A database of circumstellar OH masers

Engels, D.; Bunzel, Felix

doi:10.1017/s1743921307013208

Cited by 5 publications

(5 citation statements)

References 17 publications

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“…The ground-state OH maser lines at 1612, 1665 and 1667 MHz are frequently detected in late-type stars that show mass loss at high rates. A recent compilation by Engels & Bunzel (2008) gives 2297 circumstellar masers of which 1945 show the classical double-peak profile at 1612 MHz. The polarization information is not available or neglected in the interferometric surveys of the Galactic plane (Sevenster et al 1997a(Sevenster et al , 1997b(Sevenster et al , 2001 in numerous single-dish studies of IRAS colour-selected objects (e.g.…”

Section: Introductionmentioning

confidence: 99%

Polarization properties of OH masers in AGB and post-AGB stars

Wolak

Szymczak

Gérard

2011

A&A

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Context. Ground-state OH maser emission from late-type stars is usually polarized and remains a powerful probe of the magnetic field structure in the outer regions of circumstellar envelopes if observed with high angular and spectral resolutions. Observations in all four Stokes parameters are quite sparse and this is the most thorough, systematic study published to date. Aims. We aim to determine polarization properties of OH masers in an extensive sample of stars that show copious mass loss and search for candidate objects that are well-suited for high angular resolution studies. Methods. Full-polarization observations of the OH 1612 and 1667 MHz maser transitions were carried out for a sample of 117 AGB and post-AGB stars. Several targets were also observed in the 1665 MHz line. Results. A complete set of full-polarization spectra together with the basic polarization parameters are presented. Polarized features occur in more than 75% of the sources in the complete sample and there is no intrinsic difference in the occurrence of polarized emission between the three classes of objects of different infrared characteristics. The highest fractional polarization occurs for the post-AGB+PN and the Mira+SR classes at 1612 and 1667 MHz, respectively. Differences in the fractional polarization between the sources at different evolutionary stages appear to be related to depolarization caused by blending. The alignment of the polarization angles at the extreme sides of the shell implies a regular structure of the magnetic field of a strength of 0.3-2.3 mG. Conclusions. Polarized OH maser features are widespread in AGB and post-AGB stars. The relationship between the circular and linear fractional polarizations for a representative sample are consistent with the standard models of polarization for the Zeeman splitting higher than the Doppler line width, whereas the polarized features are the σ components.

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Section: Introductionmentioning

confidence: 99%

Polarization properties of OH masers in AGB and post-AGB stars

Wolak

Szymczak

Gérard

2011

A&A

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“…With a sensitivity at least one order of magnitude better than previous spatially-limited surveys of OH masers (e.g. Sevenster et al 2001;Caswell and Haynes 1987), and taking into account the number of known OH maser sources to date (∼2300 in evolved stars, Engels et al 2010), we expect to find several thousand new OH maser sources (Figure 6). Such a sensitive and unbiased survey will allow us to make statistical studies of the processes in these evolutionary phases as well as proper comparisons with results of Galactic surveys at other wavelengths.…”

Section: Oh Masers In Young and Evolved Starsmentioning

confidence: 78%

“…As of 2010 July, the Engels et al (2010) database listed 344 known stellar OH masers at 1612 MHz within 3 • from the Galactic Center. A histogram of their flux densities is shown in Figure 7(a).…”

Section: Simulated Catalogue Of Oh Masers In Evolvedmentioning

confidence: 99%

GASKAP—The Galactic ASKAP Survey

Dickey

McClure-Griffiths

Gibson

et al. 2013

Publ. Astron. Soc. Aust.

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A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder * Hubble Fellow. telescope. The survey will study the distribution of H i emission and absorption with unprecedented angular and velocity resolution, as well as molecular line thermal emission, absorption, and maser lines. The area to be covered includes the Galactic plane (|b| < 10°) at all declinations south of δ = +40 • , spanning longitudes 167 • through 360 • to 79 • at b = 0 • , plus the entire area of the Magellanic Stream and Clouds, a total of 13 020 deg 2 . The brightness temperature sensitivity will be very good, typically σ T 1 K at resolution 30 arcsec and 1 km s −1 . The survey has a wide spectrum of scientific goals, from studies of galaxy evolution to star formation, with particular contributions to understanding stellar wind kinematics, the thermal phases of the interstellar medium, the interaction between gas in the disk and halo, and the dynamical and thermal states of gas at various positions along the Magellanic Stream.

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“…The youth of IRAS 07027 as a PN is also evidenced by the detection of OH maser emission at 1612 MHz, which is usually observed in their precursors, the OH/IR stars, but rarely in PNe. The OH emission is being detected only coming from the blue side of the shell, as consequence of the ionized inner region being optically thick at 1612 MHz [13,14]. This is supported by the shifting velocity with respect to the CO emission, which is detected by expansion velocity which was moving at by 30.5 km/sec, which twice of expansion velocity given by [1,15].…”

Section: Iras 07027-7934mentioning

confidence: 89%

Ionization Structure of Heavy Metals for Planetary Nebulae

Goshu¹

2018

AJAA

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The purpose of this work to reproduces the flux of lines emitted by the ionized gas, resulting in a good agreement between observed and predicted line fluxes, temperatures and electron density with the chemical abundances of ionic species with carbon and oxygen rich planetary. The model has been calculated using clouds of dust grains in order to calculate the electron temperature, density, and emission fluxes. The dust grain with polycyclic aromatic hydrocarbons (PAH) physics combined with thick shell geometry solves the problem of the heating and allows the fitting of fluxes lines, the electron temperatures and the ionization structure of the nebula. Among other lines, we determined line ratio of CIIλ4267A, [NII] λ5755A, 6584A, 6548A, [SII] λ4078A, 4070A, 6716A, and 6731A and compared the results with the observation data by changing the abundances of C, N, O and S, which are enhanced by a factor of 2. The analysis of the ionization structure of the gas, as well as this calculation of the flux of ions, is presented in this work. Therefore, our result revealed that flux lines like [NII] λ6584A, [OII] λ3727A+29A and [OIII] λ5007A greater than the observed fluxes. The nebulae are found to have low electron temperature than found by the previous author, but the electron density is high.

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A database of circumstellar OH masers

Cited by 5 publications

References 17 publications

Polarization properties of OH masers in AGB and post-AGB stars

Polarization properties of OH masers in AGB and post-AGB stars

GASKAP—The Galactic ASKAP Survey

Ionization Structure of Heavy Metals for Planetary Nebulae

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