Deriving the Extinction to Young Stellar Objects using [Fe II] Near-infrared Emission Lines: Prescriptions from GIANO High-resolution Spectra

Observations of near infrared emission-lines are becoming available and can be a powerful tool to improve our knowledge on planetary nebulae properties. For wavelengths in the range 1 to 5 μm, the emission-lines correspond to atomic transitions of high ionized species of heavy elements. In particular, the [Si VI] 1.96μm and [Si VII] 2.48μm lines have already been detected (Ashley and Hyland, 1988).

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Near-Infrared Spectroscopy of NGC 253: Starburst and Surroundings

Symposium - International Astronomical Union ◽

10.1017/s0074180900233263 ◽

1996 ◽

Vol 171 ◽

pp. 407-407 ◽

Cited By ~ 1

Author(s):

D. Lutz ◽

F. Prada

Keyword(s):

Stellar Population ◽

Near Infrared ◽

Velocity Dispersion ◽

Mass Function ◽

Infrared Emission ◽

Initial Mass Function ◽

Emission Lines ◽

Lower Mass ◽

Dynamical Mass ◽

Near Infrared Emission

Near-infrared longslit spectra of NGC 253 obtained with IRSPEC at the ESO NTT are presented. By analysis of the 12CO 2.29μm bandhead we find that the stellar population in the central starburst region (r ∼ 150 pc) rotates more slowly than the gas, but has a velocity dispersion of 128 km/s, about twice the value found for emission lines from the gas in this region. This implies an about five times higher dynamical mass than previously derived (Rieke et al. 1980), removing the need to invoke a lower mass cutoff in the starburst initial mass function. The peak of near-infrared emission is displaced from the dynamical center.

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Two New T Tauri stars and a Candidate FU Orionis Star associated with Bok Globules

International Astronomical Union Colloquium ◽

10.1017/s0252921100044274 ◽

1997 ◽

Vol 163 ◽

pp. 839-839

Author(s):

J. L. Yun ◽

M. Moreira

Keyword(s):

Infrared Emission ◽

T Tauri Stars ◽

Emission Lines ◽

Young Stellar Objects ◽

Spectral Energy ◽

Energy Distributions ◽

Stellar Objects ◽

T Tauri ◽

Bok Globules ◽

Reflection Nebulae

AbstractWe present photometric and spectroscopic evidence of two new T Tauri stars formed in the conditions of isolated small Bok globules. The spectral energy distributions of these objects display excess infrared emission, they are associated with optical reflection nebulae, and their optical spectra reveal Balmer emission lines and the Li I λ6707 Å absorption line. Additionnally, we report the discovery of what is likely to be a new FU Orionis star seen towards Bok globule CB34. The star is about 4 magnitudes brighter than it appears on the Palomar plates and is associated with the aggregate of young stellar objects forming in Bok globule CB34.

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Near Infrared Emission of Neutral Carbon from Photon-Dominated Regions

Symposium - International Astronomical Union ◽

10.1017/s007418090009029x ◽

1992 ◽

Vol 150 ◽

pp. 333-334

Author(s):

V. Escalante ◽

A. Sternberg ◽

A. Dalgarno

Keyword(s):

Field Intensity ◽

Radiative Recombination ◽

Near Infrared ◽

Planetary Nebulae ◽

Infrared Emission ◽

Emission Lines ◽

Radiation Fields ◽

Ngc 7027 ◽

Near Infrared Emission ◽

Intense Radiation

Detailed calculations are reported of the intensities of the near infrared forbidden lines of neutral carbon atoms at λ 985.0 nm, 982.3 nm and 872.7 nm emitted from dense clouds subjected to intense radiation fields. The metastable levels that produce the lines are excited by radiative recombination of the C+ ions produced by photoionization. Impacts of electrons with C atoms in the heated edge zones of the clouds contribute an insignificant part to the excitation. The lines observed in M42 and NGC 2024 can be interpreted as arising in gas with densities in excess of 105 cm−3 and radiation fields with intensities between 103 and 106 times the average interstellar field intensity. Radiative recombination of C+ ions may also be an important source of the emission lines detected in the planetary nebulae NGC 6270 and NGC 7027.

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