TW Hydrae

{{Starbox begin

| name = TW Hydrae

}}

{{Starbox image

| image = 250px

| caption = Inner region of TW Hydrae protoplanetary disc

| credit = S. Andrews, B. Saxton, ALMA (see description)

}}

{{Starbox observe

| epoch = J2000.0

| constell = Hydra

| ra = {{RA|11|01|51.9054}}

| dec = {{DEC|−34|42|17.0316}}>

| appmag_v = {{nowrap|11.27 ± 0.09}}

}}

{{Starbox character

| type = Pre-main-sequence

| class = K6

| r-i =

| v-r =

| b-v = 0.67

| u-b = -0.33

| j-h = 0.659

| j-k = 0.92

| variable = T Tauri

}}

{{Starbox astrometry

| radial_v = {{nowrap|13.40 ± 0.8}}

| prop_mo_ra = −68.389 ± 0.054

| prop_mo_dec = −14.016 ± 0.059

| parallax = 16.6428

| p_error = 0.0416

| parallax_footnote =

}}

{{Starbox detail

| age_myr = 8

| metal =

| mass = 0.8

| radius = 1.11

| gravity=

| rotation =

| luminosity_bolometric=0.28From $\begin{smallmatrix}L=4 \pi R^2 \sigma T_{\rm eff}^4 \end{smallmatrix}$ , where $\begin{smallmatrix}L \end{smallmatrix}$ is the luminosity, $\begin{smallmatrix}R \end{smallmatrix}$ is the radius, $\begin{smallmatrix}T_{\rm eff}\end{smallmatrix}$ is the effective surface temperature and $\begin{smallmatrix}\sigma \end{smallmatrix}$ is the Stefan–Boltzmann constant.

| temperature = 4,000

}}

{{Starbox catalog

| names = {{odlist|name=TWA 1|CD=−34° 7151|HIP=53911|V=TW Hya}}

}}

{{Starbox reference

| Simbad = TW+Hya

}}

TW Hydrae is a T Tauri star approximately 196 light-years away in the constellation of Hydra (the Sea Serpent). TW Hydrae is about 80% of the mass of the Sun, but is only about 5-10 million years old. The star appears to be accreting from a protoplanetary disk of dust and gas, oriented face-on to Earth, which has been resolved in images from the ALMA observatory. TW Hydrae is accompanied by about twenty other low-mass stars with similar ages and spatial motions, comprising the "TW Hydrae association" or TWA, one of the closest regions of recent "fossil" star-formation to the Sun.

Stellar characteristics

File:TWHyaLightCurve.png plotted from MOST microsatellite data published by Rucinski et al. (2008)]]

TW Hydrae is a pre-main-sequence star that is approximately 80% the mass of and 111% the radius of the Sun. It has a temperature of 4000 K and is about 8 million years old. In comparison, the Sun is about 4.6 billion years old{{cite web |url=http://www.universetoday.com/18237/how-old-is-the-sun/ |title=How Old is the Sun? |author=Fraser Cain |date=16 September 2008 |publisher=Universe Today |access-date=19 February 2011}} and has a temperature of 5778 K.{{cite web |url=http://www.universetoday.com/18092/temperature-of-the-sun/ |title=Temperature of the Sun |author=Fraser Cain |date=15 September 2008 |publisher=Universe Today |access-date=19 February 2011}} The star's luminosity is 28% (0.28x) that of the Sun, equivalent to that of a main-sequence star of spectral type ~K2. However, the spectral class is K6.

The star's apparent magnitude, or how bright it appears from Earth's perspective, is 11.27. It is too dim to be seen with the naked eye.

Planetary system

{{OrbitboxPlanet begin

| name = TW Hydrae

| table_ref={{cite journal|arxiv=1605.00289|last1=Tsukagoshi|first1=Takashi|title=A Gap with a Deficit of Large Grains in the protoplanetary disk around TW Hya|last2=Nomura|first2=Hideko|last3=Muto|first3=Takayuki|last4=Kawabe|first4=Ryohei|last5=Ishimoto|first5=Daiki|last6= Kanagawa|first6=Kazuhiro D.|last7=Okuzumi|first7=Satoshi|last8=Ida|first8=Shigeru|last9=Walsh|first9=Catherine|last10= Millar|first10=Tom J.|year=2016|doi=10.3847/2041-8205/829/2/L35|volume=829|journal=The Astrophysical Journal|issue=2|page=L35|bibcode = 2016ApJ...829L..35T |s2cid=41738556 |doi-access=free }}

}}

{{OrbitboxPlanet hypothetical

| exoplanet = b

| mass_earth = 23.72

| period =

| semimajor = 22

| radius_earth = ~4.25

| inclination =

}}

{{OrbitboxPlanet hypothetical

| exoplanet = c

| mass_earth = 4

| period =

| semimajor = 42

| radius_earth =

| inclination =

}}

{{OrbitboxPlanet disk

| disk = Protoplanetary disk

| periapsis = 1

| apoapsis = 30?

| inclination =

}}

The star is known to host one likely exoplanet, TW Hydrae b.

=Protoplanetary disk=

==Previously disproven protoplanet==

In December 2007, a team led by Johny Setiawan of the Max Planck Institute for Astronomy in Heidelberg, Germany announced discovery of a planet orbiting TW Hydrae, dubbed "TW Hydrae b" with a minimum mass around 1.2 Jupiter masses, a period of 3.56 days, and an orbital radius of 0.04 astronomical units (inside the inner rim of the protoplanetary disk). Assuming it orbits in the same plane as the outer part of the dust disk (inclination 7±1°), it has a true mass of 9.8±3.3 Jupiter masses. However, if the inclination is similar to the inner part of the dust disk (4.3±1.0°), the mass would be 16{{±|5|3}} Jupiter masses, making it a brown dwarf. Since the star itself is so young, it was presumed this is the youngest extrasolar planet yet discovered, and essentially still in formation.

In 2008 a team of Spanish researchers concluded that the planet does not exist: the radial velocity variations were not consistent when observed at different wavelengths, which would not occur if the origin of the radial velocity variations was caused by an orbiting planet. Instead, the data was better modelled by starspots on TW Hydrae's surface passing in and out of view as the star rotates. "Results support the spot scenario rather than the presence of a hot Jupiter around TW Hya". Similar wavelength-dependent radial velocity variations, also caused by starspots, have been detected on other T Tauri stars.

==New study of more distant planet==

In 2016, ALMA found evidence that a possible Neptune-like planet was forming in its disk, at a distance of around 22 AU.{{Cite web|url=https://www.independent.co.uk/news/science/giant-planet-born-in-stars-dust-cloud-tw-hydrae-a7307931.html |archive-url=https://ghostarchive.org/archive/20220526/https://www.independent.co.uk/news/science/giant-planet-born-in-stars-dust-cloud-tw-hydrae-a7307931.html |archive-date=2022-05-26 |url-access=subscription |url-status=live|title = Astronomers discover signs of planet being born around a star|website=Independent.co.uk |date = 14 September 2016}}

== Outflow of an embedded protoplanet ==

In 2024 observations with ALMA showed sulfur monoxide representing an outflow from an embedded protoplanet. The position of the brightest emission coincides with a planet-carved dust gap at 42 au. Previously this gap was associated with the formation of a super-earth and modelling of the outflow velocity, the researchers estimate a mass of about 4 earth-masses. The mass accretion of this embedded protoplanet is constrained to between 3 x10⁻⁷ and 10⁻⁵ {{Jupiter mass|link=true}}/year.

==Detection of methanol==

In 2016, methanol, one of the building blocks for life, was detected in the star's protoplanetary disk.{{Cite web|url=http://www.space.com/33193-organic-molecule-planet-forming-disk.html|title = Methanol, a Building Block of Life, Found Around Newborn Star for 1st Time| website=Space.com | date=17 June 2016 }}{{Cite web|last=Astrophysics|first=Harvard-Smithsonian Center for|date=2016-06-20|title=ALMA Reveals Methanol in the TW Hydrae Protoplanetary Disk|url=https://scitechdaily.com/alma-reveals-methanol-in-the-tw-hydrae-protoplanetary-disk/|access-date=2021-08-06|website=SciTechDaily|language=en-US}}{{Cite web|title=Methanol Detected in Protoplanetary Disc around Young Star TW Hydrae {{!}} Astronomy {{!}} Sci-News.com|url=http://www.sci-news.com/astronomy/methanol-protoplanetary-disc-tw-hydrae-03952.html|access-date=2021-08-06|website=Breaking Science News {{!}} Sci-News.com|date=15 June 2016 |language=en-US}}{{Cite web|title=NASA Astrobiology|url=https://astrobiology.nasa.gov/news/methanol-detected-for-first-time-around-young-star/|access-date=2021-08-06|website=astrobiology.nasa.gov|language=en-EN}}{{Cite web|title=First Detection of Methyl Alcohol in a Planet-forming Disk|url=https://public.nrao.edu/news/2016-methanol-alma/|access-date=2021-08-06|website=National Radio Astronomy Observatory|language=en-US}}{{Cite web|last=Dockrill|first=Peter|title=Scientists Just Discovered Methyl Alcohol in a Nearby Planet-Forming Disc|url=https://www.sciencealert.com/scientists-just-discovered-methyl-alcohol-in-a-nearby-planet-forming-disc|access-date=2021-08-06|website=ScienceAlert|date=16 June 2016 |language=en-gb}}{{Cite web|last=Report|first=Science World|date=2017-05-29|title=Methanol Discovered For The First Time In The Protoplanetary Disk Of Young Star 'TW Hydra'|url=https://www.scienceworldreport.com/articles/59704/20170529/methanol-discovered-first-time-protoplanetary-disk-young-star-tw-hydra.htm|access-date=2021-08-06|website=Science World Report|language=en-US}}{{Cite web|title=A Molecule For Life Has Been Found Inside A Nearby Planetary Nursery|url=https://www.ndtv.com/world-news/a-molecule-for-life-has-been-found-inside-a-nearby-planetary-nursery-1419940|access-date=2021-08-06|website=NDTV.com}}

Gallery

{{Gallery |align=center |width=250

|File:Shadow on TW Hydrae’s disc.jpg|{{center|{{small|Shadow moving counterclockwise around a gas and dust disc.{{cite web|title=Shadow on TW Hydrae's disc|url=https://www.spacetelescope.org/images/opo1703a/|website=www.spacetelescope.org|access-date=12 January 2017}}}}}}

|File:Hubble Uncovers Evidence of Farthest Planet Forming From its Star.jpg|{{center|{{small|Simulation based on Hubble observations.}}}}

|File:TW Hydrae protoplanetary disc.jpg|{{center|{{small|TW Hydrae protoplanetary disc.}}}}

|File:Concentric gas and dust discs around the star TW Hydrae (heic2305a).jpg|{{center|{{small|This illustration is based on NASA/ESA Hubble Space Telescope images of a gas and dust discs encircling the young star TW Hydrae.}}}}

|File:Artist’s impression of the disc around the young star TW Hydrae.webm|{{center|{{small|This artist’s impression video shows the protoplanetary disc around TW Hydrae. The organic molecule methyl alcohol (methanol) has been found in this disc.}}}}

}}

Notes

References

{{reflist|refs=

{{Cite journal |last1=Yoshida |first1=Tomohiro C. |last2=Nomura |first2=Hideko |last3=Law |first3=Charles J. |last4=Teague |first4=Richard |last5=Shibaike |first5=Yuhito |last6=Furuya |first6=Kenji |last7=Tsukagoshi |first7=Takashi |date=2024-08-01 |title=Outflow Driven by a Protoplanet Embedded in the TW Hya Disk |journal=The Astrophysical Journal |volume=971 |issue=1 |pages=L15 |arxiv=2407.14395 |bibcode=2024ApJ...971L..15Y |doi=10.3847/2041-8213/ad654c |doi-access=free |issn=0004-637X}}

{{cite journal |last1=Rucinski |first1=Slavek M. |last2=Matthews |first2=Jaymie M. |last3=Kuschnig |first3=Rainer |last4=Pojmanski |first4=Grzegorz |last5=Rowe |first5=Jason |last6=Guenther |first6=David B. |last7=Moffat |first7=Anthony F. J. |last8=Sasselov |first8=Dimitar |last9=Walker |first9=Gordon A. H. |last10=Weiss |first10=Werner W. |title=Photometric variability of the T Tauri star TW Hya on time-scales of hours to years |journal=Monthly Notices of the Royal Astronomical Society |date=December 2008 |volume=391 |issue=4 |pages=1913–1924 |doi=10.1111/j.1365-2966.2008.14014.x |arxiv=0809.3987 |bibcode=2008MNRAS.391.1913R |doi-access=free }}

{{cite journal|author=Prato, L.|display-authors=etal|title=A Young Planet Search in Visible and IR Light: DN Tau, V836 Tau, and V827 Tau|date=2008|journal=The Astrophysical Journal|volume=687|issue=2|pages=L103–L106|doi=10.1086/593201|bibcode=2008ApJ...687L.103P|arxiv = 0809.3599 |s2cid=14888302}}

{{cite journal|author=Huelamo, N.|display-authors=etal|title=TW Hydrae: evidence of stellar spots instead of a Hot Jupiter|journal=Astronomy and Astrophysics|volume=489|issue=2|pages=L9–L13|date=2008|doi=10.1051/0004-6361:200810596|bibcode=2008A&A...489L...9H|arxiv = 0808.2386 |s2cid=18775872}}

{{cite web|url=http://www.mpia.de/Public/menu_q2e.php?Aktuelles/PR/2008/PR080103/PR_080103_en.html|title=A young extrasolar planet in its cosmic nursery: Astronomers from Heidelberg discover planet in a dusty disk around a newborn star|date=2008-01-02|publisher=Max Planck Institute for Astronomy|access-date=2008-01-03}}

{{cite journal|title=Spectro-astrometric imaging of molecular gas within protoplanetary disk gaps|author=Pontoppidan, Klaus M.|display-authors=etal|date=2008|journal=The Astrophysical Journal|volume=684|issue=2|pages=1323–1329|doi=10.1086/590400|bibcode=2008ApJ...684.1323P|arxiv = 0805.3314 |s2cid=15445587}}

{{cite news| url=https://www.newscientist.com/article/dn13135-first-planet-discovered-around-a-youthful-star.html | title=First planet discovered around a youthful star| date=2 January 2008| publisher= NewScientist.com news service| first= Maggie| last= McKee| access-date=2008-01-02}}

{{cite journal|journal=Nature|volume= 451|pages= 38–41|date=3 January 2008| doi=10.1038/nature06426| title=A young massive planet in a star–disk system

| first1=J.| last1= Setiawan

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{{citation | first1=J.H. | last1=Rhee | first2=I. | last2=Song | first3=B. | last3=Zuckerman | first4=M. | last4=McElwain |date=May 2007 | title=Characterization of dusty debris disks: the IRAS and Hipparcos catalogs | display-authors=1 | journal=The Astrophysical Journal | volume=660 | issue=2 | pages=1556–1571 | bibcode=2007ApJ...660.1556R | doi=10.1086/509912 | postscript=. |arxiv = astro-ph/0609555| s2cid=11879505 }}[http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ52c4e54377c1&-out.add=.&-source=J/ApJ/660/1556/table2&recno=72 Vizier catalog entry]

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{{cite journal | first1=Qi | last1=Chunhua | first2=Karin I. | last2=Öberg | first3=David J. | last3=Wilner | first4=Paola| last4=D'Alessio | first5=Edwin | last5=Bergin | first6=Sean M. | last6= Andrews | first7=Geoffrey A. | last7=Blake | first8=Michiel R. | last8=Hogerheijde | first9=Ewine F. | last9=van Dishoeck |date=August 2013 | title=Imaging of the CO Snow Line in a Solar Nebula Analog | display-authors=1 | journal=Science | volume=341 | issue=6146 | pages=630–632 | bibcode=2013Sci...341..630Q | doi=10.1126/science.1239560 |arxiv = 1307.7439 | pmid=23868917| s2cid=23271440 }}

}}

External links

{{cite web |url=http://www.spacetelescope.org/news/html/heic0501.html |title=Hubble's infrared eyes home in on suspected extrasolar planet |access-date=2008-06-24 |work=NASA |publisher=Hubble Space Telescope}}
{{cite encyclopedia |url=https://exoplanet.eu/catalog/tw_hya_b--448/ |encyclopedia=Extrasolar Planets Encyclopaedia |title=Notes for star TW Hya and possible planet TW Hya b |access-date=2014-01-06 }}

Category:Hydra (constellation)

Category:K-type main-sequence stars

Category:T Tauri stars

Category:Circumstellar disks

Category:TW Hydrae association

Hydrae, TW

Category:Durchmusterung objects

053911

Category:Hypothetical planetary systems