BHR 71

BHR 71
Dark nebula
BHR 71 with James Webb Space Telescope NIRCam
Observation data: epoch
Right ascension12h 01m 37.0s
Declination−65° 08′ 48″
Distance600 ly
ConstellationMusca
Physical characteristics
Radius1 ly
DesignationsBHR 71, Sandqvist 136
See also: Lists of nebulae

BHR 71 (also known as Sandqvist 136) is a small dark nebula and a bok globule in the constellation of Musca which is 600 light years from the Solar System. It has a diameter of about 1 light year. The globule has a mass of 40 M☉ and a kinetic temperature of 11 Kelvin.

Discovery

BHR 71 is also called Sandqvist 136 and was discovered in 1977 by A. Sandqvist with the ESO B Atlas. In 1995 it was included in a catalogue by T. L. Bourke, A. R. Hyland and G. Robinson, which lists small molecular clouds, called globule. The listed objects were later given the acronym BHR, using the first letters of the surnames of the authors.

Binary Protostar

In 1997 a study discovered a highly collimated bipolar outflow in the center of the bok globule. This originates from a class 0 protostar called IRAS 11590-6452.

In 2001 new observations in the near-infrared with the Anglo-Australian Telescope and carbon monoxide (CO) observations with the Swedish-ESO Submillimetre Telescope found that the source was in fact two individual protostars called IRS 1 and IRS 2. The protostars have a separation of about 17 arcseconds (or 3400 AU). Each protostar is driving its own molecular outflow, with IRS 1 driving the larger outflow and being more massive. The objects were observed with the Australian Telescope Compact Array and the Spitzer Space Telescope. This study found that the binary is the result of a rotational fragmentation of a single collapsing protostellar core. A later study using ALMA did, however, find that the binary formed via turbulent fragmentation of the core.

Dust observations with ALMA did find compact objects with no clear keplerian motion, meaning potential disks are not detected. The disks are likely deeply embedded in an envelope and therefore not detected. The researchers were able to set upper limits of the mass of the protostars. IRS 1 has an upper limit of 0.46 M☉ and IRS 2 has an upper limit of 0.26 M☉.

The outflows

Left: Very Large Telescope image of BHR 71; middle: Spitzer image of BHR 71; right: combined image

In 1997 the Herbig-Haro objects 320 and 321 were discovered in BHR 71 with the help of sulfur [S II] imaging. The position of HH 320/321 in the 1997 paper are incorrect and were later corrected. A study using ALMA revealed that two of the outflows are partially colliding with each other. CO images show increased brightness at the collision area, the dispersion of velocity and the change in orientation for one outflow. This study also showed that IRS 2 is closer to us when compared to IRS1. The jet of IRS 1 shows a double-helical structure, which is evidence of removal of angular momentum in the system. IRS 2 on the other hand has a very collimated jet, showing knots, which is evidence for episodic accretion.

References

  1. ↑ California Institute of Technology. "Spitzer Infrared Image of BHR 71". Jet Propulsion Laboratory. NASA. Retrieved 10 July 2010.
  2. 1 2 Bourke, Tyler L.; Garay, Guido; Lehtinen, Kimmo K.; Köhnenkamp, Ive; Launhardt, Ralf; Nyman, Lars-Å; May, Jorge; Robinson, Garry; Hyland, A. R. (February 1997). "Discovery of a Highly Collimated Molecular Outflow in the Southern Bok Globule BHR 71". The Astrophysical Journal. 476 (2): 781–800. Bibcode:1997ApJ...476..781B. doi:10.1086/303642. ISSN 0004-637X.
  3. ↑ Sandqvist, Aa (May 1977). "More southern dark dust clouds". Astronomy and Astrophysics. 57: 467–470. Bibcode:1977A&A....57..467S. ISSN 0004-6361.
  4. ↑ Bourke, T. L.; Hyland, A. R.; Robinson, G. (October 1995). "Studies of star formation in isolated small dark clouds - I. A catalogue of southern BOK globules: optical and IRAS properties". Monthly Notices of the Royal Astronomical Society. 276 (4): 1052–1066. Bibcode:1995MNRAS.276.1052B. doi:10.1093/mnras/276.4.1052. ISSN 0035-8711.
  5. 1 2 Bourke, Tyler L. (June 2001). "IRAS 11590-6452 in BHR 71: A Binary Protostellar System?". The Astrophysical Journal. 554 (1): L91–L94. arXiv:astro-ph/0105204. Bibcode:2001ApJ...554L..91B. doi:10.1086/320921. ISSN 0004-637X.
  6. ↑ Chen, Xuepeng; Launhardt, Ralf; Bourke, Tyler L.; Henning, Thomas; Barnes, Peter J. (August 2008). "ATCA and Spitzer Observations of the Binary Protostellar Systems CG 30 and BHR 71". The Astrophysical Journal. 683 (2): 862–875. arXiv:0805.1533. Bibcode:2008ApJ...683..862C. doi:10.1086/589939. ISSN 0004-637X.
  7. ↑ Tobin, John J.; Bourke, Tyler L.; Mader, Stacy; Kristensen, Lars; Arce, Hector; Gueth, Frédéric; Gusdorf, Antoine; Codella, Claudio; Leurini, Silvia; Chen, Xuepeng (January 2019). "The Formation Conditions of the Wide Binary Class 0 Protostars within BHR 71". The Astrophysical Journal. 870 (2): 81. arXiv:1811.03059. Bibcode:2019ApJ...870...81T. doi:10.3847/1538-4357/aaef87. ISSN 0004-637X.
  8. 1 2 Gavino, Sacha; Jørgensen, Jes K.; Sharma, Rajeeb; Yang, Yao-Lun; Li, Zhi-Yun; Tobin, John J.; Ohashi, Nagayoshi; Takakuwa, Shigehisa; Plunkett, Adele L.; Kwon, Woojin; de Gregorio-Monsalvo, Itziar; Lin, Zhe-Yu Daniel; Santamaría-Miranda, Alejandro; Aso, Yusuke; Sai, Jinshi (October 2024). "Early Planet Formation in Embedded Disks. XI. A High-resolution View Toward the BHR 71 Class 0 Protostellar Wide Binary". The Astrophysical Journal. 974 (1): 21. arXiv:2407.17249. Bibcode:2024ApJ...974...21G. doi:10.3847/1538-4357/ad655e. ISSN 0004-637X.
  9. ↑ Corporon, Patrice; Reipurth, Bo (1997). "Herbig--Haro objects in SA 136". Herbig-Haro Flows and the Birth of Stars. 182: 85. Bibcode:1997IAUS..182P..85C. ISSN 1743-9221.
  10. ↑ Zapata, Luis A.; Fernández-López, Manuel; Rodríguez, Luis F.; Garay, Guido; Takahashi, Satoko; Lee, Chin-Fei; Hernández-Gómez, Antonio (November 2018). "ALMA Reveals a Collision between Protostellar Outflows in BHR 71". The Astronomical Journal. 156 (5): 239. arXiv:1804.00625. Bibcode:2018AJ....156..239Z. doi:10.3847/1538-3881/aae51e. ISSN 0004-6256.