Chamaeleon complex explained

The Chamaeleon complex is a large star forming region (SFR) at the surface of the Local Bubble that includes the Chamaeleon I, Chamaeleon II, and Chamaeleon III dark clouds. It occupies nearly all of the constellation Chamaeleon and overlaps into Apus, Musca, Carina and Octans. The mean density of X-ray sources is about one source per square degree.[1]

Chamaeleon I dark cloud

The Chamaeleon I (Cha I) cloud is one of the nearest active star formation regions at ~160 pc. It is relatively isolated from other star-forming clouds, so it is unlikely that older pre-main sequence (PMS) stars have drifted into the field.[2] The total stellar population is 200–300.[2] The Cha I cloud is further divided into the North cloud or region and South cloud or main cloud. Star-formation began 3-4 Myrs in the southern region and 5-6 Myr ago in the northern region. The stars have a median age of about 2 Myrs.[3] The age was later revised to 1-2 Myr.[4]

HD 97300 emits X-rays, illuminates the reflection nebula IC 2631 and is one of the highest mass members of the Cha I cloud, spectral type B9V, a Herbig Ae/Be star without emission lines.[2]

Cha Helpha 1 is an object of spectral type M8 in the Chamaeleon I dark cloud that was determined in 1998 to be an X-ray source and as such is the first X-ray emitting brown dwarf found.

There are some seventy to ninety X-ray sources in the Chamaeleon I star forming region.[5] The Uhuru X-ray source (4U 1119–77) is within the Chamaeleon I cloud. This source region within the Chamaeleon I dark cloud was observed by ROSAT on February 9 at 22:14:47 UTC to February 18, 1991, 17:59:12 UTC, and on March 6, 1991, from 09:12:19 to 13:05:13 UTC.[5] This cloud contains both "weak" T Tauri (WTT) stars and "classical" T Tauri (CTT) stars.[5] Chamaeleon I X-ray ROSAT source 66 is at RA 11h 17m 36.4-37.9s Dec -77° 04' 27-50", is a CTT, Chamaeleon I No. T56, aka CTT star HM 32.[5]

The Chamaeleon I dark cloud was observed with the Imaging Proportional Counter (IPC) on board the Einstein Observatory for 2.5 h on January 23–24, 1981, identifying some 22 X-ray sources.[6] None of these sources was closer than 8' to 4U 1119–77.

A survey of stars in Chamaeleon I with VLT/SPHERE showed that 13 out of 20 systems showed a protoplanetary disk in polarized scattered light. Systems such as HD 97048, SZ Chamaeleontis, and the WW Chamaeleontis showed morphological structures. HD 97048 also shows a kink in its carbon monoxide gas disk structure, which was interpreted with the presence of a protoplanet inside around the star and inside the disk. Another notable member of Chamaeleon I is OTS 44, which is a planetary-mass object surrounded by a disk.[7] [8] [9] Another notable object is Cha J11110675-7636030, which has a mass of 3-6 and might be surrounded by a protoplanetary disk.[10]

Chamaeleon II dark cloud

Chamaeleon II contains the Uhuru source 4U 1302–77. It is close to RXJ 1303.1-7706 at RA 13h 03m 04.70s Dec -77° 06' 55.0", a K7-M0 new WTT.[1] The Chamaeleon II dark cloud contains some 40 X-ray sources.[11] Observation in Chamaeleon II was carried out from September 10 to 17, 1993.[11] Source RXJ 1301.9-7706, a new WTTS candidate of spectral type K1, is closest to 4U 1302–77.[11] Stars in Chamaeleon II have a mean age of 2-6 Myr.[12] This age was later revised to 1-2 Myr. Cha II stars have a larger disk fraction than Cha I in this study. A study with ALMA detected 22 disks around stars in Cha II in continuum.[13] There are also candidate planetary-mass objects in Cha II that are surrounded by disks.[14]

Chamaeleon III dark cloud

"Chamaeleon III appears to be devoid of current star-formation activity."[15] There are two particularly prominent nebulae associated with this area. The smaller is commonly known as the Thumbprint Nebula[16] and the larger The Talon Nebula.[17]

Extended definition

The cloud is sometimes extended with an eastern part,[18] and together with the distinctively long Dark Doodad Nebula (or Musca nebula) to the north the complex is called the Musca-Chamaeleonis Molecular Cloud.[19]

Two foreground associations are found near the Chamaeleon dark clouds. These are named after ε Chamaeleontis (3-5 Myr, distance 110 parsec)[20] and η Chamaeleontis (4-8 Myr, distance 97 parsec).[21] The proper motion of these associations are distinct from Chamaeleon I and II, but it is unclear whether the associations are physically connected to the dark clouds.[22] One notable member of the ε Chamaeleontis association is WISEA J120037.79-784508.3, which is one of the closest brown dwarfs that is surrounded by a disk.[23]

See also

Notes and References

  1. Alcala JM, Krautter J, Schmitt JH, Covino E, Wichmann R, Mundt R . A study of the Chamaeleon star forming region from the ROSAT all-sky survey. I. X-ray observations and optical identifications . Astron. Astrophys. . Nov 1995 . 114 . 11 . 109–34 . 1995A&AS..114..109A .
  2. 10.1086/423613 . Feigelson ED, Lawson WA . An X-ray census of young stars in the Chamaeleon I North Cloud . Astrophys. J. . Oct 2004 . 614 . 10 . 267–83 . 2004ApJ...614..267F. astro-ph/0406529 .
  3. Luhman . K. L. . 2007-11-01 . The Stellar Population of the Chamaeleon I Star-forming Region* . The Astrophysical Journal Supplement Series . en . 173 . 1 . 104–136 . 0710.3037 . 2007ApJS..173..104L . 10.1086/520114 . 0067-0049.
  4. Galli . P. A. B. . Bouy . H. . Olivares . J. . Miret-Roig . N. . Sarro . L. M. . Barrado . D. . Berihuete . A. . Bertin . E. . Cuillandre . J. -C. . 2021-02-01 . Chamaeleon DANCe. Revisiting the stellar populations of Chamaeleon I and Chamaeleon II with Gaia-DR2 data . Astronomy and Astrophysics . 646 . A46 . 2012.00329 . 2021A&A...646A..46G . 10.1051/0004-6361/202039395 . 0004-6361.
  5. Feigelson ED, Casanova S, Montmerle T, Guibert J . ROSAT X-Ray Study of the Chamaeleon I Dark Cloud. I. The Stellar Population . Astrophys. J. . Oct 1993 . 416 . 10 . 623–46 . 1993ApJ...416..623F . 10.1086/173264 .
  6. Feigelson ED, Kriss GA . 121939381 . Soft X-ray observations of pre-main-sequence stars in the Chamaeleon dark cloud . Astrophys. J. . Mar 1989 . 338 . 3 . 262–76 . 1989ApJ...338..262F . 10.1086/167196 . 2060/19880002197 . free .
  7. Oasa . Y. . Tamura . M. . Sugitani . K. . 1999 . A Deep Near-Infrared Survey of the Chamaeleon I Dark Cloud Core . The Astrophysical Journal . 526 . 1 . 336–343 . 1999ApJ...526..336O . 10.1086/307964 . free.
  8. Luhmann . K. L. . Peterson . D. E. . Megeath . S. T. . 2004 . Spectroscopic Confirmation of the Least Massive Known Brown Dwarf in Chamaeleon . The Astrophysical Journal . 617 . 1 . 565–568 . astro-ph/0411445 . 2004ApJ...617..565L . 10.1086/425228 . 18157277.
  9. Joergens . V. . Bonnefoy . M. . Liu . Y. . Bayo . A. . Wolf . S. . Chauvin . G. . Rojo . P. . 2013 . OTS 44: Disk and accretion at the planetary border . Astronomy & Astrophysics . 558 . L7 . 1310.1936 . 2013A&A...558L...7J . 10.1051/0004-6361/201322432 . 118456052 . 7.
  10. Esplin . T. L. . Luhman . K. L. . Faherty . J. K. . Mamajek . E. E. . Bochanski . J. J. . 2017-08-01 . A Survey for Planetary-mass Brown Dwarfs in the Chamaeleon I Star-forming Region . The Astronomical Journal . 154 . 2 . 46 . 1706.00058 . 2017AJ....154...46E . 10.3847/1538-3881/aa74e2 . free . 0004-6256.
  11. Alcalá JM, Covino E, Sterzik MF, Schmitt JH, Krautter J, Neuhäuser R . A ROSAT pointed observation of the Chamaeleon II dark cloud . Astron. Astrophys. . Mar 2000 . 355 . 3 . 629–38 . 2000A&A...355..629A .
  12. Spezzi . Loredana . Alcalá . Juan M. . Covino . Elvira . Frasca . Antonio . Gandolfi . Davide . Oliveira . Isa . Chapman . Nicholas . Evans . Neal J., II . Huard . Tracy L. . Jørgensen . Jes K. . Merín . Bruno . Stapelfeldt . Karl R. . 2008-06-01 . The Young Population of the Chamaeleon II Dark Cloud . The Astrophysical Journal . 680 . 2 . 1295–1318 . 0802.4351 . 2008ApJ...680.1295S . 10.1086/587931 . 0004-637X.
  13. Villenave . M. . Ménard . F. . Dent . W. R. F. . Benisty . M. . van der Plas . G. . Williams . J. P. . Ansdell . M. . Ribas . Á. . Caceres . C. . Canovas . H. . Cieza . L. . Hales . A. . Kamp . I. . Pinte . C. . Principe . D. A. . 2021-09-01 . Probing protoplanetary disk evolution in the Chamaeleon II region . Astronomy and Astrophysics . 653 . A46 . 2106.13847 . 2021A&A...653A..46V . 10.1051/0004-6361/202140496 . 0004-6361.
  14. Allers . K. N. . Kessler-Silacci . J. E. . Cieza . L. A. . Jaffe . D. T. . 2006-06-01 . Young, Low-Mass Brown Dwarfs with Mid-Infrared Excesses . The Astrophysical Journal . 644 . 1 . 364–377 . astro-ph/0602249 . 2006ApJ...644..364A . 10.1086/503355 . 0004-637X.
  15. Yamauchi S, Hamaguchi K, Koyama K, Murakami H . ASCA Observations of the Chamaeleon II Dark Cloud . Publ. Astron. Soc. Jpn. . Oct 1998 . 50 . 10 . 465–74 . 1998PASJ...50..465Y . 10.1093/pasj/50.5.465 . free .
  16. Lehtinen K, Mattila K, Schnur G, Prusti T. The Thumbprint nebula: The distribution of molecular gas and dust in a regular BOK globule. Astronomy and Astrophysics. 1995. 295. 487–503. 1995A&A...295..487L .
  17. Book: Chadwick . Stephen . Cooper . Ian . Imaging the Southern Sky . 11 December 2012 . Springer . 978-1461447498 . 272.
  18. Bonne . L. . Bontemps . S. . Schneider . N. . Clarke . S. D. . Arzoumanian . D. . Fukui . Y. . Tachihara . K. . Csengeri . T. . Guesten . R. . Ohama . A. . Okamoto . R. . Simon . R. . Yahia . H. . Yamamoto . H. . Formation of the Musca filament: evidence for asymmetries in the accretion flow due to a cloud–cloud collision . Astronomy & Astrophysics . EDP Sciences . 644 . 2020-11-26 . 0004-6361 . 10.1051/0004-6361/202038281 . A27. free . 2010.12479 . 2020A&A...644A..27B .
  19. Hacar . A. . Kainulainen . J. . Tafalla . M. . Beuther . H. . Alves . J. . The Musca cloud: A 6 pc-long velocity-coherent, sonic filament . Astronomy & Astrophysics . EDP Sciences . 587 . 2016-02-24 . 0004-6361 . 10.1051/0004-6361/201526015 . A97. free . 1511.06370 . 2016A&A...587A..97H .
  20. Murphy . Simon J. . Lawson . Warrick A. . Bessell . Michael S. . 2013-10-01 . Re-examining the membership and origin of the ɛ Cha association . Monthly Notices of the Royal Astronomical Society . 435 . 2 . 1325–1349 . 1305.4177 . 2013MNRAS.435.1325M . 10.1093/mnras/stt1375 . free . 0035-8711.
  21. Mamajek . Eric E. . Lawson . Warrick A. . Feigelson . Eric D. . 1999-05-01 . The η Chamaeleontis Cluster: A Remarkable New Nearby Young Open Cluster . The Astrophysical Journal . 516 . 2 . L77–L80 . 1999ApJ...516L..77M . 10.1086/312005 . 0004-637X.
  22. Lopez Martí . B. . Jimenez Esteban . F. . Bayo . A. . Barrado . D. . Solano . E. . Rodrigo . C. . 2013-03-01 . Proper motions of young stars in Chamaeleon. I. A Virtual Observatory study of spectroscopically confirmed members . Astronomy and Astrophysics . 551 . A46 . 1302.7167 . 2013A&A...551A..46L . 10.1051/0004-6361/201220128 . 0004-6361.
  23. Schutte . Maria C. . Lawson . Kellen D. . Wisniewski . John P. . Kuchner . Marc J. . Silverberg . Steven M. . Faherty . Jacqueline K. . Gagliuffi . Daniella C. Bardalez . Kiman . Rocio . Gagné . Jonathan . Meisner . Aaron . Schneider . Adam C. . Bans . Alissa S. . Debes . John H. . Kovacevic . Natalie . Bosch . Milton K.D. . 2020-08-04 . Discovery of a Nearby Young Brown Dwarf Disk . The Astrophysical Journal . 160 . 4 . 156 . 2007.15735v2 . 2020AJ....160..156S . 10.3847/1538-3881/abaccd . 1538-3881 . 220920317 . free . Luca . Hugo A. Durantini . Holden . Jonathan . Hyogo . Michiharu.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Chamaeleon complex".

Except where otherwise indicated, Everything.Explained.Today is © Copyright 2009-2025, A B Cryer, All Rights Reserved. Cookie policy.