Millimeter observations of planetary nebulae

Umana, G.; Leto, P.; Trigilio, C.; Buemi, C. S.; Manzitto, P.; Toscano, S.; Dolei, S.; Cerrigone, L.

doi:10.1051/0004-6361:20078796

Cited by 12 publications

(14 citation statements)

References 21 publications

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“…Yet in our data the effect is not observed. This conclusion is in agreement with new observations of planetary nebulae at 43 GHz (Umana et al 2008), whose measurements are mostly in agreement within errors with those presented in this paper (with exception for PN IC2165 (221.3-12.3)).…”

Section: Analysis Of Flux Density Resultssupporting

confidence: 93%

Survey of planetary nebulae at 30 GHz with OCRA-p

Pazderska¹,

Gawroński²,

Feiler³

et al. 2009

A&A

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Aims. We report the results of a survey of 442 planetary nebulae at 30 GHz. The purpose of the survey is to develop a list of planetary nebulae as calibration sources that could be used for high frequency calibration in future. For 41 PNe with sufficient data, we test the emission mechanisms in order to evaluate whether or not spinning dust plays an important role in their spectra at 30 GHz. Methods. The 30-GHz data were obtained with a twin-beam differencing radiometer, OCRA-p, which is in operation on the Toruń 32-m telescope. Sources were scanned both in right ascension and declination. We estimated flux densities at 30 GHz using a free-free emission model and compared it with our data. Results. The primary result is a catalogue containing the flux densities of 93 planetary nebulae at 30 GHz. Sources with sufficient data were compared with a spectral model of free-free emission. The model shows that free-free emission can generally explain the observed flux densities at 30 GHz thus no other emission mechanism is needed to account for the high-frequency spectra.

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Section: Analysis Of Flux Density Resultssupporting

confidence: 93%

Survey of planetary nebulae at 30 GHz with OCRA-p

Pazderska¹,

Gawroński²,

Feiler³

et al. 2009

A&A

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“…Sieber et al (1981) are shown by squares. The other flux densities shown were reported at 330 MHz (Rengelink et al 1997), 1420 MHz (Condon et al 1998;Pineault et al 1993), 4.85 GHz (Becker et al 1991), 30 GHz (Pazderska et al 2009), and 43 GHz (Umana et al 2008) and shown by open circles. The new λ6 cm and λ11 cm measurements are marked as filled circles.…”

Section: Discussionmentioning

confidence: 69%

Newλ6 cm andλ11 cm observations of the supernova remnant CTA 1

Sun

Reich

Wang

et al. 2011

A&A

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Aims. We attempt to study spatial variations in the spectrum and rotation measures (RMs) of the large-diameter, high-latitude supernova remnant (SNR) CTA 1. Methods. We conducted new λ6 cm and λ11 cm observations of CTA 1 using the Urumqi 25-m and Effelsberg 100-m telescopes. Data at other wavelengths were included to investigate the spectrum and polarisation properties. Results. We obtained new total intensity and polarisation maps at λ6 cm and λ11 cm with angular resolutions of 9. 5 and 4. 4, respectively. We derived a spectral index of α = −0.63 ± 0.05 (S ν ∝ ν α ) based on the integrated flux densities at 408 MHz, 1420 MHz, 2639 MHz, and 4800 MHz. The spectral index map calculated from data at the four frequencies shows a clear steepening of the spectrum from the strong shell emission towards the north-western breakout region with weak diffuse emission. The decrease of the spectral index is up to about Δα = 0.3. The RM map derived from polarisation data at λ6 cm and λ11 cm shows a sharp transition between positive RMs in the north-eastern and negative RMs in the south-western part of the SNR. We note a corresponding RM pattern of extragalactic sources and propose the existence of a large-diameter Faraday screen in front of CTA 1, which covers the north-eastern part of the SNR. The RM of the Faraday screen is estimated to be about +45 rad m −2 . A RM structure function of CTA 1 indicates a very regular magnetic field within the Faraday screen, which is stronger than about 2.7 μG for a distance of 500 pc. Conclusions. CTA 1 is a large-diameter shell-type SNR located out of the Galactic plane, which makes it an ideal object to study its properties without suffering confusion. The previous detection of the rare breakout phenomenon in CTA 1 is confirmed. We identify a Faraday screen partly covering CTA 1 with a regular magnetic field in the opposite direction to the interstellar magnetic field. The detection of Faraday screens in the Galactic plane is quite common, but is difficult at high latitudes where the polarisation angles of weak polarised background emission are rotated. Additional RMs from extragalactic sources are needed for this purpose, although the number density of the extragalactic RMs that have been measured remains small despite significant observational progress.

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“…In a previous paper (Umana et al 2008a), we published the flux density measurements of planetary nebulae (PNe).…”

Section: Introductionmentioning

confidence: 99%

7 mm continuum observations of ultra compact HII regions

Leto

Umana²,

Trigilio³

et al. 2009

A&A

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Aims. Ultra compact HII (UCHII) regions are indicators of high-mass star formation sites and are distributed mainly in the Galactic plane. They exhibit a broad band spectrum with significant emission between near-IR and radio wavelengths. We intend to investigate the possible contribution of the forthcoming ESA Planck mission to the science of UCHII regions by evaluating the possibility of detecting UCHIIs that are bright in the radio regime. Methods. We performed new 7 mm observations of a sample of UCHII regions. The observations were designed to acquire highfrequency radio spectra. For each source in our sample, the free-free radio spectrum has been modeled. Along with far-IR measurements, our spectra allow us to estimate the flux densities of the sources in the millimeter and sub-millimeter bands. We extrapolated and summed the ionized-gas (free-free radio emission) and dust (thermal emission) contributions in the afore mentioned wavelength ranges. The possibility of Planck detecting the selected sources can be assessed by comparing the estimated flux densities to the expected sensitivity in each Planck channel. To obtain a realistic estimation of the noise produced by the Galactic emission, the Planck sky model software package was used. Results. For each target source, from our new 7 mm data and other radio measurements from the literature, important physical parameters such as electron density and their spatial distribution, source geometry and emission measure were derived. We conclude that, in the case of the present sample, located close to the Galactic center, Planck will have a very low detection rate. In contrast, assuming that our sample is representative of the whole UCHII-region population, we derive a very high probability of detecting this kind of source with Planck if located instead close to the anticenter. From the analysis of the ionized-gas properties, we suggest that the selected sample could also be contaminated by other kinds of Galactic objects.

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Millimeter observations of planetary nebulae

Cited by 12 publications

References 21 publications

Survey of planetary nebulae at 30 GHz with OCRA-p

Survey of planetary nebulae at 30 GHz with OCRA-p

Newλ6 cm andλ11 cm observations of the supernova remnant CTA 1

7 mm continuum observations of ultra compact HII regions

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