Papers by Quentin A Parker
Monthly Notices of the Royal Astronomical Society, 2018
A combination of archival multi-frequency radio observations with narrow-band Hα optical imagery ... more A combination of archival multi-frequency radio observations with narrow-band Hα optical imagery and new confirmatory optical spectroscopy have shown that candidate supernova remnant G6.31+0.54 can now be confirmed as part of a Galactic supernova remnant (SNR). It has non-thermal emission, an optical emission line spectrum displaying shock excitation and standard SNR line ratios, fine filamentary structures in Hα typical of optical remnants and closely overlapping radio and optical footprints. An X-ray ROSAT source 1RXS J175752.1-231105 was also found that matches the radio and optical emission though a definite association is not proven. Nevertheless, taken together, all these observed properties point to a clear SNR identification for this source. We provide a rough estimate for the kinematic distance to G6.31+0.54 of �?�4.5 kpc. The detected optical filaments are some �?� 10 arcminutes in extent (or about 13 pc at the assumed distance). However, as only a partial arcuate structure of the SNR can be seen (and not a full shell) the full angular extent of the SNR is unclear. Hence the physical extent of the observed partial shell is also difficult to estimate. If we assume an approximately circular shell then a conservative fit to the optical arc shaped filaments gives an angular diameter of �?�20 arcminutes corresponding to a physical diameter of �?�26pc that shows this to be an evolved remnant.
AIP Conference Proceedings, 2005
The Macquarie/AAO/Strasbourg Hα Planetary Nebula Catalogue (MASH) of nearly 1000 new Galactic Pla... more The Macquarie/AAO/Strasbourg Hα Planetary Nebula Catalogue (MASH) of nearly 1000 new Galactic Planetary Nebulae (PNe) discovered from the AAO/UKST Hα survey of the southern Galactic plane is now essentially complete. The survey's excellent combination of resolution, uniformity, areal coverage and depth has enabled detection of this unprecedented new PN sample. MASH PNe are typically more evolved, obscured, of larger angular extent, and of lower surface brightness than those in most previous surveys. The number of PNe in the Galactic bulge has also been doubled. Though most of these are quite compact, more evolved examples have been found. The MASH catalogue represents a seven year programme of discovery and spectroscopic confirmation and will form the basis for significant studies. A key strength is that the whole sample has been obtained from the same, uniform survey data. The 75% increase in known Galactic PNe represents the largest single increase in such discoveries. MASH PNe will have a significant impact on many aspects of PNe research, especially for studies at the extremes of the luminosity function which were previously poorly represented.
Monthly Notices of the Royal Astronomical Society, 2012
We demonstrate a newly developed mid-infrared (MIR) planetary nebula (PN) selection technique. It... more We demonstrate a newly developed mid-infrared (MIR) planetary nebula (PN) selection technique. It is designed to enable efficient searches for obscured, previously unknown, PN candidates present in the photometric source catalogues of Galactic plane MIR sky surveys. Such selection is now possible via new, sensitive, high-to-medium resolution, MIR satellite surveys such as those from the Spitzer Space Telescope and the all-sky Wide-field Infrared Survey Explorer satellite missions. MIR selection is based on how different colour-colour planes isolate zones (sometimes overlapping) that are predominately occupied by different astrophysical object types. These techniques depend on the reliability of the available MIR source photometry. In this pilot study, we concentrate on MIR point-source detections and show that it is dangerous to take the MIR GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) photometry from Spitzer for each candidate at face value without examining the actual MIR image data. About half of our selected sources are spurious detections due to the applied source detection algorithms being affected by complex MIR backgrounds and the deblending of diffraction spikes around bright MIR point sources into point sources themselves. Nevertheless, once this additional visual diagnostic checking is performed, valuable MIR-selected PN candidates are uncovered. Four turned out to have faint, compact, optical counterparts in our Hα survey data missed in previous optical searches. We confirm all of these as true PNe via our follow-up optical spectroscopy. This lends weight to the veracity of our MIR technique. It demonstrates sufficient robustness that high-confidence samples of new Galactic PN candidates can be extracted from these MIR surveys without confirmatory optical spectroscopy and imaging. This is problematic or impossible when the extinction is large.
Proceedings of the International Astronomical Union, 2011
We have found the central star of Abell 70 (PN G038.1–25.4, hereafter A 70) to be a binary consis... more We have found the central star of Abell 70 (PN G038.1–25.4, hereafter A 70) to be a binary consisting of a G8 IV-V secondary and a hot white dwarf. The secondary shows enhanced Ba II and Sr II features, firmly classifying it as a barium star. The nebula is found to have Type-I chemical abundances with helium and nitrogen enrichment, which combined with future abundance studies of the central star, will establish A 70 as a unique laboratory for studying s-process AGB nucleosynthesis.
Monthly Notices of the Royal Astronomical Society, 2000
We have carried out a spectroscopic survey of 750 sources that are strong 25-mm emitters from the... more We have carried out a spectroscopic survey of 750 sources that are strong 25-mm emitters from the IRAS Faint Source data base. Many of these sources are previously unknown active galactic nuclei including new IRAS quasars, three of which we describe here: F2138222659, Z0636726845 and Z0555825008. They are all radio and X-ray quiet, and compared to the known IRAS quasars they have similar 25-mm luminosities, L(25 mm), but lower values of L25 mmaLB. Their F25 mmaF60 mm IRAS colours lie in the range 0.33 to 1.08, indicating the presence of relatively warm dust, presumably in a dusty torus surrounding the central source, and with temperatures similar to those of the known IRAS quasars. The quasar with the warmest dust, F2138222659, exhibits broad (full width at half-maximum ,4000 km s 21) asymmetric Balmer lines with Hg having an opposite asymmetry to the other broad lines; also Hb (only) is double-peaked. Fe ii is very weak in F2138222659 but strong in the other two quasars, and the anticorrelation between Fe ii and [O iii] holds as anticipated. Two of the quasars are unpolarized: although F2138222659 is optically polarized (2.1 per cent at 4950 A Ê), we argue that this provides little insight into the orientation of its dust torus relative to the line of sight.
Proceedings of the International Astronomical Union, 2006
About 500 MASH(Macquarie/AAO/Strasbourg Hα planetary nebula project) PNe were discovered towards ... more About 500 MASH(Macquarie/AAO/Strasbourg Hα planetary nebula project) PNe were discovered towards the galactic bulge (Parker et al. 2006). For 405 MASH PNe with a diameter < 35 arcsec, we obtain surface brightness, diameter and dynamical age of the nebulae. From line intensity ratios of 133 GBPN observed with the 6dF device, we obtain their density and ionized mass, and their central star temperatures. We discover 15 bipolar and/or nitrogen-rich GBPNe having probably massive stellar progenitors (Peyaud, 2005).
A survey for low surface brightness galaxies in Virgo using Tech Pan films
Not Availabl
New Images from the UKST Halpha Survey
A new method to estimate the Galactic extinction for the analysis of large scale structure in the Galactic center region
ABSTRACT
Astronomy from Wide-Field Imaging, 1994
extended red sensitivity. It has been produced under this name since about 1980 (Kodak P-255, 198... more extended red sensitivity. It has been produced under this name since about 1980 (Kodak P-255, 1981) and is available on Kodak's Estar base in a number of thicknesses and sizes. The thick **base Tech Pan is designated 4415 and has been used with great success by the amateur astronomical community for many years (e.g. Marty s 1991). Its astronomical potential was recognised early by Everhart (1981). However, tests at professional telescopes (e.g. West et al. 1981) and early sensitometer tests at the UK Schmidt Telescope (UKST) in 1981 and 1987 were discontinued when the glass and film samples did not respond well to normal hypersensitisation techniques. These and other difficulties led to a lack of interest among the professional astronomical community until quite recently (Russell et al. 1992; Parker & Malin 1992). The first successful use of 14 χ 14 inch hypered Tech-Pan 4415 film in the UKST was in March 1991. Films were obtained which exhibited excellent image quality and resolution. Furthermore, in good seeing these appeared to be about 1 magnitude deeper than the equivalent nia-F emulsion on glass but with considerably lower grain noise. This result was achieved because two main problems associated with Tech-Pan and film use in the UKST have been resolved. These were: 1) obtaining Tech-Pan film with long exposure speed sufficient for deep astronomical photography (i.e. reduction of low intenstiy reciprocity failure); 2) overcoming the practical difficulties of mounting large-format flexible film at the UKST's curved focal surface. Fuller details of how this was achieved are given in Parker (1992) and Parker, Malin & Russell (in preparation). Tech-Pan now accounts for more than 60% of all non-survey exposures on the telescope and over 250 film exposures have been taken since January 1992, amounting to about 20% of all current UKST exposures. An exciting variety of different astronomical projects which take full advantage of the superb imaging, low noise and fainter limits offered by Tech-Pan are underway. Here we present some quantitative results from COSMOS measuring machine scans of Tech-Pan film which clearly demonstrate the information gains over the traditional nia-F glass-based emulsion. These improvements lead directly to more effective and efficient use of the UKST and increased scientific productivity. Some of the areas in which Tech-Pan film can make a useful 129
Radio and optical studies of a complete sample of IRAS galaxies
Radio maps, spectra and CCD images have been obtained for almost all the 158 objects in a complet... more Radio maps, spectra and CCD images have been obtained for almost all the 158 objects in a complete sample of IRAS galaxies. The linear relation between radio and far-infrared luminosity is valid over the complete luminosity range (up to LIR=1.8×1012 L⊙, H○=75 km s�?�1 Mpc�?�1). The majority of the 10 most luminous galaxies show evidence of tidal disruption and have
Frontiers in Astronomy and Space Sciences
This review provides useful background and information on how we find, vet and compile Planetary ... more 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.
Galaxies
We present some preliminary findings on the population of planetary nebula where central stars (C... more We present some preliminary findings on the population of planetary nebula where central stars (CSPN) have been independently identified in the HASH catalogue. Many new discoveries and candidates have been found (416 at the time of this writing), adding significantly to the previously known sample of about 600. We also present results from a comparison between our own HASH measurements of CSPN and those provided in existing CSPN catalogues and those from Gaia. We show the value of a federated, multi-wavelength database of Galactic PNe like HASH in terms of not only uncovering faint, new CSPN but of assisting in correct identifications, removing PN mimics with apparent CSPN, correcting incorrect assignments and providing improved positions. HASH provides the community with a comprehensive and reliable resource for any study of the CSPN population of Galactic PNe.
The bright end of the radio PNe Luminosity Function
Recently, we (Filipovic et al. 2009) reported the first confirmed extragalactic radio-continuum d... more Recently, we (Filipovic et al. 2009) reported the first confirmed extragalactic radio-continuum detection of 15 PNe in the Magellanic Clouds (MCs). These new positive radio detections of MCs PNe open a door to the exciting possibility of construction of the radio Planetary Nebula Luminosity Function (PNLF) which would be of extreme help in understanding of properties of PNe in our
Galaxies, 2022
Planetary Nebulae (PNe) that are physical members of Galactic open clusters are powerful probes t... more Planetary Nebulae (PNe) that are physical members of Galactic open clusters are powerful probes that allow precise determination of their distance and crucially their initial mass on the main sequence. Here, we revisit the physical association of the PN BMP J1613–5406 with the open cluster NGC 6067 and present our preliminary results based on our new ESO/VLT FORS2 data. Our PN spectral data permit the calculation of a precise radial velocity and reddening to the PN that shows a tight consistency with the literature corresponding cluster parameters including importantly the radial velocity. Our measurements, combined with the agreement between the distances of the two objects and the fact that the PN is located well within the cluster boundaries, confirm that the PN is physically associated with the cluster. The cluster has a turn-off mass of around 5 solar masses that indicates a PN initial mass of around 5.6 solar masses. This is closer to the theoretical lower limit of core-collap...
We present new results of our wide-field redshift survey of galaxies in a 182 square degree regio... more We present new results of our wide-field redshift survey of galaxies in a 182 square degree region of the Shapley Supercluster (SSC) based on observations with the FLAIR-II spectrograph on the UK Schmidt Telescope. We present new measurements to give a total sample of redshifts for 710 bright (R<16.6) galaxies, of which 464 are members of the SSC (8000<v<18000 kms). Our data reveal that the main plane of the SSC extends further than previously realised, filling the whole extent of our survey region of 10 degrees by 20 degrees on the sky (35 Mpc by 70 Mpc). There is also a significant structure associated with the slightly nearer Abell 3571 cluster complex with a caustic structure evident out to a radius of 6 Mpc. These galaxies seem to link two previously identified sheets of galaxies and establish a connection with a third one at v=15000 kms. They also tend to fill the gap of galaxies between the foreground Hydra-Centaurus region and the more distant SSC. We calculate gala...
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Papers by Quentin A Parker