Spectroscopy and imaging of newly discovered planetary nebulae (original) (raw)

Optical observations of planetary nebula candidates from the northern hemisphere

Astronomy and Astrophysics Supplement Series, 1996

We present Hα+[N ii] images of 17 and low resolution spectra of 14 IRAS-selected planetary nebula candidates. The Hα+[N ii] images are presented as finding charts. Contour plots are shown for the resolved planetary nebulae. From these images accurate optical positions and mean optical angular diameters were determined. Optical spectra show that the IRAS-selected and radio detected planetary nebula candidates are indeed planetary nebulae. Three planetary nebula candidates, previously not detected in the radio continuum were seen in Hα. They are larger, low surface brightness planetary nebulae. Most of these IRAS planetary nebulae are heavily extinct, having an average AV of 7 magnitudes. About half of the planetary nebulae seem to be of low excitation, having central stars with an effective temperature probably ∼ 60.000 K or less.

Discovery of New Faint Northern Galactic Planetary Nebulae

Revista mexicana de astronomía y astrofísica

We present the discovery of 6 nebular objects made by amateur astronomers. Four of these discoveries are clearly planetary nebulae (PNe), one is a possible PN, and another is a likely H II region. The bipolar nebula Ou4 presents the largest angular extent ever found : over one degree on the sky! We consider various scenarios that could explain such a nebula. Ou4 could be one of the nearest PNe known, though its possible PN nature will need confirmation.

Planetary Nebulae: Observational Properties, Mimics and Diagnostics

Publications of the Astronomical Society of Australia, 2010

The total number of true, likely and possible planetary nebulae (PN) now known in the Milky Way is nearly 3000, double the number known a decade ago. The new discoveries are a legacy of the recent availability of wide field, narrowband imaging surveys, primarily in the light of H-alpha. In this paper, we summarise the various PN discovery techniques, and give an overview of the many types of objects which mimic PN and which appear as contaminants in both Galactic and extragalactic samples. Much improved discrimination of classical PN from their mimics is now possible based on the wide variety of high-quality multiwavelength data sets that are now available. We offer improved taxonomic and observational definitions for the PN phenomenon based on evaluation of these better diagnostic capabilities. However, we note that evidence is increasing that the PN phenomenon is heterogeneous, and PN are likely to be formed from multiple evolutionary scenarios. In particular, the relationships between some collimated symbiotic outflows and bipolar PN remain uncertain.

Planetary nebulae and how to find them: A concise review

Frontiers in Astronomy and Space Sciences

This review provides useful background and information on how we find, vet and compile Planetary Nebulae (PNe) candidates and verify them. It presents a summary of the known Galactic PNe population and their curation in the Hong Kong/AAO/Strasbourg/Hα PNe catalogue, “HASH”. It is a simple introduction for anyone interested in working with PNe, including postgraduate students entering the field and for more general interest too.

Optical observations of southern planetary nebula candidates

Astronomy and Astrophysics Supplement Series, 1996

We present Hα+[N ii] images and low resolution spectra of 16 IRAS-selected, southern planetary nebula candidates previously detected in the radio continuum. The Hα+[N ii] images are presented as finding charts. Contour plots are shown for the resolved planetary nebulae. From these images mean optical angular diameters were determined. Optical spectra show that these IRAS-selected and radio detected planetary nebula candidates are indeed planetary nebulae. The values for their extinction coefficient is generally very high. More than half of the planetary nebulae seem to be of low excitation, having central stars with an effective temperature of probably ∼ 60 000 K or less.

Central stars of planetary nebulae: New spectral classifications and catalogue

Astronomy & Astrophysics, 2011

Context. There are more than 3000 true and probable known Galactic Planetary Nebulae (PNe), but only for 13% of them there is central star spectroscopic information available. Aims. To contribute to the knowledge of central stars of planetary nebulae and star evolution. Methods. We undertook a spectroscopic survey of central stars of PNe in low resolution and compiled a large list of central stars for which information was dispersed in the literature. Results. We complete a catalogue of 492 true and probable CSPN and we provide a preliminary spectral classification for 45 central star of PNe, This made it possible to update the proportion of CSPN with atmosphere poor in hydrogen with regard to the whole in at least 30% and contribute with statistical information that allow to infer the origin of H-poor stars.

The morphological and structural classification of planetary nebulae

… Planetary Nebulae II …, 2000

We present a statistical analysis of a complete sample (255) of northern planetary nebulae (PNe). Our analysis is based on morphology as a main parameter. The major morphological classes are: round (26% of the sample), elliptical (61 %), and bipolar (13 %) PNe. About a half of the round and 30 % of the elliptical PNe present multiple shells. Round PNe have higher galactic latitude (|b| =12) and galactic height (< z >=753 pc), than the elliptical (|b| = 7, < z >=308 pc) and bipolar (|b| = 3, < z >=179 pc). This possibly implies a different progenitor mass range across morphology, as a different stellar population would suggest.

2009

Context. We have carried out a semi-automated search for planetary nebulae (PNe) in the INT photometric H-alpha survey (IPHAS) catalogue. We present the PN search and the list of selected candidates. We cross correlate the selected candidates with a number of existing infrared galactic surveys in order to gain further insight into the nature of the candidates. Spectroscopy of a subset of objects is used to estimate the number of PNe present in the entire candidate list. Aims. The overall aim of the IPHAS PN project is to carry out a deep census of PNe in the northern Galactic plane, an area where PN detections are clearly lacking. Methods. The PN search is carried out on the IPHAS photometric catalogue. The candidate selection is based on the IPHAS and 2MASS/UKIDSS colours of the objects and the final candidate selection is made visually. Results. From the original list of ∼600 million IPHAS detections we have selected a total of 1005 objects. Of these, 224 are known objects, leavin...

Planetary nebulae near the Galactic center: Identifications

Astronomy and Astrophysics, 2004

We surveyed the central 4 x 4 degrees of the Galactic center for planetary nebulae in the light of [S III] λ9532 and found 94 PNe that were not previously known, plus 3 that were previously identified as possible candidates. For 63 of these 97 objects, we obtained spectra that are consistent with highly reddened PN while the other 34 could not be recovered spectroscopically and remain unverified. Of the 94 candidates, 54 and 57 were detected via radio at 3 and 6 cm, respectively. An additional 20 PNe candidates were found during follow-up Hα imaging but have not yet been verified spectroscopically. Based on the properties of IRAS sources in this region of the Galaxy, and on the total luminosity of the Galactic bulge, the expected number of PNe is ∼ 250, only 50% more than the 160 PNe candidates now known. Thus, surveys for PNe in the bulge are approximately two-thirds complete with the remainder likely hidden behind dust.

Planetary nebulae discovered and confirmed by amateur astronomers

2018

Unreferenced objects from the sky are regularly discovered by amateur astronomers from their own images or from professional images. Following the example of the Deep Sky Hunter list (DSH), thanks to the initiative of Agnès Acker and Pascal Le Dû [1][5], a list of planetary nebulae (PN) candidates is maintained in France and regularly published in the Société Astronomique de France (SAF) journal (L’Astronomie) and then in VizieR at the Strasbourg Astronomical Data Center (CDS). Recently, amateur astronomers specialising in spectroscopy have managed to observe the spectra of some of these candidates to confirm their nature.

Spectroscopy and imaging of newly discovered planetary nebulae (original) (raw)

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