The
Herbig-Haro objectsHH 1/2 are the first such objects to be recognized as Herbig-Haro objects and were discovered by
George Herbig and
Guillermo Haro.[3][4][2][5] They are located at a distance of about 1343
light-years (412
parsec) in the constellation
Orion near
NGC 1999.[3] HH 1/2 are among the brightest Herbig-Haro objects in the sky and consist of a pair of oppositely oriented
bow shocks, separated by 2.5
arcminutes (a projected separation of about 1.1 light year). The HH 1/2 pair were the first Herbig-Haro objects with detected
proper motion[6] and HH 2 was the first Herbig-Haro object to be detected in
x-rays.[7] Some of the structures in the Herbig-Haro Objects move with a speed of 400
km/s.[2]
The central region
The central region contains an opaque cloud core with an
astrophysical jet[8] and a highly embedded
multiple-star system that remains invisible below 3
Microns. These sources were first detected with the
Very Large Array and are therefore named VLA 1 and 2.[9] The source HH 1-2 VLA 1[10] drives the HH 1/2 pair and the source VLA 2 drives the Herbig-Haro objects HH 144/145.[11] There might be even a third outflow in the central region of HH 1/2, indicating a third member.[12]
The jet towards HH 1 is visible in optical images, but the counterjet towards HH 2 was detected in the
infrared with the
Spitzer Space Telescope.[13]
Gallery
An older version of the region mapped by the
WFPC2 of the
Hubble Space Telescope. The image also shows the jet in the lower right part in more detail
Multiple Herbig-Haro Objects mapped by the Hubble Space Telescope, including HH 2 at the lower right.
HH 47 is at the top part and part of
HH 34 is at the lower left.
The
reflection nebula NGC 1999 (blue cloud in the center) and the Herbig-Haro Objects HH 1/2 below
NGC 1999 as small pink clouds.
^Bohigas, J.; Torrelles, J. M.; Echevarria, J.; Canto, J.; Enriquez, R.; Firmani, C.; Gutierrez, L.; Ruiz, E.; Salas, L. (December 1985). "Optical images of the region around HH1 and HH2 taken with the MEPSICRON system". Revista Mexicana de Astronomía y Astrofísica. 11: 149–157.
Bibcode:
1985RMxAA..11..149B.
ISSN0185-1101.
^Rodríguez, Luis F.; Delgado-Arellano, Víctor G.; Gómez, Yolanda; Reipurth, Bo; Torrelles, José M.; Noriega-Crespo, Alberto; Raga, Alejandro C.; Cantó, Jorge (February 2000). "New VLA Observations of the HH 1-2 Region: Evidence for Density Enhancements Moving along the Axis of the VLA 1 Radio Jet". The Astronomical Journal. 119 (2): 882–889.
Bibcode:
2000AJ....119..882R.
doi:
10.1086/301231.
ISSN0004-6256.
S2CID59520064.