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Related papers: Parsec-scale magnetic fields in Arp 220

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(Edited for length) The Zeeman effect is the only observational technique available to measure directly the strength of magnetic fields in regions of star formation. We review the physics of the Zeeman effect and its practical use in both…

Astrophysics of Galaxies · Physics 2019-11-15 Richard M. Crutcher , Athol J. Kemball

From targeted observations of ground-state OH masers towards 702 Multibeam (MMB) survey 6.7-GHz methanol masers, between Galactic longitudes 186$^{\circ}$ through the Galactic centre to 20$^{\circ}$, made as part of the `MAGMO' project, we…

Astrophysics of Galaxies · Physics 2020-01-29 C. S. Ogbodo , J. A. Green , J. R. Dawson , S. L. Breen , S. A. Mao , N. M. McClure-Griffiths , T. Robishaw , L. Harvey-Smith , .

Measuring interstellar magnetic fields is extremely important for understanding their role in different evolutionary stages of interstellar clouds and of star formation. However, detecting the weak field is observationally challenging. We…

Astrophysics of Galaxies · Physics 2021-01-06 Atanu Koley , Nirupam Roy , Karl M. Menten , Arshia M. Jacob , Thushara G. S. Pillai , Michael R. Rugel

Arp 220 is the prototypical Ultraluminous Infrared Galaxy (ULIRG), and one of the brightest objects in the extragalactic far-infrared sky. It is the result of a merger between two gas rich spiral galaxies which has triggered starbursting…

Astrophysics of Galaxies · Physics 2024-12-20 David L Clements , Qizhou Zhang , K. Pattle , G. Petitpas , Y. Ding , J. Cairns

Magnetic fields have been observed on all scales in our Galaxy, from AU to kpc. With pulsar dispersion measures and rotation measures, we can directly measure the magnetic fields in a very large region of the Galactic disk. The results show…

Astrophysics · Physics 2009-01-01 Jinlin Han

The southern maser site OH 300.969+1.147 has been studied using the Long Baseline Array of the Australia Telescope National Facility. The 1665- and 1667-MHz hydroxyl ground-state transitions were observed simultaneously. A series of maps…

Astrophysics of Galaxies · Physics 2015-05-13 J. L. Caswell , B. Hutawarakorn Kramer , J. E. Reynolds

IRAS20126+4104 is a well studied B0.5 protostar that is surrounded by a ~1000 au Keplerian disk and is where a large-scale outflow originates. Both 6.7-GHz CH3OH masers and 22-GHz H2O masers have been detected toward this young stellar…

Solar and Stellar Astrophysics · Physics 2014-03-05 G. Surcis , W. H. T. Vlemmings , H. J. van Langevelde , L. Moscadelli , B. Hutawarakorn Kramer

Our analysis of a VLBA 12-hour synthesis observations of the OH masers in W49N has provided detailed high angular-resolution images of the maser sources, at 1612, 1665 and 1667 MHz. The images, of several dozens of spots, reveal anisotropic…

Astrophysics of Galaxies · Physics 2015-06-04 Avinash A. Deshpande , W. M. Goss , J. E. Mendoza-Torres

Through polarization observations, circumstellar masers are excellent probes of the magnetic field in the envelopes of late-type stars. Whereas observations of the polarization of the SiO masers close to the star and on the OH masers much…

Astrophysics · Physics 2009-11-10 W. H. T. Vlemmings , H. J. van Langevelde , P. J. Diamond

Full-polarization MERLIN and VLBA observations of the 1720-MHz maser emission from the OH molecule in the supernova remnant W44 are presented. Zeeman splitting has been directly resolved between right- and left-circularly polarized spectra…

Astrophysics · Physics 2009-11-10 Ian M. Hoffman , W. M. Goss , C. L. Brogan , M. J. Claussen

We present global VLBI observations of the first-excited state OH masers in the massive star-forming region Onsala 1 (ON 1). The 29 masers detected are nearly all from the 6035 MHz transition, and nearly all are identifiable as Zeeman pair…

Astrophysics of Galaxies · Physics 2010-04-23 Vincent L. Fish , Loránt O. Sjouwerman

Several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties.…

Solar and Stellar Astrophysics · Physics 2015-11-02 S. P. Järvinen , T. A. Carroll , S. Hubrig , M. Schöller , I. Ilyin , H. Korhonen , M. Pogodin , N. A. Drake

Using the Very Long Baseline Array (VLBA) we performed a high resolution OH maser survey in Galactic star-forming regions (SFRs). We observed all the ground state spectral lines: the main lines at 1665 and 1667 MHz and the satellite lines…

Solar and Stellar Astrophysics · Physics 2016-03-28 A. E. Ruiz-Velasco , D. Felli , V. Migenes , B. K. Wiggins

For the first time we study the Eastern nucleus in greater detail and search for the more extended emission in the molecular gas in different CO line transitions of the famous ULIRG Arp 220. Furthermore we present a model of the merger in…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 S. König , M. García-Marín , A. Eckart , D. Downes , J. Scharwächter

We present estimates of magnetic field strengths in the interstellar media of starburst galaxies derived from measurements of Zeeman splitting associated with OH megamasers. The results for eight galaxies with Zeeman detections suggest that…

Astrophysics of Galaxies · Physics 2015-06-17 James McBride , Eliot Quataert , Carl Heiles , Amber Bauermeister

The scintillation of pulsars reveals small-scale structure of the interstellar medium. A powerful technique for characterizing the scintillating structures (screens) combines analysis of scintillation arcs and very long baseline…

High Energy Astrophysical Phenomena · Physics 2025-10-21 Ashley M. Stock , Fardin Syed , Marten H. van Kerkwijk , Rebecca Lin , Franz Kirsten , Ue-Li Pen

We present a joint analysis of HI absorption Zeeman measurements and the morphology of filamentary HI emission to investigate the three-dimensional structure of the magnetic field in the diffuse neutral interstellar medium (ISM). Our…

Astrophysics of Galaxies · Physics 2025-08-28 Marta Nowotka , Susan E. Clark , Blakesley Burkhart , Laura Fissel , Tao-Chung Ching , Timothy Robishaw , Carl Heiles

Recent observations of the accretion disk around the Herbig Ae/Be star HD169142 revealed its complex and asymmetric morphology indicating the presence of planets. The knowledge of the magnetic field structure in host stars is indispensable…

Solar and Stellar Astrophysics · Physics 2025-04-08 S. Hubrig , S. P. Jarvinen , I. Ilyin , M. Schöller

The spatially resolved broad-band spectroscopy with Very Long Baseline Interferometry (VLBI) is one of the few methods that can probe the physical conditions inside blazar jets. We report on measurements of the magnetic field strength in…

Astrophysics of Galaxies · Physics 2010-01-19 K. V. Sokolovsky , Y. Y. Kovalev , A. P. Lobanov , T. Savolainen , A. B. Pushkarev , M. Kadler

Radio observations of gas in the Milky Way and Local Group are vital for understanding how galaxies function as systems. The unique sensitivity of Arecibo's 305m dish, coupled with the 7-beam Arecibo L-Band Feed Array (ALFA), provides an…