thick disk

It was shown that there is a diversity of thick disc formation scenarios.

{{cite journal

|last=Kasparova |first=A.

|year=2016

|title=The Diversity of Thick Galactic Discs

|journal=Monthly Notices of the Royal Astronomical Society: Letters

|volume=460 |issue=1 |pages=89–93

|arxiv=1604.07624

|bibcode=2016MNRAS.460L..89K

|doi=10.1093/mnrasl/slw083

|doi-access=free

}} In general, various scenarios for the formation of this structure have been proposed, including:

• Thick disks come from the heating of the thin disk{{Cite journal|last1=Villalobos|first1=Álvaro|last2=Helmi|first2=Amina|date=2008-12-01|title=Simulations of minor mergers - I. General properties of thick discs|journal=Monthly Notices of the Royal Astronomical Society|volume=391|issue=4|pages=1806–1827|doi=10.1111/j.1365-2966.2008.13979.x|doi-access=free |issn=0035-8711|bibcode = 2008MNRAS.391.1806V |arxiv=0803.2323|s2cid=14881474}}

{{cite journal

|last=Steinmetz |first=M.

|year=2012

|title=The Galactic thin and thick disk

|journal=Astronomische Nachrichten

|volume=333 |issue=5–6 |pages=523–529

|arxiv=1205.6098

|bibcode=2012AN....333..523S

|doi=10.1002/asna.201211698

|s2cid=119112515

}}

• It is a result of a merger event between the Milky Way and a massive dwarf galaxy
• More energetic stars migrate outwards from the inner galaxy to form a thick disk at larger radii

{{cite journal

|last1=Schoenrich |first1=R.

|last2=Binney |first2=J.

|year=2009

|title=Chemical Evolution with Radial Migration

|url=http://mnras.oxfordjournals.org/content/396/1/203.full.pdf

|journal=Monthly Notices of the Royal Astronomical Society

|volume=396 |issue=1 |pages=203–222

|arxiv=0809.3006

|bibcode=2009MNRAS.396..203S

|doi=10.1111/j.1365-2966.2009.14750.x

|doi-access=free

|s2cid=14749516

}}

{{cite journal

|last1=Loebman |first1=S.

|display-authors=etal

|year=2011

|title=The Genesis of the Milky Way's Thick Disk via Stellar Migration

|journal=The Astrophysical Journal

|volume=737 |issue=1 |pages=8

|arxiv=1009.5997

|bibcode=2011ApJ...737....8L

|doi=10.1088/0004-637X/737/1/8

|s2cid=21097464

}}

• The disk forms thick at high redshift with the thin disk forming later{{cite journal|last2=Kawata|first2=D.|last3=Gibson|first3=B. K.|last4=Freeman|first4=K. C.|year=2004|title=The Emergence of the Thick Disk in a CDM Universe|journal=The Astrophysical Journal|volume=612|issue=2|pages=894–899|arxiv=astro-ph/0405306|bibcode=2004ApJ...612..894B|doi=10.1086/422709|last1=Brook|first1=C. B|s2cid=54633942}}{{Cite journal|last1=Bournaud|first1=Frédéric|last2=Elmegreen|first2=Bruce G.|last3=Martig|first3=Marie|date=2009-12-01|title=The Thick Disks of Spiral Galaxies as Relics from Gas-rich, Turbulent, Clumpy Disks at High Redshift|journal=The Astrophysical Journal Letters|volume=707|issue=1|pages=L1–L5|doi=10.1088/0004-637X/707/1/L1|issn=0004-637X|arxiv = 0910.3677 |bibcode = 2009ApJ...707L...1B |s2cid=118528894}}
• Disk flaring combined with inside-out disk formation{{Cite journal|last1=Minchev|first1=I.|last2=Martig|first2=M.|last3=Streich|first3=D.|last4=Scannapieco|first4=C.|last5=de Jong|first5=R. S.|last6=Steinmetz|first6=M.|date=2015-04-24|title=On the Formation of Galactic Thick Disks|journal=The Astrophysical Journal|volume=804|issue=1|pages=L9|doi=10.1088/2041-8205/804/1/L9|issn=2041-8213|arxiv = 1502.06606 |bibcode = 2015ApJ...804L...9M |s2cid=59389858}}

{{cite web

|last1=Fohlmeister |first1=J.

|date=24 April 2015

|title=The riddle of galactic thin–thick disk solved

|url=http://phys.org/news/2015-04-riddle-galactic-thinthick-disk.html

|work=Phys.org

|access-date=24 May 2015

}}

• Scattering by massive clumps: stars born in massive gas clumps tend to be scattered to a thick disc and to be enriched in alpha-elements, while those formed out of these clumps form a thin disc and are alpha-poor{{Cite journal|last1=Bournaud|first1=Frédéric|last2=Elmegreen|first2=Bruce G.|last3=Martig|first3=Marie|date=2009-12-01|title=The Thick Disks of Spiral Galaxies as Relics from Gas-rich, Turbulent, Clumpy Disks at High Redshift|journal=The Astrophysical Journal Letters|volume=707|issue=1|pages=L1–L5|doi=10.1088/0004-637X/707/1/L1|issn=0004-637X|arxiv = 0910.3677 |bibcode = 2009ApJ...707L...1B |s2cid=118528894}}{{Cite journal|last1=Clarke|first1=A.|last2=Debattista|first2=V. P.|last3=Nidever|first3=D.|date=2019-04-01|title=The imprint of clump formation at high redshift - I. A disc alpha-abundance dichotomy|journal=Monthly Notices of the Royal Astronomical Society|volume=484|issue=3|pages=3476–3490|doi=10.1093/mnras/stz104|doi-access=free |issn=0004-637X|arxiv = 1901.00931 |bibcode = 2019MNRAS.484.3476C}}{{Cite journal|last1=Beraldo e Silva|first1=L.|last2=Debattista|first2=V. P.|last3=Khachaturyants|first3=T.|date=2020-03-01|title=Geometric properties of galactic discs with clumpy episodes|journal=Monthly Notices of the Royal Astronomical Society|volume=492|issue=4|pages=4716–4726|doi= 10.1093/mnras/staa065|doi-access=free |issn=0004-637X|arxiv = 1911.03717 |bibcode = 2020MNRAS.492.4716B}}

Although the thick disk is mentioned as a bona fide galactic structure in numerous scientific studies and it's even thought to be a common component of disk galaxies in general,

{{cite journal

|last1=Yoachim |first1=P.

|last2=Dalcanton |first2=J.

|year=2012

|title=Structural Parameters of Thin and Thick Disks in Edge-On Disk Galaxies

|journal=The Astronomical Journal

|volume=131 |issue=1 |pages=226–249

|arxiv=astro-ph/0508460

|bibcode=2006AJ....131..226Y

|doi=10.1086/497970

|s2cid=2219155

}} its nature is still under dispute.

The view of the thick disk as a single separate component has been questioned by a series of papers that describe the galactic disk with a continuous spectrum of components with different thicknesses.{{Cite journal|last1=Bovy|first1=Jo|last2=Rix|first2=Hans-Walter|last3=Liu|first3=Chao|last4=Hogg|first4=David W.|last5=Beers|first5=Timothy C.|last6=Lee|first6=Young Sun|date=2012-07-01|title=The Spatial Structure of Mono-abundance Sub-populations of the Milky Way Disk|journal=The Astrophysical Journal|volume=753|issue=2|pages=148|doi=10.1088/0004-637X/753/2/148|issn=0004-637X|arxiv = 1111.1724 |bibcode = 2012ApJ...753..148B |s2cid=118530729}}

{{cite journal

|last1=Bovy |first1=J.

|last2=Rix |first2=H.- W.

|last3=Hogg |first3=D. W.

|year=2012

|title=The Milky Way Has No Distinct Thick Disk

|journal=The Astrophysical Journal

|volume=751 |issue=2 |pages=131

|arxiv=1111.6585

|bibcode=2012ApJ...751..131B

|doi=10.1088/0004-637X/751/2/131

|s2cid=119299930

}}

• Disk galaxy
• Galactic coordinate system
• Galaxy formation and evolution

; Galaxy parts

• Galactic bulge
• Galactic halo
• Spiral arm
• Thin disk

{{Reflist}}

• [https://arxiv.org/abs/astro-ph/0310326 Thin and Thick Galactic Disks]
• [https://arxiv.org/abs/1108.5028 Structure and Evolution of the Milky Way]
• [http://www.ifa.hawaii.edu/~barnes/ast626_95/pcmw.html Populations & Components of the Milky Way]

{{Galaxy}}

Category:Galaxies