Considerable effort has been applied towards understanding the precise shaping mechanisms respons... more Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe). At least 10-20% of PNe have central stars (CSPN) with a close binary companion thought responsible for heavily shaping the ejected PN during common-envelope (CE) evolution, however morphological studies of the few available examples found no clear distinction between PNe and post-CE PNe. The discovery of several new binary central stars (CSPN) from the OGLE-III photometric variability survey has significantly increased the number of post-CE PNe available for morphological analysis to 30 PNe. High quality Gemini South narrow-band images are presented for most of the OGLE sample, while some previously known post-CE PNe are reanalysed with images from the literature. Nearly 30% of nebulae have canonical bipolar morphologies, however this could be as high as 60% once inclination effects are incorporated with the aid of geometric models. This is the strongest observational evidence yet linking CE evolution to bipolar morphologies. A higher than average proportion of the sample shows low-ionisation knots, filaments or jets suggesting they have a binary origin. These features are also common in nebulae around emission-line nuclei which may be explained by speculative binary formation scenarios for H-deficient CSPN. Based on observations made with Gemini South under programs GS-2008B-Q-65 and GS-2009A-Q-35.
We report infrared observations of the planetary nebula Hen 2-113 obtained with VLT/NACO, VLTI/MI... more We report infrared observations of the planetary nebula Hen 2-113 obtained with VLT/NACO, VLTI/MIDI, VLT/ISAAC and TIMMI at the ESO 3.6m. Hen 2-113 exhibits a clear ring-like structure superimposed to a more diffuse environment visible in the L' (3.8μm), M' (4.78μm) and 8.7μm bands. No clear core at 8.7μm and no fringes through the N band could be detected for this object with MIDI. A qualitative interpretation of the object structure is proposed using a diabolo-like geometrical model. Our ISAAC and TIMMI observations indicates that the PAHs are mostly concentrated towards the lobes of the diabolo and the bipolar lobes of the nebula. In L' band, a void 0.3" in diameter was discovered with NACO around the central source, which appears resolved with measured FWHM about 155 mas. Our measurements indicate that the observed fluxes from this source in L' and M' are about 300 and 800 times respectively smaller than those expected from a model including only the central star. This infrared excess can be explained by emission from a cocoon of hot dust (T˜1000K) with a total mass ˜10-9M⊙.
The table lists the heliocentric radial velocities for planetary nebulae in the direction of the ... more The table lists the heliocentric radial velocities for planetary nebulae in the direction of the Galactic bulge. The accuracy is about 2km/s. The measurements were made in June and July 1993, using the ESO CAT with spectral resolution of 30000-60000. Hα, [NII] 6548 and 6584 and [O III] 5007 were observed. (1 data file).
The radial velocity curve of FG Sge is established with 80 radial velocities measured from 1977 t... more The radial velocity curve of FG Sge is established with 80 radial velocities measured from 1977 to 1979 using the spectrophotometer CORAVEL. The mean period is 120 plus or minus 10 days, the mean amplitude and velocity being solar radii, 3.0 plus or minus 0.2 km/s and 37.5 plus or minus 0.1 km/s. The comparison with the simultaneous photometric variations shows that the luminosity variation happens nearly in phase with the radius variation. Using Wesselink's method, the value of the radius is estimated to about 140 solar radii, which leads to a pulsation mass of about 1 solar mass and a distance of about 2.5 Kpc. The mean broadening of the lines, deduced from the width of the correlation dip of FG Sge, would require a low rotation velocity.
We compare the populations of Red Giant stars and Planetary Nebulae in the Galactic Bulge, in the... more We compare the populations of Red Giant stars and Planetary Nebulae in the Galactic Bulge, in the light of recent determinations of their abundances patterns. We find both populations to be compatible. From the planetary nebulae, we find evidences that the Bulge did not form stars recently. The whole abundances pattern remains however puzzling, some elements favoring a quick evolution of the Galactic Bulge (Mg and Ti), and others a much slower one (He, O, Si, S, Ar and Ca).
A planetarium show highlighting the ALMA project is being jointly prepared by ESO and the Associa... more A planetarium show highlighting the ALMA project is being jointly prepared by ESO and the Association des Planétariums de Langue Française.
ABSTRACT We report discovery of ~500 planetary nebulae (PNe) in the central 200 sq.deg of the Gal... more ABSTRACT We report discovery of ~500 planetary nebulae (PNe) in the central 200 sq.deg of the Galactic Bulge from the AAO/UKST Halpha survey. Confirmatory UKST 6dF fibre spectroscopy and additional follow-up on 2-m class telescopes has led to a doubling of known Bulge PNe. This new population will have important implications for the bulge PN luminosity function and will provide improved determination of abundance gradients, a better picture of chemical evolution, as well as valuable test particles for dynamical studies.
... E. Lagadec, O. Chesneau, M. Matsuura, O. De Marco, JA de Freitas Pacheco, AA Zijlstra, A. Ack... more ... E. Lagadec, O. Chesneau, M. Matsuura, O. De Marco, JA de Freitas Pacheco, AA Zijlstra, A. Acker, GC Clayton. Abstract. We report infrared observations of the planetary nebula Hen 2‐113 obtained with VLT/NACO, VLTI/MIDI, VLT/ISAAC and TIMMI at the ESO 3.6m. Hen 2‐113 ...
The table lists the heliocentric radial velocities for planetary nebulae in the direction of the ... more The table lists the heliocentric radial velocities for planetary nebulae in the direction of the Galactic bulge. The accuracy is about 2km/s. The measurements were made in June and July 1993, using the ESO CAT with spectral resolution of 30000-60000. Halpha, [NII] 6548 and 6584 and [O III] 5007 were observed. (1 data file).
The exploitation of data from the Halpha southern survey and from the spectroscopic survey of new... more The exploitation of data from the Halpha southern survey and from the spectroscopic survey of newly discovered planetary nebulae (PN) is focussed on the 1500 PN of the galactic bulge, with the following objectives: -- history of expansion linked to the evolutive models as a function of progenitor mass; -- spatial distribution and kinematics to constrain the dynamics.
PN are excellent tracers for Galactic bulge dynamical studies because they are less affected by m... more PN are excellent tracers for Galactic bulge dynamical studies because they are less affected by metallicity bias than other tracers and have strong emission lines permitting accurate velocity determinations. Due to the relatively small numbers previously known throughout the Galaxy (i.e. ~1500) compared to those expected ~20000+) their potential as tracers of galactic structure and as windows to stellar evolution in the critical phase between PN and White Dwarf has only been partially realized. Furthermore, the number of bulge PN available for such studies has, until now, also been quite small (e.g. Zijlstra et al. 1997 and Beaulieu et al. 1999) so their potential as test particles of bulge dynamics and PN evolution also remains largely unrealised. We present our new PNe sample and an axisymmetrical model of the Bulge that we will be able to constrain.
Coordinates for 288 planetary nebulae searched for photometric variations in OGLE-III. Remarks ar... more Coordinates for 288 planetary nebulae searched for photometric variations in OGLE-III. Remarks are given according to the central star (CSPN) identification process detailed in the paper. For each planetary nebula the OGLE-III field, PN G designation, common name, equatorial coordinates and central star ID are given. (1 data file).
The Macquarie/AAO/Strasbourg Halpha Planetary Nebula Catalogue (MASH) contains 903 new true, like... more The Macquarie/AAO/Strasbourg Halpha Planetary Nebula Catalogue (MASH) contains 903 new true, likely and possible Galactic Planetary Nebulae (PNe) discovered from the AAO/UKST Halpha survey of the southern Galactic plane. The combination of depth, resolution, uniformity, and areal coverage of the H {alpha}survey has opened up an hitherto unexplored region of parameter space permitting the detection of this significant new PN sample. This catalogue includes also the spectra of the PNe as FITS files (in the "sp" subdirectory), and a gallery of images created as a combination of the Halpha and short red images of the survey. The second part, MASH-II (table mash2.dat) consists of over 300 true, likely and possible new Galactic PNe found after re-examination of the entire AAO/UKST Halpha survey of the Southern Galactic Plane in digital form. Over 240 of these new candidates were confirmed as bona fide PNe on the basis of spectroscopic observations. The spectra of this supplement...
Detection of close binary central stars with periods of less than a day is now well-tested and ro... more Detection of close binary central stars with periods of less than a day is now well-tested and routinely possible via photometric monitoring. For wide binary central stars with periods of weeks to years detection techniques are still in their infancy. Radial velocity monitoring programs are yet to be applied to very large samples and the method suffers from large systematic errors as well as intrinsic wind variability. One alternative we are exploring is the detection of dense circumstellar nebulae residing around a wide companion. The archetype of this class is EGB6 as revealed by HST imaging (Bond 2009). Here we present spectroscopic evidence for other EGB6-like central stars and discuss their relationship to symbiotic stars. A probable 12.5-day irradiated binary is also presented to demonstrate the limits of the photometric monitoring technique.
Considerable effort has been applied towards understanding the precise shaping mechanisms respons... more Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe). At least 10-20% of PNe have central stars (CSPN) with a close binary companion thought responsible for heavily shaping the ejected PN during common-envelope (CE) evolution, however morphological studies of the few available examples found no clear distinction between PNe and post-CE PNe. The discovery of several new binary central stars (CSPN) from the OGLE-III photometric variability survey has significantly increased the number of post-CE PNe available for morphological analysis to 30 PNe. High quality Gemini South narrow-band images are presented for most of the OGLE sample, while some previously known post-CE PNe are reanalysed with images from the literature. Nearly 30% of nebulae have canonical bipolar morphologies, however this could be as high as 60% once inclination effects are incorporated with the aid of geometric models. This is the strongest observational evidence yet linking CE evolution to bipolar morphologies. A higher than average proportion of the sample shows low-ionisation knots, filaments or jets suggesting they have a binary origin. These features are also common in nebulae around emission-line nuclei which may be explained by speculative binary formation scenarios for H-deficient CSPN. Based on observations made with Gemini South under programs GS-2008B-Q-65 and GS-2009A-Q-35.
We report infrared observations of the planetary nebula Hen 2-113 obtained with VLT/NACO, VLTI/MI... more We report infrared observations of the planetary nebula Hen 2-113 obtained with VLT/NACO, VLTI/MIDI, VLT/ISAAC and TIMMI at the ESO 3.6m. Hen 2-113 exhibits a clear ring-like structure superimposed to a more diffuse environment visible in the L' (3.8μm), M' (4.78μm) and 8.7μm bands. No clear core at 8.7μm and no fringes through the N band could be detected for this object with MIDI. A qualitative interpretation of the object structure is proposed using a diabolo-like geometrical model. Our ISAAC and TIMMI observations indicates that the PAHs are mostly concentrated towards the lobes of the diabolo and the bipolar lobes of the nebula. In L' band, a void 0.3" in diameter was discovered with NACO around the central source, which appears resolved with measured FWHM about 155 mas. Our measurements indicate that the observed fluxes from this source in L' and M' are about 300 and 800 times respectively smaller than those expected from a model including only the central star. This infrared excess can be explained by emission from a cocoon of hot dust (T˜1000K) with a total mass ˜10-9M⊙.
The table lists the heliocentric radial velocities for planetary nebulae in the direction of the ... more The table lists the heliocentric radial velocities for planetary nebulae in the direction of the Galactic bulge. The accuracy is about 2km/s. The measurements were made in June and July 1993, using the ESO CAT with spectral resolution of 30000-60000. Hα, [NII] 6548 and 6584 and [O III] 5007 were observed. (1 data file).
The radial velocity curve of FG Sge is established with 80 radial velocities measured from 1977 t... more The radial velocity curve of FG Sge is established with 80 radial velocities measured from 1977 to 1979 using the spectrophotometer CORAVEL. The mean period is 120 plus or minus 10 days, the mean amplitude and velocity being solar radii, 3.0 plus or minus 0.2 km/s and 37.5 plus or minus 0.1 km/s. The comparison with the simultaneous photometric variations shows that the luminosity variation happens nearly in phase with the radius variation. Using Wesselink's method, the value of the radius is estimated to about 140 solar radii, which leads to a pulsation mass of about 1 solar mass and a distance of about 2.5 Kpc. The mean broadening of the lines, deduced from the width of the correlation dip of FG Sge, would require a low rotation velocity.
We compare the populations of Red Giant stars and Planetary Nebulae in the Galactic Bulge, in the... more We compare the populations of Red Giant stars and Planetary Nebulae in the Galactic Bulge, in the light of recent determinations of their abundances patterns. We find both populations to be compatible. From the planetary nebulae, we find evidences that the Bulge did not form stars recently. The whole abundances pattern remains however puzzling, some elements favoring a quick evolution of the Galactic Bulge (Mg and Ti), and others a much slower one (He, O, Si, S, Ar and Ca).
A planetarium show highlighting the ALMA project is being jointly prepared by ESO and the Associa... more A planetarium show highlighting the ALMA project is being jointly prepared by ESO and the Association des Planétariums de Langue Française.
ABSTRACT We report discovery of ~500 planetary nebulae (PNe) in the central 200 sq.deg of the Gal... more ABSTRACT We report discovery of ~500 planetary nebulae (PNe) in the central 200 sq.deg of the Galactic Bulge from the AAO/UKST Halpha survey. Confirmatory UKST 6dF fibre spectroscopy and additional follow-up on 2-m class telescopes has led to a doubling of known Bulge PNe. This new population will have important implications for the bulge PN luminosity function and will provide improved determination of abundance gradients, a better picture of chemical evolution, as well as valuable test particles for dynamical studies.
... E. Lagadec, O. Chesneau, M. Matsuura, O. De Marco, JA de Freitas Pacheco, AA Zijlstra, A. Ack... more ... E. Lagadec, O. Chesneau, M. Matsuura, O. De Marco, JA de Freitas Pacheco, AA Zijlstra, A. Acker, GC Clayton. Abstract. We report infrared observations of the planetary nebula Hen 2‐113 obtained with VLT/NACO, VLTI/MIDI, VLT/ISAAC and TIMMI at the ESO 3.6m. Hen 2‐113 ...
The table lists the heliocentric radial velocities for planetary nebulae in the direction of the ... more The table lists the heliocentric radial velocities for planetary nebulae in the direction of the Galactic bulge. The accuracy is about 2km/s. The measurements were made in June and July 1993, using the ESO CAT with spectral resolution of 30000-60000. Halpha, [NII] 6548 and 6584 and [O III] 5007 were observed. (1 data file).
The exploitation of data from the Halpha southern survey and from the spectroscopic survey of new... more The exploitation of data from the Halpha southern survey and from the spectroscopic survey of newly discovered planetary nebulae (PN) is focussed on the 1500 PN of the galactic bulge, with the following objectives: -- history of expansion linked to the evolutive models as a function of progenitor mass; -- spatial distribution and kinematics to constrain the dynamics.
PN are excellent tracers for Galactic bulge dynamical studies because they are less affected by m... more PN are excellent tracers for Galactic bulge dynamical studies because they are less affected by metallicity bias than other tracers and have strong emission lines permitting accurate velocity determinations. Due to the relatively small numbers previously known throughout the Galaxy (i.e. ~1500) compared to those expected ~20000+) their potential as tracers of galactic structure and as windows to stellar evolution in the critical phase between PN and White Dwarf has only been partially realized. Furthermore, the number of bulge PN available for such studies has, until now, also been quite small (e.g. Zijlstra et al. 1997 and Beaulieu et al. 1999) so their potential as test particles of bulge dynamics and PN evolution also remains largely unrealised. We present our new PNe sample and an axisymmetrical model of the Bulge that we will be able to constrain.
Coordinates for 288 planetary nebulae searched for photometric variations in OGLE-III. Remarks ar... more Coordinates for 288 planetary nebulae searched for photometric variations in OGLE-III. Remarks are given according to the central star (CSPN) identification process detailed in the paper. For each planetary nebula the OGLE-III field, PN G designation, common name, equatorial coordinates and central star ID are given. (1 data file).
The Macquarie/AAO/Strasbourg Halpha Planetary Nebula Catalogue (MASH) contains 903 new true, like... more The Macquarie/AAO/Strasbourg Halpha Planetary Nebula Catalogue (MASH) contains 903 new true, likely and possible Galactic Planetary Nebulae (PNe) discovered from the AAO/UKST Halpha survey of the southern Galactic plane. The combination of depth, resolution, uniformity, and areal coverage of the H {alpha}survey has opened up an hitherto unexplored region of parameter space permitting the detection of this significant new PN sample. This catalogue includes also the spectra of the PNe as FITS files (in the "sp" subdirectory), and a gallery of images created as a combination of the Halpha and short red images of the survey. The second part, MASH-II (table mash2.dat) consists of over 300 true, likely and possible new Galactic PNe found after re-examination of the entire AAO/UKST Halpha survey of the Southern Galactic Plane in digital form. Over 240 of these new candidates were confirmed as bona fide PNe on the basis of spectroscopic observations. The spectra of this supplement...
Detection of close binary central stars with periods of less than a day is now well-tested and ro... more Detection of close binary central stars with periods of less than a day is now well-tested and routinely possible via photometric monitoring. For wide binary central stars with periods of weeks to years detection techniques are still in their infancy. Radial velocity monitoring programs are yet to be applied to very large samples and the method suffers from large systematic errors as well as intrinsic wind variability. One alternative we are exploring is the detection of dense circumstellar nebulae residing around a wide companion. The archetype of this class is EGB6 as revealed by HST imaging (Bond 2009). Here we present spectroscopic evidence for other EGB6-like central stars and discuss their relationship to symbiotic stars. A probable 12.5-day irradiated binary is also presented to demonstrate the limits of the photometric monitoring technique.
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Papers by Agnes Acker