Observations of an Infrared Star in the Orion Nebula

Becklin, E. E.; Neugebauer, G.

doi:10.1086/149055

Cited by 165 publications

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“…There is excess emission at 6.4 keV, which we attribute to the fluorescent line, and we determine an EW of 450(220−660) eV for it. The position of COUP 599 is about 1 arcsec northwest of the BecklinNeugebauer object (Becklin & Neugebauer 1967), and as already noted by Garmire et al (2000) in a pre-COUP study, the X-ray source may be related to it, although an independent origin cannot be excluded.…”

Section: Coup 599supporting

confidence: 59%

Puzzling fluorescent emission from Orion

Czesla

Schmitt

2010

A&A

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Fluorescent X-ray emission offers a rare possibility for studying cool material surrounding active, young stars in the X-ray regime. In this work, we develop a new method to search for fluorescent emission and analyze its temporal behavior, which we apply to a sample of 106 young, active stars in Orion. Our analysis yields a sample of 23 X-ray sources with fluorescent emission, including 6 objects already reported on in an earlier study. The fluorescent sources show a wide variety of temporal behavior. While the fluorescent emission is associated with soft X-ray flares in some cases, it sometimes appears as a (quasi) persistent feature, or is seen during truly quiescent periods. We conclude that fluorescent X-ray emission can be observed in a much higher fraction of young, active stars than previously believed. Whether photoionization alone is the excitation mechanism of fluorescent X-ray emission or if electronic collisional excitation also contributes remains debatable. The temporal variability is often hard to reconcile with the photoionization model, which remains plausible if we allow for suitable geometries. Photoionization is preferred to electronic, collisional excitation mainly because the energetics of the latter challenge our current physical understanding.

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Section: Coup 599supporting

confidence: 59%

Puzzling fluorescent emission from Orion

Czesla

Schmitt

2010

A&A

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“…Appendix A (except Table A.1) is available in electronic form at http://www.aanda.org Table A.1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/559/A51 ular outflows (Wright et al 1996), a molecular hot core, and an IR luminosity of ∼10 5 L in the central part of the region, indicating the presence of embedded massive protostars (Nissen et al 2007). The Becklin-Neugebauer (BN) object was the first source of infrared radiation discovered in the Orion nebula (Becklin & Neugebauer 1967). The luminosity of the BN object is L 1500 L and it lies about 12 north of the Kleinmann-Low (KL) nebula.…”

Section: Introductionmentioning

confidence: 99%

Combined IRAM andHerschel/HIFI study of cyano(di)acetylene in Orion KL: tentative detection of DC₃N

Esplugues

Cernicharo

Viti

et al. 2013

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Context. We present a study of cyanoacetylene (HC 3 N) and cyanodiacetylene (HC 5 N) in Orion KL using observations from two line surveys performed with the IRAM 30-m telescope and the HIFI instrument onboard the Herschel telescope. The frequency ranges covered are 80−280 GHz and 480−1906 GHz. Aims. This study (divided by families of molecules) is part of a global analysis of the physical conditions of Orion KL and the molecular abundances in the different components of this cloud. Methods. We modeled the observed lines of HC 3 N, HC 5 N, their isotopologues (including DC 3 N), and vibrational modes using a non-local thermodynamic equilibrium (non-LTE) radiative transfer code. In addition, to investigate the chemical origin of HC 3 N and DC 3 N in Orion KL, we used a time-dependent chemical model. Results. We detect 40 lines of the ground vibrational state of HC 3 N and 68 lines of its 13 C isotopologues. We also detect 297 lines of six vibrational modes of this molecule (ν 7 , 2ν 7 , 3ν 7 , ν 6 , ν 5 , and ν 6 +ν 7 ) and 35 rotational lines of the ground vibrational state of HC 5 N. We report the first tentative detection of DC 3 N in a giant molecular cloud. We have obtained a DC 3 N/HC 3 N abundance ratio of 0.015 ± 0.009, similar to typical D/H ratios of cold dark clouds. We provide column densities for all species and derived isotopic and molecular abundances. We also made a 2 × 2 map around Orion IRc2 and present maps of the HC 3 N lines with energies from 34 to 154 K and of the HC 3 N vibrational modes ν 6 and ν 7 with energies between 354 and 872 K. In addition, a comparison of our results for HC 3 N with those in other clouds has allowed us to derive correlations between the column density, the FWHM, the mass, and the luminosity of the clouds. Conclusions. The high column densities of HC 3 N obtained in the hot core, in particular of the ground vibrational state and the vibrational mode ν 7 , make this molecule an excellent tracer of hot and dense gas. In addition, the wide frequency range covered reveals the need to consider a temperature and density gradient in the hot core to obtain better line fits. The high D/H ratio (similar to that obtained in cold clouds) that we derive suggests a deuterium enrichment. Our chemical models indicate that the possible deuterated HC 3 N in Orion KL is formed during the gas-phase. This fact provides new hints concerning the processes leading to deuteration.

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“…The Orion BN/KL (Becklin & Neugebauer 1967;Kleinmann & Low 1967) nebula is one of the most studied star formation regions in the Milky Way. At a distance of 414 pc (Menten et al 2007), the nebula is embedded in a giant molecular cloud harboring practically all phases of the interstellar medium, from hot and diluted plasma, to PDRs, protostellar cores, molecular outflows, SiO and H 2 O masering regions, high density cores, intermediate and high mass star formation, protoplanetary disks, and proplydes (see, e.g., Genzel et al 1980;Genzel & Stuzki 1989;Wright et al 1995;Cernicharo et al 1990Cernicharo et al , 1994Plambeck et al 2009).…”

Section: Introductionmentioning

confidence: 99%

A line-confusion limited millimeter survey of Orion KL

Tercero

Vincent

Cernicharo

et al. 2011

A&A

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Aims. We present a study of the silicon-bearing species detected in a line-confusion limited survey towards Orion KL performed with the IRAM 30-m telescope. The analysis of the line survey is organized by families of molecules. Our aim is to derive physical and chemical conditions for each family taking all observed lines into account from all isotopologs of each species. The large number of transitions in different vibrationally excited states covered by our data, which range from 80 to 280 GHz, let us provide reliable source-average column densities (hence, isotopolog abundances and vibrational temperatures) for the detected molecules. In addition, we provide a wide study of the physical properties of the source based on the different spectral components found in the emission lines. Methods. We modeled the lines of the detected molecules using a radiative transfer code, which permit us to choose between large velocity gradient (LVG) and local thermodynamic equilibrium (LTE) approximations depending on the physical conditions of the gas. We used appropriate collisional rates for the LVG calculations. To qualitatively investigate the origin of the SiS and SiO emissions in Orion KL we ran a grid of chemical models.Results. For the v = 1 state of SiO, we detected the J = 2−1 line and, for the first time in this source, emission in the J = 4−3 transition, both of them showing a strong masering effect. For SiO v = 0, we detected 28 SiO, 29 SiO, and 30 SiO; in addition, we have mapped the J = 5−4 SiO line. For SiS, we have detected the main species, 29 SiS, and SiS v = 1. Unlikely other species detected in Orion KL (IRc2), the emission peak of SiS appears at a velocity of 15.5 km s −1 . A study of the 5−4 SiO line around IRc2 shows this feature as an extended component that probably arises from the interaction of the outflow with the ambient cloud. We derive an SiO/SiS column density ratio of 13 in the plateau component, four times lower than the cosmic O/S ratio 48. In addition, we provide upper limits to the column density of several non-detected silicon-bearing species. The results of our chemical models show that while it is possible to reproduce SiO in the gas phase (as well as on the grains), SiS is a product of surface reactions, most likely involving direct reactions of sulfur with silicon.

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Observations of an Infrared Star in the Orion Nebula

Cited by 165 publications

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Puzzling fluorescent emission from Orion

Puzzling fluorescent emission from Orion

Combined IRAM andHerschel/HIFI study of cyano(di)acetylene in Orion KL: tentative detection of DC₃N

A line-confusion limited millimeter survey of Orion KL

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Observations of an Infrared Star in the Orion Nebula

Cited by 165 publications

References 0 publications

Puzzling fluorescent emission from Orion

Puzzling fluorescent emission from Orion

Combined IRAM andHerschel/HIFI study of cyano(di)acetylene in Orion KL: tentative detection of DC3N

A line-confusion limited millimeter survey of Orion KL

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Combined IRAM andHerschel/HIFI study of cyano(di)acetylene in Orion KL: tentative detection of DC₃N