This project has three major objectives: 1) To determine the physico-chemical characteristics of bipolar planetary nebulae and symbiotic nebulae, to help understanding the origin of bipolarity and to test theoretical models, mainly models with binary central stars, aimed at explaining the observed morphology and kinematics. 2) To study the low-ionization microstructures in planetary nebulae, their origin (in the context of the main shell formation), their physico-chemical characteristics, and their interaction with the nebular gas. 3) To discover and study galactic and extragalactic planetary nebulae, analyzing their physico-chemical properties and the metallicity gradients along the galactic discs.
Miszalski, B and collaborators (2016, MNRAS, 456, 633) re-discovered a dwarf nova system, an eruption of which was first observed by ancient Chinese astronomers in the year 483 CE. Hillwig, T and collaborators (2016, ApJ, 832, 125) demonstrated that the symmetry axes of planetary nebulae with binary central stars always lie perpendicular to the orbital plane of the central binaries. The probability of encountering such a tight correlation by chance is less than a million to one.
When nature tries to trick us. An eclipsing eccentric close binary superposed on the central star of the planetary nebula M 3-2
Bipolar planetary nebulae (PNe) are thought to result from binary star interactions and, indeed, tens of binary central stars of PNe have been found, in particular using photometric time-series that allow for the detection of post-common envelope systems. Using photometry at the NTT in La Silla we have studied the bright object close to the centreBoffin, H. M. J. et al.
Opening PANDORA's box: APEX observations of CO in PNe
Context. Observations of molecular gas have played a key role in developing the current understanding of the late stages of stellar evolution. Aims: The survey Planetary nebulae AND their cO Reservoir with APEX (PANDORA) was designed to study the circumstellar shells of evolved stars with the aim to estimate their physical parameters. MethodsGuzman-Ramirez, L. et al.
Confirmation of the link between central star binarity and extreme abundance discrepancy factors in planetary nebulae
It has recently been noted that there seems to be a strong correlation between planetary nebulae with close binary central stars and highly enhanced recombination line abundances. We present new deep spectra of seven objects known to have close binary central stars, and find that the heavy element abundances derived from recombination lines exceedWesson, R. et al.
On ɛ-mechanism-driven pulsations in VV 47
We report new observations of the central star of the planetary nebula VV 47 carried out to verify earlier assertions that the short-period pulsation modes detected in the star are driven by the ɛ-mechanism. In our data, VV 47 was not variable up to a limit of 0.52 mmag in the Fourier amplitude spectrum up to the Nyquist frequency of 21.7 mHzSowicka, P. et al.
New insights into the outflows from R Aquarii
Context. The source R Aquarii is a symbiotic binary surrounded by a large and complex nebula with a prominent curved jet. It is one of the closest known symbiotic systems, and therefore offers a unique opportunity to study the central regions of these systems and the formation and evolution of astrophysical jets. Aims: We aim to study the evolutionLiimets, T. et al.
A deep narrowband survey for planetary nebulae at the outskirts of M 33
Context. Planetary nebulae (PNe) are excellent tracers of stellar populations with low surface brightness, and therefore provide a powerful method to detect and explore the rich system of substructures discovered around the main spiral galaxies of the local group. Aim. We searched the outskirts of the local group spiral galaxy M 33 (the Triangulum)Galera-Rosillo, R. et al.
A new look inside planetary nebula LoTr 5: a long-period binary with hints of a possible third component
LoTr 5 is a planetary nebula with an unusual long-period binary central star. As far as we know, the pair consists of a rapidly rotating G-type star and a hot star, which is responsible for the ionization of the nebula. The rotation period of the G-type star is 5.95 d and the orbital period of the binary is now known to be ˜2700 d, one of theAller, A. et al.
The binary fraction of planetary nebula central stars - III. the promise of VPHAS+
The majority of planetary nebulae (PNe) are not spherical, and current single-star models cannot adequately explain all the morphologies we observe. This has led to the Binary Hypothesis, which states that PNe are preferentially formed by binary systems. This hypothesis can be corroborated or disproved by comparing the estimated binary fraction ofBarker, H. et al.
280 one-opposition near-Earth asteroids recovered by the EURONEAR with the Isaac Newton Telescope
Context. One-opposition near-Earth asteroids (NEAs) are growing in number, and they must be recovered to prevent loss and mismatch risk, and to improve their orbits, as they are likely to be too faint for detection in shallow surveys at future apparitions. Aims: We aimed to recover more than half of the one-opposition NEAs recommended forVaduvescu, O. et al.
The planetary nebula IC 4776 and its post-common-envelope binary central star
We present a detailed analysis of IC 4776, a planetary nebula displaying a morphology believed to be typical of central star binarity. The nebula is shown to comprise a compact hourglass-shaped central region and a pair of precessing jet-like structures. Time-resolved spectroscopy of its central star reveals a periodic radial velocity variabilitySowicka, P. et al.
A hybrid type Ia supernova with an early flash triggered by helium-shell detonation
Type Ia supernovae arise from the thermonuclear explosion of white-dwarf stars that have cores of carbon and oxygen. The uniformity of their light curves makes these supernovae powerful cosmological distance indicators, but there have long been debates about exactly how their explosion is triggered and what kind of companion stars are involved. ForJiang, Ji-An et al.
Search for exoplanets around pulsating stars of A-F type in Kepler short-cadence data and the case of KIC 8197761
We searched for extrasolar planets around pulsating stars by examining Kepler data for transit-like events hidden in the intrinsic variability. All short-cadence observations for targets with 6000 < Teff < 8500 K were visually inspected for transit-like events following the removal of pulsational signals by sinusoidal fits. Clear transit-likeSowicka, Paulina et al.
Binary stars as the key to understanding planetary nebulae
Planetary nebulae are traditionally considered to represent the final evolutionary stage of all intermediate-mass stars (∼0.7-8 M⊙). Recent evidence seems to contradict this picture. In particular, since the launch of the Hubble Space Telescope, it has been clear that planetary nebulae display a wide range of striking morphologies that cannot beJones, D. et al.
The long-period binary central stars of the planetary nebulae NGC 1514 and LoTr 5
The importance of long-period binaries for the formation and evolution of planetary nebulae is still rather poorly understood, which in part is due to the lack of central star systems that are known to comprise such long-period binaries. Here, we report on the latest results from the on-going Mercator-HERMES survey for variability in the centralJones, D. et al.
On the possible triple central star system of PN SuWt 2: no ménage à trois at the heart of the Wedding Ring
SuWt 2 is a planetary nebula consisting of a bright ring-like waist from which protrude faint extended lobes - a morphology believed to be typical of progenitors which have experienced a close-binary evolution. Previous observations of NSV 19992, the star at the projected centre of SuWt 2, have found it to comprise two A-type stars in a 4.9 dJones, D. et al.
Chemical distribution of H II regions towards the Galactic anticentre
Context. The study of the radial variations of metallicity across the Galactic disc is a powerful method for understanding the history of star formation and chemical evolution of the Milky Way. Although several studies about gradients have been performed so far, the knowledge of the Galactic antincentre is still poor. Aims: This work aims toFernández-Martín, A. et al.
ALMA high spatial resolution observations of the dense molecular region of NGC 6302
Context. The mechanism behind the shaping of bipolar planetary nebulae is still poorly understood. It is becoming increasingly clear that the main agents must operate at their innermost regions, where a significant equatorial density enhancement should be present and related to the collimation of light and jet launching from the central starSantander-García, M. et al.
Co-spatial Long-slit UV/Optical Spectra of Ten Galactic Planetary Nebulae with HST/STIS. II. Nebular Models, Central Star Properties, and He+CNO Synthesis
The goal of the present study is twofold. First, we employ new HST/STIS spectra and photoionization modeling techniques to determine the progenitor masses of eight planetary nebulae (IC 2165, IC 3568, NGC 2440, NGC 3242, NGC 5315, NGC 5882, NGC 7662, and PB 6). Second, for the first time we are able to compare each object’s observed nebularHenry, R. B. C. et al.
The post-common envelope central stars of the planetary nebulae Henize 2-155 and Henize 2-161
We present a study of Hen 2-155 and Hen 2-161, two planetary nebulae which bear striking morphological similarities to other planetary nebulae known to host close-binary central stars. Both central stars are revealed to be photometric variables while spectroscopic observations confirm that Hen 2-155 is host to a double-eclipsing, post-commonJones, D. et al.
Binary Central Stars of Planetary Nebulae Discovered Through Photometric Variability. III. The Central Star of Abell 65
A growing number of close binary stars are being discovered among central stars of planetary nebulae. Recent and ongoing surveys are finding new systems and contributing to our knowledge of the evolution of close binary systems. The push to find more systems was largely based on early discoveries which suggested that 10%–15% of all central starsSchaub, S. C. et al.