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13 results on '"Lykou, Foteini"'

1. The messy death of a multiple star system and the resulting planetary nebula as observed by JWST

Author

De Marco, Orsola, Akashi, Muhammad, Akras, Stavros, Alcolea, Javier, Aleman, Isabel, Amram, Philippe, Balick, Bruce, De Beck, Elvire, Blackman, Eric G., Boffin, Henri M. J., Boumis, Panos, Bublitz, Jesse, Bucciarelli, Beatrice, Bujarrabal, Valentin, Cami, Jan, Chornay, Nicholas, Chu, You-Hua, Corradi, Romano L. M., Frank, Adam, García-Hernández, D. A., García-Rojas, Jorge, García-Segura, Guillermo, Gómez-Llanos, Veronica, Gonçalves, Denise R., Guerrero, Martín A., Jones, David, Karakas, Amanda I., Kastner, Joel H., Kwok, Sun, Lykou, Foteini, Manchado, Arturo, Matsuura, Mikako, McDonald, Iain, Miszalski, Brent, Mohamed, Shazrene S., Monreal-Ibero, Ana, Monteiro, Hektor, Montez, Jr, Rodolfo, Baez, Paula Moraga, Morisset, Christophe, Nordhaus, Jason, Mendes de Oliveira, Claudia, Osborn, Zara, Otsuka, Masaaki, Parker, Quentin A., Peeters, Els, Quint, Bruno C., Quintana-Lacaci, Guillermo, Redman, Matt, Ruiter, Ashley J., Sabin, Laurence, Sahai, Raghvendra, Contreras, Carmen Sánchez, Santander-García, Miguel, Seitenzahl, Ivo, Soker, Noam, Speck, Angela K., Stanghellini, Letizia, Steffen, Wolfgang, Toalá, Jesús A., Ueta, Toshiya, Van de Steene, Griet, Van Winckel, Hans, Ventura, Paolo, Villaver, Eva, Vlemmings, Wouter, Walsh, Jeremy R., Wesson, Roger, and Zijlstra, Albert A.

Published
2022
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2. Author Correction: The messy death of a multiple star system and the resulting planetary nebula as observed by JWST

Author

De Marco, Orsola, Akashi, Muhammad, Akras, Stavros, Alcolea, Javier, Aleman, Isabel, Amram, Philippe, Balick, Bruce, De Beck, Elvire, Blackman, Eric G., Boffin, Henri M. J., Boumis, Panos, Bublitz, Jesse, Bucciarelli, Beatrice, Bujarrabal, Valentin, Cami, Jan, Chornay, Nicholas, Chu, You-Hua, Corradi, Romano L. M., Frank, Adam, García-Hernández, D. A., García-Rojas, Jorge, García-Segura, Guillermo, Gómez-Llanos, Veronica, Gonçalves, Denise R., Guerrero, Martín A., Jones, David, Karakas, Amanda I., Kastner, Joel H., Kwok, Sun, Lykou, Foteini, Manchado, Arturo, Matsuura, Mikako, McDonald, Iain, Miszalski, Brent, Mohamed, Shazrene S., Monreal-Ibero, Ana, Monteiro, Hektor, Montez, Jr, Rodolfo, Baez, Paula Moraga, Morisset, Christophe, Nordhaus, Jason, Mendes de Oliveira, Claudia, Osborn, Zara, Otsuka, Masaaki, Parker, Quentin A., Peeters, Els, Quint, Bruno C., Quintana-Lacaci, Guillermo, Redman, Matt, Ruiter, Ashley J., Sabin, Laurence, Sahai, Raghvendra, Contreras, Carmen Sánchez, Santander-García, Miguel, Seitenzahl, Ivo, Soker, Noam, Speck, Angela K., Stanghellini, Letizia, Steffen, Wolfgang, Toalá, Jesús A., Ueta, Toshiya, Van de Steene, Griet, Van Winckel, Hans, Ventura, Paolo, Villaver, Eva, Vlemmings, Wouter, Walsh, Jeremy R., Wesson, Roger, and Zijlstra, Albert A.

Published
2023
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3. Dusty discs around evolved stars

Author

Lykou, Foteini and Zijlstra, Albert

Subjects
523.8, interferometry, dust, discs, stellar evolution, AGB stars, planetary nebulae
Abstract

From the main sequence onwards, stars of intermediate masses (1-8 Solar masses) eject a large portion of their mass with rates as high as 0.0001 Solar masses per year during their transition through the Asymptotical Giant Branch (AGB) stage. The outflows are shaped by the same mechanisms that shape the ejecta, which in turn appear to depart from spherical symmetry as early as the AGB stage. The ejecta are then evolving into asymmetrical structures. Stars like that are giant factories of dust, responsible for the enrichment of their surrounding Galactic medium in metals heavier than helium. Depending on their abundances during the AGB stage, the stars are either oxygen-rich or carbon-rich, and as such, the dust produced in their atmospheres is either O-rich or C-rich. The chemical composition of the ejecta, indicates the stellar chemistry at the moment of ejection. The disruption of the spherical symmetry of the mass loss can be caused by fast rotation, stellar magnetic fields or binarity, the latter being the most efficient and favourable mechanism. Such mechanisms can lead to the creation of circumstellar, equatorial, dusty structures, like discs, torii or spirals. Due to their small relative sizes, compared to their surrounding nebulae, they can be studied at best with the use of infrared interferometric techniques. We report the discovery of three such structures in sources at three different evolutionary stages, respectively, with the use of single- and multi-aperture interferometry. In the C-rich AGB star V Hya we imaged via aperture masking in the near-infrared, a complex and possibly orbiting structure, which is embedded within the star's molecular torus. Our MIDI observations in the mid-infrared have revealed, a silicate disc within the symbiotic nebula M2-9 that is currently being shaped by the central binary system within its core, and a C-rich disc-like structure in the born-again star Sakurai's Object, that is also aligned to an asymmetry found in its surrounding planetary nebula. Finally, we compare the properties of the structures found here with those found in the literature in order to establish a relation between late stellar evolution and the existence of dusty structures.

Published
2013

4. A New Study on a Type Iax Stellar Remnant and its Probable Association with SN 1181.

Author

Lykou, Foteini, Parker, Quentin A., Ritter, Andreas, Zijlstra, Albert A., Hillier, D. John, Guerrero, Martín A., and Le Dû, Pascal

Subjects
*COMPACT objects (Astronomy), *PLANETARY nebulae, *STELLAR photometry, *STELLAR winds, *TERMINAL velocity, *WHITE dwarf stars
Abstract

We report observations and modeling of the stellar remnant and presumed double-degenerate merger of Type Iax supernova Pa 30, which is the probable remnant of SN 1181 AD. It is the only known bound stellar SN remnant and the only star with Wolf–Rayet features that is neither a planetary nebula central star nor a massive Population I progenitor. We model the unique emission-line spectrum with broad, strong O vi and O viii lines as a fast stellar wind and shocked, hot gas. Non-LTE wind modeling indicates a mass-loss rate of ∼10−6 M ⊙ yr−1 and a terminal velocity of ∼15,000 km s−1, consistent with earlier results. O viii lines indicate shocked gas temperatures of T ≃ 4 MK. We derive a magnetic field upper limit of B < 2.5 MG, below earlier suggestions. The luminosity indicates a remnant mass of 1.0–1.65 M ⊙ with ejecta mass 0.15 ± 0.05 M ⊙. Archival photometry suggests the stellar remnant has dimmed by ∼0.5 mag over 100 yr. A low Ne/O < 0.15 argues against an O-Ne white dwarf in the merger. A cold dust shell is only the second detection of dust in an SN Iax and the first of cold dust. Our ejecta mass and kinetic energy estimates of the remnant are consistent with Type Iax extragalactic sources. [ABSTRACT FROM AUTHOR]

Published
2023
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6. The infrared view of dust and molecules around V4334 Sgr (Sakurai's object): a 20-yr retrospective.

Author

Evans, A, Gehrz, R D, Woodward, C E, Banerjee, D P K, Geballe, T R, Clayton, G C, Sarre, P J, Starrfield, S, Hinkle, K, Joyce, R R, Lykou, Foteini, Helton, L A, Eyres, S P S, Worters, H, Montiel, E J, Liimets, T, Zijlstra, A, Richter, M, and Krautter, J

Subjects
CIRCUMSTELLAR matter, MOLECULAR spectra, AMORPHOUS carbon, SOLAR system, DUST, HYDROCYANIC acid, ASTROCHEMISTRY, CORONAL mass ejections
Abstract

We present an analysis of the evolution of circumstellar dust and molecules in the environment of the very late thermal pulse object V4334 Sgr (Sakurai's object) over an ∼20-yr period, drawing on ground-, airborne-, and space-based infrared photometry and spectroscopy. The dust emission, which started in 1997, resembles a blackbody that cooled from ∼1200 K in 1998 August to ∼180 K in 2016 July. The dust mass, assuming amorphous carbon, was ∼5 × 10−10 M⊙ in 1998 August, and we estimate that the total dust mass was ∼2 × 10−5 M⊙ by ∼2016. The appearance of a near-infrared excess in 2008 suggests that a new episode of (or renewed) mass-loss began then. We infer lower limits on the bolometric luminosity of the embedded star from that of the dust shell, which rose to ∼16 000 L⊙ before declining to ∼3000 L⊙. There is evidence for weak 6–7  μ m absorption, which we attribute to hydrogenated amorphous carbon formed in material ejected by Sakurai's object during a mass ejection phase that preceded the 1997 event. We detect small hydrocarbon and other molecules in the spectra, and trace the column densities in hydrogen cyanide (HCN) and acetylene (C2H2). We use the former to determine the 12C/13C ratio to be 6.4 ± 0.7, 14 times smaller than the Solar system value. [ABSTRACT FROM AUTHOR]

Published
2020
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7. The curious case of II Lup: a complex morphology revealed with SAM/NACO and ALMA.

Author

Lykou, Foteini, Zijlstra, A A, Kluska, J, Lagadec, E, Tuthill, P G, Avison, A, Norris, B R M, and Parker, Q A

Subjects
*VERY large telescopes, *CIRCUMSTELLAR matter, *HIGH resolution imaging, *ASTRONOMICAL observations
Abstract

We present the first-ever images of the circumstellar environment of the carbon-rich asymptotic giant branch (AGB) star II Lup in the infrared and sub-mm wavelengths, and the discovery of the envelope's non-spherical morphology with the use of high angular resolution imaging techniques with the sparse aperture masking mode on NACO/Very Large Telescope (which enables diffraction-limited resolution from a single telescope) and with the Atacama Large Millimeter/submillimeter Array (ALMA). We have successfully recovered images in Ks (2.18  $$\mu$$ m), L' (3.80  $$\mu$$ m), and M' (4.78  $$\mu$$ m) that revealed the non-spherical morphology of the circumstellar envelope around II Lup. The stellar surface of the AGB star is unresolved (i.e. ≤30 mas in Ks), however, the detected structure extends up to 110 mas from the star in all filters. Clumps have been found in the Ks maps, while at lower emission levels a hook-like structure appears to extend counterclockwise from the south. At larger spatial scales, the circumstellar envelope extends up to approximately 23 arcsec, while its shape suggests a spiral at four different molecules, namely CO, SiO, CS, and HC3N, with an average arm spacing of 1.7 arcsec that would imply an orbital period of 128 yr for a distance of 590 pc. [ABSTRACT FROM AUTHOR]

Published
2018
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8. Asymmetric Planetary Nebulae V. Conference proceedings

Author

Zijlstra, Albert, Lykou, Foteini, Lagadec, Eric, and McDonald, Iain

Subjects
Planetary Nebulae, Astrophysics
Abstract

The Asymmetric Planetary Nebulae V meeting was held in Bowness-on-Windermere, 20-25 June 2010. These are the full proceedings of this conference Contents Welcometo AsymmetricPlanetaryNebulae 5 ................... iii Albert Zijlstra In memoriam: John Edward Dyson . . . . . . . . . . . . . . . . . . . . . . . . . v Tom Hartquist Closing summary APN1 .............................. vii F. D. Kahn Whitepaper: the RochesterCollaborative ..................... xix Participants .....................................xxxv Conference Photograph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxix Planetary Nebula Surveys: Past, Presentand Future . . . . . . . . . . . . . . . . 1 Q. A. Parker and D. J. Frew Hunting for Shaping Mechanisms in the Progenitors of Aspherical Planetary Nebulae.................................... 11 R. Sahai Proto-Planetary Nebulae with the Spitzer Space Telescope . . . . . . . . . . . . 18 A. Hart et al. Imaging PNe with Herschel-PACS and SPIRE................... 23 P. A. M. van Hoof et al. Origin of Morphological Structures of Planetary Nebulae . . . . . . . . . . . . . 28 Sun Kwok A view of the solar neighbourhood: the local population of planetary nebulae and their mimics ................................. 33 D. J. Frew and Q. A. Parker Iron Depletion into Dust Grains in Galactic Planetary Nebulae . . . . . . . .40 G. Delgado-Inglada and M. Rodr ́ıguez A new [Oiii] λ5007 Å Galactic Bulge Planetary Nebula Luminosity Function ..44 Kovacevic et al. A New Luminosity Function for PNe in the Large Magellanic Cloud . . . . .49 W. A. Reid and Q. A. Parker Symmetric vs. asymmetric planetary nebulae: morphology and chemical abundances .................................... 54 W. J. Maciel and R. D. D. Costa MasslossattheAGBandbeyondandtheasymmetryconundrum. . . . . . . . . 58 J. Alcolea Structure and shaping processes within the extended atmospheres of AGB stars . 66 M. Wittkowski et al. Measuring and modeling massive stellar winds at the tip of the asymptotic giant branch .................................... 72 C. Sandin Unexpected AGB Asymmetries........................... 76 A. M. S. Richards et al. W43A: magnetic field and morphology....................... 81 N. Amiri, H. van Landevelde and W. Vlemmings Morphology of Planetary Nebulae with Water Maser Emission . . . . . . . . .85 D. Tafoya et al. Magnetic fields around (post-)AGB stars and (Pre-)Planetary Nebulae . . . . .8 W. H. T. Vlemmings . Dust at sub-solar metallicity: the case of post-AGB stars in the Large Magellanic Cloud..................................... 97 M. Matsuura et al. A VISIR/VLT imaging survey of post-AGBstars . . . . . . . . . . . . . . . . . 104 E. Lagadec Point-Symmetry types in Planetary Nebulae ....................109 L. Sabin et al. Planetary Nebula Models: From Core to Outflow . . . . . . . . . . . .114 A. Frank Integral field spectroscopy of IRAS 18276-1431 and IRAS 16342-3814 ...122 T. M. Gledhill and K. P. Forde Fast, gusty winds blowing from the core of the pPNM2-56 . . . . . . .126 C. Sa ́nchez-Contreras et al. 3-D Study of the Glowing Eye Nebula, NGC6751. . . . . . . . . . . .131 D. M. Clark et al. Modelling H2 Infrared Emission of the Helix Nebula Cometary Knots ..135 I. Aleman et al. On the construction of a database to search for ICFs that account for asymmetri- cal nebulae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139 D. R. Goncalves et al. Stellar evolution from the main sequence to the post-AGB phase . . . . . . . .144 A. I. Karakas The connection between sequence D and sequence E red giant variables and asymmetricplanetarynebulae ........................152 C. P. Nicholls and P. R. Wood The Evolutionary History of the R Coronae Borealis Stars. . . . . . . . . . . . . 157 G. C. Clayton Wolf-Rayet Central Stars of Planetary Nebulae: Their Evolution and Properties . 160 K. DePew et al. UV Spectroscopy of the Central Star of the Planetary Nebula A 43 . . . . . . . . 165 E. Ringat et al. Modeling Ejecta of Massive Stars .........................170 R. Townsend Eta Carinae, Present and Past . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 V. Icke Jets and winds from binary stars ..........................185 A. C. Raga et al. The Turbulent Destruction of Circumstellar Clouds . . . . . . . . . . . . . . .192 J. M. Pittard Physical conditions and excitation of FLIERs . . . . . . . . . . . . . . . . . .198 A. Riera et al. Criss-cross mapping BD+30 3639: a new kinematic analysis technique . . . . .203 W. Steffen et al. From Bipolar to Elliptical: Morphological Changes in the Temporal Evolution of PN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208 M Huarte-Espinosa et al. Mira: a wonderful prospect . . . . . . . . . . . . . . . . . . . . . . . . . . . .213 C. J. Wareing Observations of dusty torii and compact disks around evolved stars: the high spatial resolution infrared view .......................218 O. Chesneau Stable discs around Galactic and LMC post-AGBbinaries. . . . . . . . . . . .226 C. Gielen et al. Dusty discs around evolved stars observed at high angular resolution . . . . . .233 F. Lykou et al. A circumbinary dust disc in the making: the semi-detached evolved binary SS Leporis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .237 T. Verhoelst, E. van Aarle and B. Acke IR Excesses of Central Stars of Planetary Nebulae . . . . . . . . . . . . . . . .241 J. Bilikova et al. HERMES Survey of Binarity in Evolved Stars . . . . . . . . . . . . . . . . . .246 N. Gorlova et al. New results on planetary nebula shaping and stellar binarity . . . . . . . . . . .251 O. De Marco The binary central stars of PNe with the shortest orbital periods . . . . . . . . .259 M. Santander-Garc ́ıa et al. Are PPNe Shaped by a Binary? Results of Long-Term Radial Velocity and Light CurveStudies ................................265 B. J. Hrivnak Post-AGB stars in the LMC as tracers of (binary) stellar evolution . . . . . . .270 E. van Aarle et al. The Physical Characteristics of Binary Central Stars of Planetary Nebulae . . .275 T. C Hillwig Variability of Central Stars of Planetary Nebulae in the ASAS survey . . . . . .280 M. Hajduk, A. A. Zijlstra and K. Gesicki The Rise and Phall of the Barium Stars . . . . . . . . . . . . . . . . . . . . . .284 R. G. Izzard, T Dermine and R. P. Church Two Populations of Companions around White Dwarfs: The Effect of Tides and Tidal Engulfment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .290 J. Nordhaus Modelling the Asymmetric Outflows of Mira-type Binaries . . . . . . . . . . .295 S. Mohamed and Ph. Podsiadlowski Asymmetry in Common Envelope Ejecta . . . . . . . . . . . . . . . . . . . . .300 B. Fitzpatrick and Ph. Podsiadlowski Drawingparallelsbetweenplanetariesandnovae . . . . . . . . . . . . . . . .305 A. Evans Exploring the Morphology of the Expanding Remnants of Classical and Recur- rent Novae ..................................314 V. A. R. M. Ribeiro et al. Models of interacting winds in the 2006 outburst of RS Ophiuchi . . . . . . . . . 318 N. Vaytet et al. Multiwavelength modeling the SED of stellar explosions . . . . . . . . . . . . . 323 A. Skopal Prediction of close binarity based on planetary nebula morphology . . . . . . . . 328 B. Miszalski et al. The kinematics and morphology of PNe with close binary nuclei . . . . . . . . . 335 J. A. Lo ́pez et al. Abell 41: nebular shaping bya binary centralstar? . . . . . . . . . . . . . . . .340 D. Jones et al. The Necklace planetary nebula: equatorial and polar outflows from a post-common- envelope system ...............................344 R. L. M. Corradi et al. Watching PrePNe Evolve: 15 Years of HST Observations . . . . . . . . . . . . . 348 B. Balick et al. The Expanded Very Large Array and Observing AGB Stars, pPNe and PNe . . . 353 M. J. Claussen Prospects for Asymmetric PNe with ALMA ....................360 P. J. Huggins APNV: A Highly Skewed and Biased Conference Summary . . . . . . . . . . . 368 J. H. Kastner &nbsp

Published
2011
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10. On the Age of Galactic Bulge CSPNe: Too Young and Complicated?

Author

Lykou, Foteini, Zijlstra, Albert, and Parker, Quentin A.

Subjects
GALACTIC bulges, PLANETARY nebulae, NEBULAE, STELLAR mass, AGE of stars, SPACE telescopes
Abstract

We present preliminary results of our study of a small sample of planetary nebulae in the Galactic Bulge for which high-angular resolution Hubble Space Telescope imaging is available. From this and from archival spectroscopy, we were able to calculate temperatures and luminosities for their central stars. These were then correlated to up-to-date evolutionary tracks found in the literature to help us estimate stellar masses and therefore ages for the central stars. Our current analysis indicates that our sample appears to represent a somewhat mixed population of planetary nebulae central stars, while at least one of the nebulae might have been formed by a more massive progenitor (i.e., M ZAMS ∼ 4 M ⊙ ). [ABSTRACT FROM AUTHOR]

Published
2020
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11. Zooming into the complex dusty envelopes of C-rich AGB stars.

Author

Lykou, Foteini, Hron, Josef, and Klotz, Daniela

Abstract

Recent advances in high-angular resolution instruments (VLT and VLTI, ALMA) have enabled us to delve deep into the circumstellar envelopes of AGB stars from the optical to the sub-mm wavelengths, thus allowing us to study in detail the gas and dust formation zones (e.g., their geometry, chemistry and kinematics). This work focuses on four (4) C-rich AGB stars observed with a high-angular resolution technique in the near-infrared: a multi-wavelength tomographic study of the dusty layers of the circumstellar envelopes of these C-rich stars, i.e. the variations in the morphology and temperature distribution. [ABSTRACT FROM AUTHOR]

Published
2018
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12. Central Stars of Planetary Nebulae in Galactic Open Clusters: Providing additional data for the White Dwarf Initial-to-Final-Mass Relation.

Author

Fragkou, Vasiliki, Parker, Quentin A., Zijlstra, Albert, Shaw, Richard, and Lykou, Foteini

Abstract

Accurate (< 10%) distances of Galactic star clusters allow a precise estimation of the physical parameters of any physically associated Planetary Nebula (PN) and also that of its central star (CSPN) and its progenitor. The progenitor's mass can be related to the PN's chemical characteristics and, furthermore, provides additional data for the widely used white dwarf (WD) initial-to-final mass relation (IFMR) that is crucial for tracing the development of both carbon and nitrogen in entire galaxies. To date, there is only one PN (PHR1315- 6555) confirmed to be physically associated with a Galactic open cluster (ESO 96 -SC04) that has a turn-off mass ∼2Mʘ. Our deep HST photometry was used for the search of the CSPN of this currently unique PN. In this work, we present our results. [ABSTRACT FROM AUTHOR]

Published
2018
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13. Infrared Observations of the Asymmetric Mass Loss of an AGB Star.

Author

Lykou, Foteini, Zijlstra, Albert A., Kluska, Jacques, Lagadec, Eric, Tuthill, Peter G., Avison, Adam, Norris, Barnaby R. M., and Parker, Quentin A.

Subjects
ASYMPTOTIC giant branch stars, MASS loss (Astrophysics), INTERFEROMETRY, CIRCUMSTELLAR matter, STELLAR evolution
Abstract

We report on the observations of the circumstellar envelope of the AGB star II Lup in the near- and mid-infrared with the use of direct imaging and interferometric techniques. Our findings indicate that the circumstellar envelope is not spherically symmetric and that the majority of the emission originates within 0.5 arcsec from the star. [ABSTRACT FROM AUTHOR]

Published
2018
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