1. Stellar jets (I) History; Properties from observations

2. Highly collimated jets (ejected gas; supersonic velocities) are observed in many classes of astrophysical objects, both stellar and extragalactic (Livio, 2009): Stellar Extragalactic Young Stellar ObjectsActive Galactic Nuclei Massive X-Ray BinariesGamma-Ray Bursts Black Hole X-Ray Transients Low Mass X-Ray Binaries Symbiotic Stars Planetary Nebulae Nuclei Supersoft X-Ray Sources Recurrent Novae Pulsars

3. NGC 6543 NGC 6543 Crab Crab HH 111 HH 111 HH 111 M 87 NGC 6543Crab Morphology Pat Hartigan’s Home Page

4. JETS AND DISKS very different. dimensions, densities and velocities The emission mechanisms in the different classes of objects are very different. Also, are very different their dimensions, densities and velocities. Simply compare YSOs and AGNs. However, the basic mechanism for the acceleration and collimation of the jet is likely to be the same in most if not all of the different classes of objects. Jets most probably requires the presence of an accretion disk around the central object for the acceleration and collimation mechanism to operate. In the case of YSOs, accretion disks are always present in those objects with jets. Clear examples are HH 30, DG Tau B, Haro 6-5B and HK Tau.

5. Jet Origin jet velocity is always of the order of the escape velocity from the central object.most of the outflow originatesclose to the central object Observations indicate that the jet velocity is always of the order of the escape velocity from the central object. This immediately indicates that most of the outflow originates at the accretion disk close to the central object. HST images of HH 30 and DG Tau B indeed show that the jets are emanating from the central part of the accretion disk.

6. OPTICAL Herbig-Haro Objects; discovered in the early 50s First symposium in 1983 (Bohm, ed.) 1980s - HH objects part of bipolar outflows (Dopita; Mundt; Graham; Reipurth) Spectroscopy; proper motion studies; modeling 1990s - HST … 1994 Herbig & Jones 1981Bally et al. 2002

7. HH 212 Wiseman, J. ApJ, 550, L87 (2001 ApJ, 550, L87 (2001) NH 3 NH 3 (disk) protostar H 2 2,12  m (NIR, K-band)

8. Davis et al. 1994, 2000 NEAR-IR NEAR-IR H 2 emission lines discovered in Orion; Gautier 1976 High-resolution studies of outflows from more embedded sources! 1980s - spectroscopy; molecular shock physics (theory) 1990s - First sub-arcsec images; high-resol. spec. (CGS4) - kinematics and excitation - numerical simulations; bows; entrainment Calar Alto 1993 UKIRT 1999

9. (SUB)-MILLIMETRE Broad CO lines in Orion (Kwan & Scoville 1976) 1980s - CO surveys in the (Snell, Bally, Edwards, Lada) 1990s - Higher-energy lines (submm @ JCMT); isotopes; shock chemistry in outflows; entrainment models Interferometry @ Plateau de Bure, CARMA, SMA - molecular “jets”; study of massive Star-Forming regions. Davis & Eisloeffel 1996Gueth et al. 1998Beltran et al. 2004

10. JETS FROM YSOs Herbig-Haro Objects Herbig Haro JETS FROM YSOs Herbig-Haro Objects T he history of jets from YSOs began with the discovery of the Herbig-Haro objects by George Herbig and Guillermo Haro in the late 40’ s of the past century. These enigmatic objects showed rather peculiar characteristics: they were small nebulae (a few tens of arcsec in size), with an strange spectrum (very different from any known at that time) and, most intriguing, far away from any powering source. Herbig’s Catalog (1974)

11. Bally et al. AJ 123, 2627 (2002) HH 1-2

12. Discovered by: **G.H.Herbig(1951): The spectra of two nebulous objects near NGC 1999 (ApJ 113, 697). On a series of direct photographs taken with the Crosslyer reflector in 1946 and 1947 and centered on the diffuse nebula NGC 1999, there appear several peculiar nebulous objects. The brightest of these (referred to hereafter as "No. 1") resembles, on the best plates, a slightly diffuse star with a very short curved, nebulous "tail" extending for 5" in p.a. 52º. Its visual magnitude was estimated at the telescope to be near 16. It lies 1'.0 west and 2'.2 south of BD-6 1253, the illuminating star of NGC 1999. Object No.2, which is 0'.1 east and 4'.1 south of BD6 1253, is composed of two faint stars 9" apart, one much fainter star, and three closely associated semistellar clots of nebulosity; the entire object would be contained in a circle 20" in diameter. It is superimposed on much fainter nebulosity in the form of a ring, and slit spectrograms indicate that still feebler emission nebulosity is present over the entire field. The two brighter stars in object No.2 were estimated to be about visual magnitude 17.5.

13. and **G. Haro ApJ 115, 572 (1952) In a recently published note G.H.Herbig (ApJ 113,697, 1951) reports the discovery of three peculiar nebulous objects near NGC 1999 and gives the spectroscopic description of the two brightest. The writer had independently discovered these peculiar objects, finding Ha and the [O I] lines at  6300 and  6363 in emission in the spectra of them. First spectrophotometric study by: Karl-Heinz Böhm (ApJ 123, 379, 1956) Relative intensities of the emission lines in the spectrum of the brightest Herbig-Haro Object have been determine from three spectrograms taken by Herbig in January, 1955. radiation is produced by a "central star" (of solar dimension) in the nebula Therefore, the most obvious means of explaining the ionization is to assume a strong radiation field in the far ultraviolet. If the radiation is produced by a "central star" (of solar dimension) in the nebula, a radiation temperature of 24000° K is required to explain the observed ratio of [ O II] and [O III].

15. BUT : ** Deep optical and NIR images fail to detect the embedded star (inside the HH nebulosity) ( Haro, G., Minkowski, R.: 1960, The Herbig-Haro objects near NGC 1999, AJ 65, 490). ** Variability of the HH nebulosities: The nebulosities change their brightness, dissapear and move relative to Field stars with a scale of time of several yrs All of this goes in favour of the exciting source being located outside of the HH nebulosity.

16. HHs=reflection nebulae illuminated by an external source Strom, S. E., Grasdalen, G. L., & Strom, K. M. Infrared and optical observations of Herbig-Haro objects ApJ., 191, 111-142 (1974)

17. “old example” BURNHAM NEBULA (HH 255) Burnham Nebula was discovered by Burnham (1984) as a small nebula some arcsec to the south of T-Tau. (Burnham, S.W., Observations of Nebulae with the 36-inch refractor of the Lick Observatory, Pub. Lick Obs., 2, 1689) From high-resolution long-slit spectra in the range 6250-6800 A Emission nebulosities around T-Tau (Böhm & Solf 1994 ApJ, 430, 277).

18. ASSOCIATED WITH TTS ** **(Osterbrock, 1958): supersonic gas, ejected by a TTS, excites the surrounding nebula and produces the observed emission lines. ** ** Supersonic stellar wind interaction with the ambient gas HH is created Radiative shock HH is created CATALOGS: *Herbig *Herbig (1974) ~40 objects*Reipurth http://www.astro.umass.edu/catalogs/HHcat/HHintro.html#home (> 1000, in progress)

19. spectrum is produced in the cooling region of fast shock waves. Today we know that they are just either the brightest parts of the very collimated outflows or jets produced by young stellar objects or in the region of where the jet hits the surrounding medium. The characteristic spectrum is produced in the cooling region of fast shock waves. HH 34HH 1/ 2

20. A) Morphology Bipolar with a slight difference in direction between jet and counterjet. Extremely well collimated with small opening angles of no more than a few degrees. Many are not perfectly straight, but show a gradual change in direction or bending. Lengths around a fraction of a parsec, although, in some cases the jet can be traced for several parsecs from the source. Widths between 50-500 AU. They show a series of bright, almost equidistant, knots inside the body of the jet. Jet properties

21. Highly collimated morphology wiggling HH30 jet/counterjet system [SII] CCD image Acquired with ACAM (WHT)

22. HH 110 HH 270 “JETS” in ORION Reipurt & Bally

23. HH 110 [SII] CCD image with NOT/ALFOSC N HH 270 ~4 ARCMIN Lack of exciting source? Kno t More “chaotic” morphology

24. Hartigan et al. (2005), AJ 130, 2197 “curved” morphology +”bow-shock”

25. Straightmorphology Terminal bow-shock IWS

26. Exciting source: YSO surounded by a circunstellar diskNIR: H 2 [FeII]Optical: [SII] H  9” (4,000 AU) HH111 (Orion) (Orion) (Reipurth et al. 1999) knot Bow-shock

27. Molecular Outflows High-velocity molecular outflows is a very common phenomenon clearly related to jets in YSOs. When both phenomena are observed, both coincide in direction and sense. They are observed in lines of many molecules, most notably in H 2 and CO.

28. Observations Mostly bipolar. Wider and longer than the jet. Velocities in the range from a few km/s to less than a hundred. Sizes ranging from less than 0.1 pc to several parsecs. Kinematical time-scales from about 10 3 to 10 5 yr. Masses from a few 10 -4 to several hundreds M sun. Conclusions So massive that they must consist of accelerated ambient molecular material. The momentum and power of the ionized jet component is usually not enough for the required acceleration. An additional wide-angle wind is probably required to explain the observed morphologies and to easy the momentum problem.

29. Sub and mm wvl Optical/Nir wvl Unified model: molecular outflow/ Jet HHs

30. Formation Mechanism The most likely mechanism for the launching of the jet from the disk involves hydromagnetic acceleration and collimation. That is, the outflow is initially controlled by a strong magnetic field anchored to the disk and the central object.