IFU Spectroscopy of the proplyd LV2

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IFU Spectroscopy of the proplyd LV2

• M. J. Vasconcelos1,2, A. H. Cerqueira1,2, H.
  Plana1, A. C. Raga2 C. Morisset3 -
  Astronomical Journal 2005 130, 170

1LATO-UESC, 2ICN-UNAM, 3IAUNAM
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Introduction

• LV2 or 167-317 is one of the most studied
  proplyds (PROto PLanetarY DiskS) in Orion
  
• Named LV2 after Laques Vidal (1979) which
  discovered 6 objects in emission close to ?1 Ori
  C and 167-317 following the notation from ODell
  Wen (1994), based on its coordinates.
• Several authors studied this object (Churchwell
  et al. 1987 Meaburn 1988 Henney et al. 2002a,
  b de la Fuente 2003a, b)
  
• 7.8 from ?1 Ori C (P. A. 34 - projected d 5
  x 1016 cm)

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• But what are proplyds?
• Low mass YSOs irradiated by external intense UV
  radiation become visible, have photoevaporated
  flows, irradiated jets,bow shaped head cometary
  shape
• First 6 objects studied by Laques Vidal (1979)
  as unresolved emission line objects
  
• ODell Wen (1994), ODell Wong (1996) ?
  dozens of proplyds with HST
  
• 160 near the Trapezium cluster (Bally et al.
  2000), more being discovered in other HII regions
  (Smith et al. 2003)

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Tail
Cusp emiting in H?, O I, N II, etc.)
Bow shock (not shown here) emiting in H?, O III
and in the IR
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Models

• Models for the
• Ionization Front (H?, O I, N II, etc.
  emission) Photodissociation and photoionization
  models by Johnstone et al. 1998, Störzer
  Hollenbach 1999, Henney Arthur 1998)
• Bow-shock (H? and O III emission)
  Garcia-Arredondo et al. (2001)
  
• Tail diffuse radiation, model by Richling
  Yorke (2000) - however, treatment of a diffusion
  equation be better

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FUV radiation dominated models
In Orion, for objects situated 1017 1018 FUV photons arrive at the disk surface and
photodissociate the material. The pressure at the
PDR (at T1000K) prevents EUV to directly reach
the disk surface.
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EUV dominated model
In Orion, for objects situated at d at d 1018 cm. At these distances, or the EUV
flux ( h? ? 13.6 eV) is too strong or the FUV
flux is too weak ? EUV photons arrive at the disk
surface, ionizing part of it.
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Bow shock
After the ionization front, high ionization arc
formed by the interaction of the supersonic
photoevaporated ionized wind with the stellar
wind.
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Observations

• System verification run of the GMOS-IFU at Gemini
  South Observatory - SV212
  
• February 2004, 300s
• FOV 3.5 x 5 with an array of 1000 lenses of
  0.2
  
• Spectral coverage 5500 Å to 7600 Å
• Instrumental profile 47 km s-1 ? FWHM ? 63 km s-1
  
  
• Data reduction with Gemini IRAF v1.6 standard
  except cosmic ray extraction which was made using
  an IDL routine and general manipulation of the
  cubes using Starlink, Fortran and IDL programs
• ? Data cubes 16 x 25 x 6257 px3 (real) and 66 x
  98 x 6257 px3 (resample)

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H? cube 66 x 98 x 6257
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Background subtraction Background nebular emiss
ion is inhomogeneous on an arc-second scale ? its
subtraction is difficult but spatially
distributed spectra help a lot.
?2 fit of an I x (x,y) plane which is subtracte
d from the remaining pixels
H?
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RESULTS
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Detected Emission Lines

• The lines detected were already reported at
  studies of the Orion Nebula (Baldwin et al.
  2000)
  
• 38 lines has been found
• Intensities of lines determined by the fitting of
  a flat continuum and the integration over the
  whole emission feature
  
• Mean flux obtained dividing the integrated flux
  by the total number of pixels of each region R1
  (187), R2 (6), R3 (1) e R4 (76)

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(No Transcript)
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Mono Maps line profiles
N II ?5755
N II ?6548
H?
N II ?6583
He I ?7065
Ar III ?7135
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Mean line profiles for each regionRegion R2
(peak emission for the proplyd) dominates the
emission in most of lines
R2
N II ?5755
N II ?6548
R3
R1
H?
N II ?6583
He I ?7065
Ar III ?7135
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Skewness (?v3)1/3 measure of velocity asymetries
H?
Ar III 7135
Increase of positive skewness to the SE
direction indicative of the presence of a
redshifted line component
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Gaussian fits to line profiles
Solid line data Crosses 3 gaussian fit For
a given pixel (6,7) ? main, blueshifted and re
dshifted components (MC, BC and RC)
vMC 40-60 km s-1 vRC 100 - 150 km s-1 vBC
- (60 - 90) km s-1
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H? Map
Pixel (6,7)
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Small decrease of the jet velocity
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Jet velocity

• Comparing the jet peak position from Bally et al.
  (2000) (0.4 from the proplyd) to its present
  position (0.67) ? proper motion of 140 km s-1
  
• From the Gaussian fit, the jet radial velocity at
  this position is (116 10) km s-1
  
• ? Similar to velocities of HH jets from T Tauri
  stars
  
• (Bally Reipurth 2002)

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Mass loss rates

• For the redshifted jet
• rB 6.7 x 1014 cm
• vj 180 km s-1, Lj 4.5 x 1015 cm
• ? Similar to mass loss rates of HH jets from T
  Tauri stars
  
• (Bally Reipurth 2002)

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Mass loss rates

• For the proplyd
• ?H? cH? / K (ODell et al. 1992)
• ?H? 5.83 x 10-14 cm3 (Effective recombination
  coef.)
  
• r0 7.9 x 1014 cm (IF radius - Henney et al.
  2002)
  
• ? Confirms previous calculations (Henney et al.
  2002)

n0 (2.3 0.6) x 106 cm-3
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Electron Density
(Osterbrock 1989)
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Below 105 cm-3 - the line ratio is a good
temperature indicator Above 105 cm-3 - the line
ratio is a good density indicator
A
Density indicator
9 UC 10 MC 11 BC
Temperature indicator
80 RC 90 MC 100 LC
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T 1.0 x 104 K
T 1.5 x 104 K
ne 2 x 106 cm-3
The ratio of S II, which is a better density
indicator, is not suitable here because the
densities are high ? high density limit and the
intensities are low
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Conclusions

• IFU spectroscopy is suitable for proplyds and is
  good for a better background subtraction
  
• Detection of 3 velocity components at the
  spectra
  
• Proplyd photoevaporated flow 28 - 33 km s-1
• Redshifted jet flow 80 - 120 km s-1
• Blueshifted component (-75 15) km s-1
• Parameters for the jet are compatible with HH
  jets from T Tauri stars
  
• Mass loss rate for the proplyd confirms previous
  results and corroborate the constraint that the
  age of ?1 Ori C should be at most 105 years