Protoplanetary nebula

Short description: Nebula surrounding a dying star

File:Westbrook Nebula.tif

A protoplanetary nebula or preplanetary nebula (Sahai Sánchez Contreras) (PPN, plural PPNe) is an astronomical object which is at the short-lived episode during a star's rapid evolution between the late asymptotic giant branch (LAGB)[a] phase and the subsequent planetary nebula (PN) phase. A PPN emits strongly in infrared radiation, and is a kind of reflection nebula. It is the second-from-the-last high-luminosity evolution phase in the life cycle of intermediate-mass stars (1–8 M☉). (Kastner 2005)

## Contents

* 1 Naming
* 2 Evolution
* 2.1 Beginning
* 2.2 Protoplanetary nebula phase
* 2.3 End
* 3 Recent conjectures
* 4 See also
* 5 Notes
* 6 References

## Naming

File:IRAS 13208-6020.tif

The name protoplanetary nebula is an unfortunate choice due to the possibility of confusion with the same term being sometimes employed when discussing the unrelated concept of protoplanetary disks. The name protoplanetary nebula is a consequence of the older term planetary nebula, which was chosen due to early astronomers looking through telescopes and finding a similarity in appearance of planetary nebula to the gas giants such as Neptune and Uranus. To avoid any possible confusion, Sahai, Sánchez Contreras & Morris 2005 suggested employing a new term preplanetary nebula which does not overlap with any other disciplines of astronomy. They are often referred to as post-AGB stars, although that category also includes stars that will never ionize their ejected matter.

## Evolution

### Beginning

During the late asymptotic giant branch (LAGB)[a] phase, when mass loss reduces the hydrogen envelope's mass to around 10−2 M☉ for a core mass of 0.60 M☉, a star will begin to evolve towards the blue side of the Hertzsprung–Russell diagram. When the hydrogen envelope has been further reduced to around 10−3 M☉, the envelope will have been so disrupted that it is believed further significant mass loss is not possible. At this point, the effective temperature of the star, T*, will be around 5,000 K and it is defined to be the end of the LAGB and the beginning of the PPN. (Davis Smith)

### Protoplanetary nebula phase

Protoplanetary nebula known as IRAS 20068+4051 taken by Hubble's Advanced Camera for Surveys.

During the ensuing protoplanetary nebula phase, the central star's effective temperature will continue rising as a result of the envelope's mass loss as a consequence of the hydrogen shell's burning. During this phase, the central star is still too cool to ionize the slow-moving circumstellar shell ejected during the preceding AGB phase. However, the star does appear to drive high-velocity, collimated winds which shape and shock this shell, and almost certainly entrain slow-moving AGB ejecta to produce a fast molecular wind. Observations and high-resolution imaging studies from 1998 to 2001, demonstrate that the rapidly evolving PPN phase ultimately shapes the morphology of the subsequent PN. At a point during or soon after the AGB envelope detachment, the envelope shape changes from roughly spherically symmetric to axially symmetric. The resultant morphologies are bipolar, knotty jets and Herbig–Haro-like "bow shocks". These shapes appear even in relatively "young" PPNe. (Davis Smith)

### End

The PPN phase continues until the central star reaches around 30,000 K and it is hot enough (producing enough ultraviolet radiation) to ionize the circumstellar nebula (ejected gases) and it becomes a kind of emission nebula called a Planetary Nebula. This transition must take place in less than around 10,000 years or else the density of the circumstellar envelope will fall below the PN formulation density threshold of around 100[clarification needed] per cm³ and no PN will result, such a case is sometimes referred to as a 'lazy planetary nebula'. (Volk Kwok)

## Recent conjectures

An interstellar butterfly - protoplanetary nebula Roberts 22[1]

Bujarrabal et al. (2001) [2] found that the "interacting stellar winds" model of Kwok et al. (1978) [3] of radiatively-driven winds is insufficient to account for their CO observations of PPN fast winds which imply high momentum and energy inconsistent with that model. Complementarily, theorists (Soker & Livio 1994; [4] Reyes-Ruiz & Lopez 1999;[5] Soker & Rappaport 2000;[6] Blackman, Frank & Welch 2001[7]) investigated whether accretion disk scenarios, similar to models used to explain jets from active galactic nuclei and young stars, could account for both the point symmetry and the high degree of collimation seen in many PPN jets. In such models applied to the PPN context, the accretion disk forms through binary interactions. Magneto-centrifugal launching from the disk surface is then a way to convert gravitational energy into the kinetic energy of a fast wind in these systems.[7] If the accretion-disk jet paradigm is correct and magneto-hydrodynamics (MHD) processes mediate the energetics and collimation of PPN outflows, then they will also determine physics of the shocks in these flows, and this can be confirmed with high-resolution pictures of the emission regions that go with the shocks. (Davis Smith)

## See also

* Bipolar nebula
* Bipolar outflow
* List of protoplanetary nebulae
* Planetary nebula

## Notes

1. ^ The late asymptotic giant branch begins at the point on the asymptotic giant branch (AGB) where a star is no longer observable in visible light and becomes an infrared object. (Volk Kwok)

## References

1. ↑ "An interstellar butterfly". ESA / HUBBLE. http://www.spacetelescope.org/images/potw1410a/.
2. ↑ "Bujarrabal, V., Castro-Carrizo, A., Alcolea, J., S{\'a}nchez Contreras, C.; 2001.; Mass, linear momentum and kinetic energy of bipolar flows in protoplanetary nebulae.; Astronomy and Astrophysics 377, 868–897. doi:10.1051/0004-6361:20011090". https://ui.adsabs.harvard.edu/abs/2001A&A...377..868B;/abstract.
3. ↑ "Kwok, S., Purton, C.R., Fitzgerald, P.M.; 1978; On the origin of planetary nebulae; The Astrophysical Journal 219, L125–L127. doi:10.1086/182621". https://ui.adsabs.harvard.edu/abs/1978ApJ...219L.125K/abstract.
4. ↑ "Soker, N., Livio, M.; 1994; Disks and jets in planetary nebulae; The Astrophysical Journal 421, 219. doi:10.1086/173639". https://ui.adsabs.harvard.edu/abs/1994ApJ...421..219S/abstract.
5. ↑ "Reyes-Ruiz, M., López, J.A.; 1999; Accretion Disks in Pre-Planetary Nebulae; The Astrophysical Journal 524, 952–960. doi:10.1086/307827". https://ui.adsabs.harvard.edu/abs/1999ApJ...524..952R/abstract.
6. ↑ "Soker, N., Rappaport, S.; 2000; The Formation of Very Narrow Waist Bipolar Planetary Nebulae; The Astrophysical Journal 538, 241–259. doi:10.1086/309112". https://ui.adsabs.harvard.edu/abs/2000ApJ...538..241S/abstract.
7. ↑ 7.0 7.1 "Blackman, E.G., Frank, A., Welch, C.; 2001; Magnetohydrodynamic Stellar and Disk Winds: Application to Planetary Nebulae; The Astrophysical Journal 546, 288–298. doi:10.1086/318253". https://ui.adsabs.harvard.edu/abs/2001ApJ...546..288B/abstract.

* Davis, C. J.; Smith, M. D.; Gledhill, T. M.; Varricatt, W. P. (2005), "Near-infrared echelle spectroscopy of protoplanetary nebulae: probing the fast wind in H2", Monthly Notices of the Royal Astronomical Society 360 (1): 104–118, doi:10.1111/j.1365-2966.2005.09018.x, Bibcode: 2005MNRAS.360..104D .
* Kastner, J. H. (2005), "Near-death Transformation: Mass Ejection in Planetary Nebulae and Protoplanetary Nebulae", American Astronomical Society Meeting 206, #28.04; Bulletin of the American Astronomical Society 37: 469, Bibcode: 2005AAS...206.2804K .
* Sahai, Raghvendra; Sánchez Contreras, Carmen; Morris, Mark (2005), "A Starfish Preplanetary Nebula: IRAS 19024+0044", The Astrophysical Journal 620 (2): 948–960, doi:10.1086/426469, Bibcode: 2005ApJ...620..948S, https://trs.jpl.nasa.gov/bitstream/2014/40924/1/04-3294.pdf .
* Volk, Kevin M.; Kwok, Sun (July 1, 1989), "Evolution of protoplanetary nebulae", The Astrophysical Journal 342: 345–363, doi:10.1086/167597, Bibcode: 1989ApJ...342..345V .
* Szczerba, Ryszard; Siódmiak, Natasza; Stasińska, Grażyna; Borkowski, Jerzy (April 23, 2007), "An evolutive catalogue of Galactic post-AGB and related objects", Astronomy and Astrophysics 469 (2): 799–806, doi:10.1051/0004-6361:20067035, Bibcode: 2007A&A...469..799S, http://www.ncac.torun.pl/postagb?cat=confirmed&lang=en&branch=postagbworld&id=0&menuoff=1 .

* v
* t
* e

Stars

Formation|

* Accretion
* Molecular cloud
* Bok globule
* Young stellar object
* Protostar
* Pre-main-sequence
* Herbig Ae/Be
* T Tauri
* FU Orionis
* Herbig–Haro object
* Hayashi track
* Henyey track

Evolution|

* Main sequence
* Red-giant branch
* Horizontal branch
* Red clump
* Asymptotic giant branch
* Blue loop
* Protoplanetary nebula
* Planetary nebula
* PG1159
* Dredge-up
* Instability strip
* Luminous blue variable
* Blue straggler
* Stellar population
* Supernova
* Superluminous supernova / Hypernova

Spectral
classification|

* Early
* Late
* Main sequence
* O
* B
* A
* F
* G
* K
* M
* Brown dwarf
* WR
* OB
* Subdwarf
* O
* B
* Subgiant
* Giant
* Blue
* Red
* Yellow
* Bright giant
* Supergiant
* Blue
* Red
* Yellow
* Hypergiant
* Yellow
* Carbon
* S
* CN
* CH
* White dwarf
* Chemically peculiar
* Am
* Ap/Bp
* HgMn
* Helium-weak
* Barium
* Extreme helium
* Lambda Boötis
* Lead
* Technetium
* Be
* Shell
* B[e]

Remnants|

* White dwarf
* Helium planet
* Black dwarf
* Neutron
* Radio-quiet
* Pulsar
* Binary
* X-ray
* Magnetar
* Stellar black hole
* X-ray binary
* Burster

Hypothetical|

* Blue dwarf
* Green
* Black dwarf
* Exotic
* Boson
* Electroweak
* Strange
* Preon
* Planck
* Dark
* Dark-energy
* Quark
* Q
* Black
* Gravastar
* Frozen
* Quasi-star
* Thorne–Żytkow object
* Iron
* Blitzar

Stellar
nucleosynthesis|

* Deuterium burning
* Lithium burning
* Proton–proton chain
* CNO cycle
* Helium flash
* Triple-alpha process
* Alpha process
* Carbon burning
* Neon burning
* Oxygen burning
* Silicon burning
* S-process
* R-process
* Fusor
* Nova
* Symbiotic
* Remnant
* Luminous red nova

Structure|

* Core
* Convection zone
* Microturbulence
* Oscillations
* Radiation zone
* Atmosphere
* Photosphere
* Starspot
* Chromosphere
* Corona
* Stellar wind
* Bubble
* Bipolar outflow
* Accretion disk
* Asteroseismology
* Helioseismology
* Eddington luminosity
* Kelvin–Helmholtz mechanism

Properties|

* Designation
* Dynamics
* Effective temperature
* Luminosity
* Kinematics
* Magnetic field
* Absolute magnitude
* Mass
* Metallicity
* Rotation
* Starlight
* Variable
* Photometric system
* Color index
* Hertzsprung–Russell diagram
* Color–color diagram

Star systems|

* Binary
* Contact
* Common envelope
* Eclipsing
* Symbiotic
* Multiple
* Cluster
* Open
* Globular
* Super
* Planetary system

Earth-centric
observations|

* Sun
* Solar System
* Sunlight
* Pole star
* Circumpolar
* Constellation
* Asterism
* Magnitude
* Apparent
* Extinction
* Photographic
* Radial velocity
* Proper motion
* Parallax
* Photometric-standard

Lists|

* Proper names
* Arabic
* Chinese
* Extremes
* Most massive
* Highest temperature
* Largest volume
* Smallest volume
* Brightest
* Historical
* Most luminous
* Nearest
* Nearest bright
* With exoplanets
* Brown dwarfs
* White dwarfs
* Milky Way novae
* Supernovae
* Candidates
* Remnants
* Planetary nebulae
* Timeline of stellar astronomy

Related articles|

* Substellar object
* Brown dwarf
* Sub-brown dwarf
* Planet
* Galactic year
* Galaxy
* Guest
* Gravity
* Intergalactic
* Starfield
* Tidal disruption event

'Category:Stars * '

* v
* t
* e

Nebula

Visible nebula|

* Dark nebula
* Diffuse nebula
* Emission nebula
* Planetary nebula
* Supernova remnant
* Nova remnant
* H II region
* Reflection nebula
* Variable nebula
* Preplanetary nebula

Pre-stellar nebula|

* Giant molecular cloud
* Bok globule
* Evaporating gaseous globule
* Solar nebula

Stellar nebula|

* Nova remnant
* Protoplanetary nebula
* Wolf–Rayet nebula

Post-stellar nebula|

* Planetary nebula
* Supernova remnant
* Pulsar wind nebula
* Supershell

Clouds|

* Interstellar cloud
* Molecular cloud
* Infrared cirrus
* High-velocity cloud
* H I region

Morphology|

* Bipolar nebula
* Pinwheel nebula

Lists|

* Diffuse
* Planetary (PNe)
* Protoplanetary (PPNe)
* Supernova remnants (SNRs)

* Category
* Commons
* Wiktionary

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Protoplanetary nebula. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:Protoplanetary_nebula&oldid=2992501"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template