The ALMA bipolar planetary nebula in formation, W43A, is an aged star located 7,000 light years away in the constellation Aquila. W43A, an old star located 7,000 light years away in the constellation Aquila, a high-speed bipolar jet less than 60 years old, according to new research published in the astrophysics magazine Letters. W43 An impression of an artist.
NAOJ’s picture. “Sun-like stars turn reddish-brown pigments in the last stages of their lives. Then, the star expelled the gas to form a relic like a nebula, “Dr. Daniel Tafoya, astronomer and co-worker at the Technological University of Chalmers, Sweden.
There is a great variation in the shape of the planet’s nebula: some are spherical, but others are dipolar or show complex structures. Astronomers are interested in the origin of this variety, but hide the thick dust and gas system expelled by an old star and make it difficult to investigate the internal functioning of the process.
To tackle this problem, astronomers used the Atacama Large Millimeter / Submillimeter Array (ALMA) matrix to observe the W43A. Thanks to the high resolution of ALMA, they obtained a very detailed view of the location around the W43A. The most notable structure is its small dipole jet, Drs. Tafoya said.
The researchers found that the speed of the jet is approximately 175 km / s (109 mi / s), which is much higher than previous estimates. Based on this speed and the size of the plane, they calculated that the age of the plane was less than human life. ALMA image of the W43A system.
And high-speed dipole jets ejected from the central aged star are seen in blue and the low velocity outflow is shown in green, and dust clouds imposed by the jet are shown in orange. ALMA image of the W43A system; High velocity dipole jets ejected from the central aged star appear in blue, the low velocity outflow is shown in green.
And the dusty clouds planted by the jets are shown in orange. Image of ALMA / ESO / NAOJ / NRAO / Tafoya et al. Taking into account Jet’s youth compared to the general life of a star. It is safe to say that we are seeing the exact moment when the jets began to push through the surrounding gas, “said Dr. Tafoya.
“The jet passes through the surrounding material in approximately 60 years. A person can see his progress throughout his life. ” The image of ALMA clearly shows the distribution of dust clouds exerted by the jet, which shows that it is impacting the surroundings.
This barrier could be the key to creating a bipolar planetary nebula,” the scientists said. In our scenario, the aged star basically expels the gas spherically and the star’s core loses its envelope. “If the star has a partner, the partner’s gas is poured over the dying star’s core, and a part of this new gas forms a jet.”
Therefore, whether or not the old star’s partner is an important factor in determining the structure of the resulting planetary nebula. W43A is one of the strangest objects called ‘water sources’, Dr. Hiroshi Imai, a researcher at Kagoshima University, said.
“These are old stars that show specific radio emissions from water molecules. Our observations of ALMA lead us to think that the water heated to generate radio emissions is in the region of interface between the jet and the surrounding material. “Perhaps the sources of all these ‘water sources’ include a central binary system, which has just launched a new double jet for the W43A.”
Binary stars are the key to understanding the planet nebula. The planetary nebula is traditionally considered to represent the final evolutionary phase of all intermediate mass stars (☉0.7–8 M.7). Recent evidence seems to contradict this image.
In particular, since the launch of the Hubble Space Telescope, it has become clear that planetary nebulae exhibit a wide range of surprising morphology, pointing to binary evolution in most systems in a single-star landscape.
Here, we summarize our current understanding of the importance of duality in the formation and shape of planetary nebulae, and ask ourselves how recent observational studies have generally referred to our understanding of binary evolution.
It is revealed in These advances that have important implications for the understanding of the mass transfer processes in binary stars, particularly the very important but sometimes poorly understood normal envelope phase, as well as the cosmologically important type Ia supernova.
The planetary nebula (PN; singular, PN) are bright spheres of gas and dust seen around stars that have recently emerged from the asymptotic giant branch (AGB) and are evolving into the white dwarf phase.
The Misromer Planetary Nebula was created by Frederick William Herschel in the late 18th century in the context of his recent discovery, similar to the planet Uranus. PNs are important for understanding many areas of modern astrophysics.
They allow us to address issues related to fuller development, stellar populations, gas dynamics, and the formation of dust and molecules, including fullerenes 1. Given their brightness, they are also used to study the chemical and kinetic evolution of galaxy- 2, as well as to investigate the intracluster medium 5,6.
The extragalactic PNE is used as a standard sail 7.8. Since the late 1970s, PNE was thought to form as a result of an ice plow-like mechanism in which the mass was lost to the central star, while it was part of a red giant (slow stellar wind) then swept away by a stronger, but stronger, wind now exposed, the white pre-dwarf star core 9.
With some variations (namely 10 spherical winds), this model, known as generalized intermittent stellar winds, reproduces successfully a wide range of PN properties. However, when the Hubble Space Telescope allowed these objects to be seen in greater detail than before, it revealed large and small-scale structures that could not be explained with this simple model (Fig. 1).
The selection of planetary nebulae, known to harbor binary central stars, exposes the wide range of morphology observed in these objects. Several competing theories emerged to try to explain the many bisexual morphologies found in PN (about 20% are spherical, and the rest show deviations of the most admirable and often extreme, spherical 11).
The next three drew particularly significant attention from the community.. Stellar rotation. Rapid rotation can naturally cause a uniformly increased loss of mass, which varies with the evolutionary phase.b In the case of massive stars, interactions between different phases of rotation-driven mass loss have been shown to be capable of producing highly axial structures, such as rings and polar caps 12.
However, in PNE, it has been shown that although Rapid rotation may play a role in nebula formation with small deviations from spherical symmetry. It cannot reproduce most axial bipolar structures, because rotation for it will require higher rates for singles. stars13.
Magnetic field – Strong magnetic fields, in a range of equivalent structures, can act both along the axis of rotation, as a jet 14, and as a barrier to produce a bull-like characteristic 15 around the magnetic equator. However, it has been shown that in isolated PN ancestors.
Magnetic fields are not strong or durable enough to produce anything other than weak spherical symmetry deviations, rather than those required for magnetic fields. A binary partner is required to provide an angular momentum driven conformation 13,16.
Central duality of the star. In the early 1970s, the possibility of binary PN nuclei was contemplated, and was considered important evidence for the evolution of the common envelope (see explanation below).
Since then, binary interactions have become the preferred scenario for the formation of aqueous PN. Adjacent binaries provide a particularly clear path to the formation of axial structures, in which mass transfer processes act to accumulate more material in the binary’s orbital plane, thereby reducing post-bipolar winds or outlets.
As mentioned earlier, binary interactions can result in a dynamo effect that helps maintain relatively strong magnetic fields and therefore produces magnetically driven outputs, like those of the Jet 9.
Binary evolution, even in the main sequence, can vary dramatically for the development of a single star 20–22. Given the high binary fraction among solar-like main sequence stars 23, therefore, it is not surprising that forecasting can play an important role in the formation and evolution of NPs.
Theoretically, a link between forecasting and nebula structure is expected for several reasons. First, the models predict that some PNs should be the result of a dynamic event within a binary system, known as a normal envelope (CE) 24.
An AGB star in a binary system, unless the system is very broad, in some way way interacts with your partner. Specifically, if the orbital period is short enough, the AGB star will overflow its Roche lobe (the smallest surface of the gravitational system surrounding the binary system), which will generally result in a CE and a spiral in the pair.
The final class will be very tight, with an orbital period that varies from a few hours to a few days. In this case, the emitted EC is the nebula that will later be ionized by the resulting white dwarf. Such a PNe gives us the best CE Interactive 26 testing ground.
This is because the binaries in these PNs will be `freshly baked’: the shorter shelf life of PNs (around 50,000 years) and extremely deadlines. fast from the EC itself (generally believed to be a few years or so), very recent CE.
It has been ejected and therefore the orbital properties of the binaries represent a direct result of the CE process. By determining the correlations between stellar, binary, and PN parameters in these objects, invaluable limitations can be obtained in the CE 27 process.
This is particularly useful because the CE process is unfortunately one of the least understood steps in evolution. binary 28, despite its significant importance in many areas of astrophysics, for understanding the formation of type Ia supernovae 29 It is included.
The CE phase is also important for understanding object classes, such as catasemic variables, nova, low-mass x-ray binaries, and symbiotic stars. Furthermore, CE is a major topic in the theory of the formation of binary compact objects that give rise to detectable gravitational waves.
Furthermore, mass transfer in a different (wide) system can also cause density increases in the orbital plane, leading to spherical PNe30, given the loss of mass for PNB30 and the fact that air velocity is equal at orbital speed.
Hydrodynamic simulations have clearly shown that the flow structure of the AGB star with loss of mass in a wide binary system is very different from the simple and symmetrical body: hoyl accretion flow, with the presence of a large spiral 31-32.
Such a spiral has since been observed by the Hubble Space Telescope at Carbon Star AFGL 306833,34 and with the Atacama Large Millimeter / Submillimeter Array (ALMA) at R Scl35, and in some cases to determine binary output parameters. It has been used to .
The anterior spiral structure & once the AGB has developed into the white dwarf phase and a PN emerges, one can expect to manifestly emerge from the nebula. Therefore, some PNs would also be expected to have long-term binaries.
Observational evidence of the importance of binaries. The first confirmed binary central star, YU Sagethe, the central star of Abell 63, was found in 1976 comparing the General Catalog of the Galactic Planetary Nebula and the Catalog of Stars.
Subsequent observations have shown that Abel 63 is somewhat of an archaic system, displaying many of the characteristics that are now considered characteristics of the development of a binary star (Fig. 2).
The Abell 63 nebula was discovered to consist of a central barrel-shaped structure 43, in which the axis of symmetry is perpendicular to the binary orbital plane (as predicted), an extended high-speed outflow that occurs a few thousand years before the central.
Nebula 44. Furthermore, nebular layers have been shown to exhibit large discrepancies in the relative abundance of chemical species, depending on whether they are calculated using matching bright excited lines or weak recombination lines.
This much-discussed problem is present in almost all astrological nebulae, for which the ratio of abundance from recombination lines to lines excised by collision is on the order of 1-3 (Refs. 45,46). However, in Abel 63 the abundance discrepancy factor (ADF) is around 10 (Ref. 47).
Since 1976, many more PNs have been discovered with binary central stars, a large number of which show remarkable properties similar to those of Abel 63 and its central binary star YU Sagethe-48-51. The largest jump in the known number of adjacent binary stars comes from the Optical Gravitational Coating Experiment (OGLE) study.
A photometric study designed primarily to investigate dark matter using gravitational microlensing phenomena. Fortunately, the OGLE regions contained a series of PNs, for which the rate and sensitivity of the observations allowed their central stars to be examined to determine photometric variability 52.
This work doubled the number of binary central stars known at the time (adding systems20 new systems), allowing comparison of the general PN population with host nebulae. PNEs with detectable nearby binary stars were found to exhibit bipolar morphology with equatorial rings and extended jet characteristics.
As well as low ionization filament structures (Fig. 1) 53. Since then, these morphological characteristics have been used, with great success. , as former survey selectors specific to Central Star Binarity 54–59.
In addition to increasing the sample of known binaries, the OGLE survey provided the lowest skewed measurement of the photometrically detectable binary fraction to date. Only compatible with the core star systems seen by the survey.
Which is brighter than in20 magazine in band I and without significant nebular contamination, such binaries have a photometrically detectable sensor. Binary passages represent. It is important to note that this number represents a low threshold for the correct binary fraction.
The smallest radiation effect found as part of the OGLE sample is an amplitude of ir0.02 mag. However, the corresponding system also shows receptacles that are around 0.5 mag, making it very easy to detect variability. Except for systems that exhibit low-level radiation effects but are easily detectable.
The smallest amplitude radiation effects identified as part of the survey are all .10.1 mag. The amplitude of an observed radiation effect is a function of several parameters, including the temperature and brightness of the primary, the temperature and light of the secondary, and the binary period and tilt.
Figure 3 shows the amplitude of the radiation effect for a hypothetical ‘base’ system (such as that used by the next-generation Wilson-Davineni code, PHOEBE60) of a 100,000K hot central star (with other track-based parameters evolutionary 61) 1 day.
In the binary system of duration and inclination of 70 °. Each graph changes a parameter of the binary system, such as the duration / separation, inclination or spectral type (and, therefore, mass, temperature and lightness) of the secondary.
It is important to note that the second generation of post-EC binary central stars generally inflates with respect to the expected radius for a typical main sequence star of the same spectral type 59.
This would serve to increase the amplitude of the observed radiation effect, thus obtaining the results of a given spectral type as expected for a star, perhaps two or three spectral subtypes earlier (i.e. the observed radiation effect for a secondary M8V may.
In fact, be more in line with the prediction of the secondary M5V). It is clear that in shorter periods or higher slopes, or for a more massive second, the detection limit of 0.1 mag should result in approximately -100% integrity.
However, for longer periods (beyond 5 to 10 days) and, in particular, for less massive pairs (even if the inflated secondary is easier to detect), the integrity would be drastically reduced. We have discussed the integrity of a survey, such as the OGLE survey.
Which has a minimum detection amplitude of approximately 0.1 mag. Targeted observations can reach very low amplitudes (perhaps at least 0.01 mag) at the cost of observing very small samples. The discovery is particularly interesting in this regard, using the short-lived Kepler satellite, with variability at a 0.7 mmg binary post-EC level.
In this case, not due to a radiation effect, but to a combination of emission Doppler due to the tidal distortion of the two cables, also below the detection threshold from the ground 63, with specific observations. More importantly, in five central PN stars with usable Kepler data, four showed variability.
Which can be detected from the ground and this variability possibly related to forecasting. (Interestingly, none of the samples exhibited radiation effects.) This is clearly a small number of figures, but it is clear that the fraction of 20% may need an upward revision.
In any case, even the current fraction is very large, which can be explained by current models, such as the red giant branch and the magnitudes of stars such as the Sun at AGB64.65 and the tidal radius of giant stars. If the above is true, it may mean that not only do binaries shape PNs.
But there may also be a condition for making the most of them. Furthermore, it should not be forgotten that the CE phase can also lead to the fusion of the two components 66, thus increasing the fraction of early binary stars.
For these close binaries, PNs should also add the possibility of achieving larger binaries. A small group of PNs are known to harbor binary central stars enriched by a subgroup or massive companion carbon and elements of slow neutron capture process (S-process) 67-69.
These PNEs have a pronounced ring-like morphology, which is likely the result of a case of large-scale transfer, perhaps from air, leading to contamination of cold secondary stars in carbon elements and the S process.
Interestingly, long-term radial velocity monitoring provided the first confirmation of long-term binary motion in PN, with arrest at BD + 33 ° 2642, LTTR5, and NGC 15143.72. In fact, the duration of NGC 1514 is so long that previous long-term monitoring efforts (1-year monitoring) failed to recover any variability.
Extreme long-term monitoring over a period of approximately ten years was required to correct its periodicity, thus highlighting the difficulty of estimating the true binary fraction. Other surveys that, in theory, should be sensitive to longer durations and smaller pairs report binary fractions of more than 20%.
But generally 73.74 with smaller number numbers and more uncertainties. For example, the discovery of cool pairs based on their contribution to the spectral energy distribution of the central stellar spectrum (spectral excess), and the binary fraction of% 80%.
Which explains both the detection limit and the possible contribution of pairs white dwarfs. Results (with significant uncertainties), corresponding to the observed fraction of spherical PNe75. If this concludes, it would mean that dualism is almost a necessity to produce the planetary nebula 76.
A great effort has been made to characterize the known population of binary central stars and their host Niharika. For binary central stars, this requires gradual modeling of light and radial velocity. In many cases, the acute radiation effect leads to the production of emission lines on the secondary ‘face’ of the day side.
Although the primary is much brighter than the secondary in almost all bands, radial velocity curves can be derived from both components (for example, normal II, NV, and OV emission lines from primary and secondary absorption lines secondary to emission lines C III., C IV and N III).
This leads to a model independent measurement of mass relationships, which strongly inhibits subsequent modeling. Surprisingly, for Eu Sagethe, the secondary main sequence is highly inflated on all systems, subject to detailed modeling59.
In general, this inflation is considered to be an effect of the transfer of mass from primary to secondary, either during the EC or, very probably, just before. The mass transfer rate required to produce such a high level of inflation must be significant.
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