Astronomy:AWI0005x3s

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AWI0005x3s
Pretransitional disk 5x3s.png
Artist's Impression of AWI0005x3s
Credit: NASA's Goddard Space Flight Center/Jonathan Holden
Observation data
Equinox J2000.0]] (ICRS)
Constellation Carina
Right ascension  08h 08m 22.18s[1]
Declination −64° 43′ 57.3″[1]
Characteristics
Evolutionary stage red dwarf
Spectral type M5.5V[2]
Astrometry
Radial velocity (Rv)22.7 ± 0.5[1] km/s
Proper motion (μ) RA: −11.54±0.12[1] mas/yr
Dec.: 25.61±0.10[1] mas/yr
Parallax (π)9.8599±0.0551[3] mas
Distance331 ly
(101.4 ± 0.6[1] pc)
Details
Mass0.16+0.03
−0.04[1] M☉
Temperature3050 ± 100[1] K
Age45+11−7[4] Myr
Other designations
WISE J080822.18-644357.3
Database references
SIMBADdata

AWI0005x3s is a 45+11−7 Myr old [4] star system in the Carina constellation with a debris disk orbiting an M-type red dwarf about 331 lightyears from Earth.

On October 21, 2016, NASA's Goddard Space Flight Center announced that its citizen science project, Disk Detective, discovered a debris disk around WISE J080822.18-644357.3, a M5.5V dwarf with significant infrared excess at both 12 and 22 μm. Classified as DDOI AWI0005x3s, a BANYAN II Bayesian analysis revealed (with 93.9% probability) the star's radial velocity as 20.6 ± 1.4 km/s, associating it with Carina's ∼45 Myr old young moving group. Since most M dwarf debris disks fade in less than 30 million years, this would be the oldest M dwarf debris disk detected in a moving group, implying a change in understanding of constraint in M dwarf debris disk evolution.[5][2]

A follow-up study with an optical spectrum obtained with the ANU Siding Spring 2.3 meter telescope showed a Li-rich M5-star with strong Hα emission. The data is consistent with a low accretion of 10-10 M☉ yr -1.[6] ALMA observations did not detect any carbon monoxide, but unresolved 1.3 mm dust emission was detected.[1]

Debris Disk

The fitting of a modelled disk with the Spectral Energy Distribution of AWI0005x3s indicates a disk temperature of about 263 K (-10 °C or 14 °F).[2] The follow-up study found that a single disk had a poor match with the 22 μm data. The researchers found a better match with a "warm" outer disk with a temperature of about 240 K (-33 °C or -28 °F) and a "hot" inner disk with a temperature of about 1100 K (827 °C or 1520 °F). The warm outer disk is located around 0.115 au and the hot inner disk is located around 0.0056 au. The hot inner disk is likely the source of accreted material. The temperature of the inner disk is comparable to temperatures where amorphous silicates anneal into crystalline form. The inner disk also lies near the Roche limit of the red dwarf and therefore the inner disk could be the result of disrupted planetesimals. The warm outer disk could be similar to dust belts seen around B- to K-type stars, which have temperatures around 190 K and which likely represent small dust grains of sublimating ice from icy planetesimals.[6]

ALMA detected a third component with a temperature of 20 K (-253 °C or -424 °F). Using this temperature the researchers were able to estimate the dust mass to 0.057±0.006 M☉. This is higher than the disk mass around ~20 Myr old AU Microscopii and the ~50 Myr old GJ 182, but smaller than the ~10 Myr old TWA 7. The disk has a radius smaller than 16 au. The missing CO detection is explained with two possible scenarios: Either dust grains are released in a collisional cascade induced by the collisions of km-sized planetesimals or a recent collision of planetary bodies generated a large amount of small dust grains.[1]

Peter Pan Disks

There are other examples of low-mass stars and brown dwarfs that show accretion or circumstellar disks and were found in the GAYA (Great Austral Young Association, containing Carina, Columba, Tucana-Horologium[7]) complex. Examples are 2MASS J0041353-562112 in Tuc-Hor[8][9], 2MASS J05010082-4337102 in Columba and 2MASS J02265658-5327032 in Tuc-Hor.[10] The Tuc-Hor association has an age of 45±4 Myr and the Columba association has an age of 42+6−4 Myr. Together with AWI0005x3s these older low-mass accretors in nearby moving groups are being called Peter Pan Disks by the Disk Detective collaboration.[11]

Gallery

  • Spectral Energy Distribution (SED) of AWI0005x3s (disk detective talk)

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Flaherty, Kevin; Hughes, A. Meredith; Mamajek, Eric E.; Murphy, Simon J. (2019-02-13). "The Planet Formation Potential around a 45 Myr Old Accreting M Dwarf". The Astrophysical Journal 872 (1): 92. doi:10.3847/1538-4357/aaf794. ISSN 1538-4357. 
  2. ↑ 2.0 2.1 2.2 Silverberg, Steven M.; Kuchner, Marc J.; Wisniewski, John P.; Gagné, Jonathan; Bans, Alissa S.; Bhattacharjee, Shambo; Currie, Thayne R.; Debes, John R. et al. (14 October 2016). "A New M Dwarf Debris Disk Candidate in a Young Moving Group Discovered with Disk Detective" (in en). The Astrophysical Journal 830 (2): L28. doi:10.3847/2041-8205/830/2/L28. ISSN 2041-8205. 
  3. ↑ Gaia Collaboration (2018-08-01). "Gaia Data Release 2 - Summary of the contents and survey properties" (in en). Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. ISSN 0004-6361. https://www.aanda.org/articles/aa/abs/2018/08/aa33051-18/aa33051-18.html. 
  4. ↑ 4.0 4.1 Bell, Cameron P. M.; Mamajek, Eric E.; Naylor, Tim (2015-11-21). "A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood" (in en). Monthly Notices of the Royal Astronomical Society 454 (1): 593–614. doi:10.1093/mnras/stv1981. ISSN 0035-8711. https://academic.oup.com/mnras/article/454/1/593/1134330. 
  5. ↑ Ramsey, Sarah (2016-10-21). "Citizen Scientists Discover Potential New Exoplanet Hunting Ground". http://www.nasa.gov/press-release/nasa-citizen-scientists-discover-potential-new-hunting-ground-for-exoplanets. 
  6. ↑ 6.0 6.1 Murphy, Simon J.; Mamajek, Eric E.; Bell, Cameron P. M. (2018-05-21). "WISE J080822.18−644357.3 – a 45 Myr-old accreting M dwarf hosting a primordial disc" (in en). Monthly Notices of the Royal Astronomical Society 476 (3): 3290–3302. doi:10.1093/mnras/sty471. ISSN 0035-8711. 
  7. ↑ Torres, C.A.O.; Quast, G.R.; Melo, C.H.F.; Sterzik, M.F. (2008). "Young Nearby Loose Associations - aspmonographs.org". http://aspmonographs.org/custom/publications/paper/005-0757.html. 
  8. ↑ Reiners, Ansgar (21 August 2009). "Evidence for Accretion in a Nearby, Young Brown Dwarf" (in en). The Astrophysical Journal 702 (2): L119–L123. doi:10.1088/0004-637X/702/2/L119. ISSN 1538-4357. 
  9. ↑ Gagné, Jonathan; Lafrenière, David; Doyon, René; Malo, Lison; Artigau, Étienne (24 February 2014). "Banyan. Ii. Very Low Mass and Substellar Candidate Members to Nearby, Young Kinematic Groups with Previously Known Signs of Youth" (in en). The Astrophysical Journal 783 (2): 121. doi:10.1088/0004-637X/783/2/121. ISSN 0004-637X. 
  10. ↑ Boucher, Anne; Lafrenière, David; Gagné, Jonathan; Malo, Lison; Faherty, Jacqueline K.; Doyon, René; Chen, Christine H. (15 November 2016). "Banyan. Viii. New Low-Mass Stars and Brown Dwarfs with Candidate Circumstellar Disks" (in en). The Astrophysical Journal 832 (1): 50. doi:10.3847/0004-637X/832/1/50. ISSN 0004-637X. 
  11. ↑ "Low-mass Stars | Steven M. Silverberg". https://www.nhn.ou.edu/~smsilver/PeterPanDisks.html. 

External links





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