On H II Regions and Pulsar Distances*

Prentice, A. J. R.; Haar, D. Ter

doi:10.1093/mnras/146.4.423

Cited by 75 publications

(17 citation statements)

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“…This was first discussed by Mitra et al (2003), following earlier work on the effect of HII regions and OB stars on the dispersion measure (DM) of PSR by Prentice & Ter Haar (1969), Grewing & Walmsley (1971), and in an earlier paper by Mitra & Ramachandran (2001). Several discussions of such observed or suspected RM anomalies can be found in the literature (see e.g., Rand & Kulkarni 1989;Han et al 1999;Brown & Taylor 2001).…”

Section: The Reliability Of the Rm Estimatesmentioning

confidence: 91%

The large-scale magnetic field in the fourth Galactic quadrant

Nota¹,

Katgert²

2010

A&A

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Aims. We have re-examined the published rotation measures (RMs) of extragalactic point sources and pulsars with |b| < 3 • to study the magnetic field in the fourth Galactic quadrant. Methods. We reduced the influence of structure in electron density as much as possible by excluding objects for which Hα-data indicate large fluctuations in n e somewhere along the line of sight. We also excluded objects for which the RM may have been significantly "corrupted" by an intervening supernova remnant. We modeled RM(l), the longitude dependence of RM of the unaffected extragalactic sources and pulsars. We assumed several geometries for the large-scale field. All but one of those are based on logarithmic spiral arms (with various pitch angles and widths), while one has circular symmetry. We also made different assumptions about the large-scale n e -distribution. Results. The data suggest the following generic behaviour of the large-scale field in the 4th Galactic quadrant. The field is most likely organized along logarithmic spiral arms and shows two significant reversals: from the Norma arm (CCW field) to the Norma-Crux interarm region (CW field), and from the Norma-Crux interarm region to the Crux arm (CCW field). The present data do not constrain the field in and beyond the Crux-Carina interarm region. Although the models give a good description of the global character of RM(l), individual RM-estimates deviate by typically 15 times their measurement errors. We argue that these large deviations are most likely due to the "small-scale" field that dominates on scales of up to several hundred pc. Conclusions. The picture that emerges is thus of a field that has significant structure on smaller scales, but for which the average values in arms and interarm regions are nevertheless well-defined. In addition, this smaller-amplitude large-scale field appears to reverse at each arm-interarm boundary that we can study with the present data. We briefly discuss the link between these results and theoretical predictions.

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Section: The Reliability Of the Rm Estimatesmentioning

confidence: 91%

The large-scale magnetic field in the fourth Galactic quadrant

Nota¹,

Katgert²

2010

A&A

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“…The pulsar velocity would be about 930 km s −1 at such a distance, which is at the extreme end of the pulsar velocity range. The computed value of R is also much larger than the value estimated by Prentice & ter Haar (1969) which gives 160 pc and the value 2900 pc given by Taylor et al (1993), so that the model of a uniformly distributed medium is unlikely.…”

Section: Discussionmentioning

confidence: 54%

The interstellar turbulent plasma spectrum in the direction to PSR B1642-03 from multi-frequency observations of interstellar scintillation

Smirnova

Shishov

Sieber³

et al. 2006

A&A

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Multi-frequency observations of interstellar scintillation toward the pulsar PSR B1642-03 were analyzed to estimate the spectrum of interstellar plasma inhomogeneities in the direction of this pulsar. Using data over the frequency range from 103 MHz to 5 GHz, we constructed the composite structure function (SF) of phase fluctuations, which covers a corresponding wide range of turbulence scales. The structure function shows that the interstellar plasma spectrum in the direction to this pulsar follows a piecewise power law. The power law is well described by two exponents: n = 3.7 for scales from 10 9 to 10 15 cm (Kolmogorov spectrum) and n = 3.35 for scales less than 10 9 cm. We interpret the unusual behaviour of the spectrum to be caused by the line of sight passing through the North Polar Spur, which may have plasma properties similar to the anisotropic plasma of the solar wind, although at a very different density.

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“…Parameters of the Regions Shown inFigure IV-4 nebula entirely, the distance to the pulsar must be 15.9 kpc, which is beyond A'.This distance is based on a path length through a two-phase medium for which the dispersion measure increases 30.17 pc cm for each kpc of path length.The distance of 15.9 kpc is also considerably larger than that derived for other pulsars, particularly those for which their lines of sight encounter H II regions(Terzian, 1972;Prentice and ter Haar, 1969).Although it is possible that the line of sight encounters neither nebula, it seems more likely that it passes through part of one since, otherwise, the pulsar would lie beyond the solar orbit.Hence, a distance of 2.6 kpc to 1858+03 appears most reasonable.…”

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confidence: 73%

Radio spectral line studies of the interstellar medium in the galactic plane / by Andrew Wilkin Seacord, II.

Seacord¹

1975

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On H II Regions and Pulsar Distances*

Cited by 75 publications

References 0 publications

The large-scale magnetic field in the fourth Galactic quadrant

The large-scale magnetic field in the fourth Galactic quadrant

The interstellar turbulent plasma spectrum in the direction to PSR B1642-03 from multi-frequency observations of interstellar scintillation

Radio spectral line studies of the interstellar medium in the galactic plane / by Andrew Wilkin Seacord, II.

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