenomenon. Lightning forms a network of plasma channels propagating away from the initiation point with both positively and negatively charged ends-called positive and negative ... ...

Abstract	Lightning is a dangerous yet poorly understood natural phenomenon. Lightning forms a network of plasma channels propagating away from the initiation point with both positively and negatively charged ends-called positive and negative leaders
Language	English
Publishing date	2019-04-17
Publishing country	England
Document type	Journal Article
ZDB-ID	120714-3
ISSN	1476-4687 ; 0028-0836
ISSN (online)	1476-4687
ISSN	0028-0836
DOI	10.1038/s41586-019-1086-6
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Article ; Online: LOFAR 144-MHz follow-up observations of GW170817

Broderick, J. / Shimwell, T. / Gourdji, K. / Rowlinson, A. / Nissanke, S. / Hotokezaka, K. / Jonker, P. / Tasse, C. / Hardcastle, M. / Oonk, J. / Fender, R. / Wijers, R. / Shulevski, A. / Stewart, A. / ter Veen, S. / Moss, V. / van der Wiel, M. / Nichols, D. / Piette, A. /

Bell, M. / Carbone, D. / Corbel, S. / Eisloeffel, J. / Griessmeier, J. / Keane, E. / Law, C. / Munoz-Darias, T. / Pietka, M. / Serylak, M. / van der Horst, A. / van Leeuwen, J. / Wijnands, R. / Zarka, P. / Anderson, J. / Bentum, M. / Blaauw, R. / Brouw, W. / Bruggen, M. / Ciardi, B. / de Vos, M. / Duscha, S. / Fallows, R. / Franzen, T. / Garrett, M. / Gunst, A. / Hoeft, M. / Horandel, J. / Iacobelli, M. / Jutte, E. / Koopmans, L. / Krankowski, A. / Maat, P. / Mann, G. / Mulder, H. / Nelles, A. / Paas, H. / Pandey-Pommier, M. / Pekal, R. / Reich, W. / Rottgering, H. / Schwarz, D. / Smirnov, O. / Soida, M. / Toribio, M. / van Haarlem, M. / van Weeren, R. / Vocks, C. / Wucknitz, O. / Zucca, P.

Monthly Notices of the Royal Astronomical Society

2020

Publishing country	de
Document type	Article ; Online
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Article ; Online: Needle-like structures discovered on positively charged lightning branches

Hare, B. / Scholten, O. / Dwyer, J. / Trinh, T. / Buitink, S. / ter Veen, S. / Bonardi, A. / Corstanje, A. / Falcke, H. / Hörandel, J. / Huege, T. / Mitra, P. / Mulrey, K. / Nelles, A. / Rachen, J. / Rossetto, L. / Schellart, P. / Winchen, T. / Anderson, J. /

Avruch, I. / Bentum, M. / Blaauw, R. / Broderick, J. / Brouw, W. / Brüggen, M. / Butcher, H. / Ciardi, B. / Fallows, R. / de Geus, E. / Duscha, S. / Eislöffel, J. / Garrett, M. / Grießmeier, J. / Gunst, A. / van Haarlem, M. / Hessels, J. / Hoeft, M. / van der Horst, A. / Iacobelli, M. / Koopmans, L. / Krankowski, A. / Maat, P. / Norden, M. / Paas, H. / Pandey-Pommier, M. / Pandey, V. / Pekal, R. / Pizzo, R. / Reich, W. / Rothkaehl, H. / Röttgering, H. / Rowlinson, A. / Schwarz, D. / Shulevski, A. / Sluman, J. / Smirnov, O. / Soida, M. / Tagger, M. / Toribio, M. / van Ardenne, A. / Wijers, R. / van Weeren, R. / Wucknitz, O. / Zarka, P. / Zucca, P.

Nature

2019

Abstract	Lightning is a dangerous yet poorly understood natural phenomenon. Lightning forms a network of plasma channels propagating away from the initiation point with both positively and negatively charged ends—called positive and negative leaders1. Negative leaders propagate in discrete steps, emitting copious radio pulses in the 30–300-megahertz frequency band2,3,4,5,6,7,8 that can be remotely sensed and imaged with high spatial and temporal resolution9,10,11. Positive leaders propagate more continuously and thus emit very little high-frequency radiation12. Radio emission from positive leaders has nevertheless been mapped13,14,15, and exhibits a pattern that is different from that of negative leaders11,12,13,16,17. Furthermore, it has been inferred that positive leaders can become transiently disconnected from negative leaders9,12,16,18,19,20, which may lead to current pulses that both reconnect positive leaders to negative leaders11,16,17,20,21,22 and cause multiple cloud-to-ground lightning events1. The disconnection process is thought to be due to negative differential resistance18, but this does not explain why the disconnections form primarily on positive leaders22, or why the current in cloud-to-ground lightning never goes to zero23. Indeed, it is still not understood how positive leaders emit radio-frequency radiation or why they behave differently from negative leaders. Here we report three-dimensional radio interferometric observations of lightning over the Netherlands with unprecedented spatiotemporal resolution. We find small plasma structures—which we call ‘needles’—that are the dominant source of radio emission from the positive leaders. These structures appear to drain charge from the leader, and are probably the reason why positive leaders disconnect from negative ones, and why cloud-to-ground lightning connects to the ground multiple times.
Subject code	290
Language	English
Publishing country	de
Document type	Article ; Online
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