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Detection of argon in the coma of comet 67P/Churyumov-Gerasimenko.

Balsiger H, Altwegg K, Bar-Nun A, Berthelier JJ, Bieler A, Bochsler P, Briois C, Calmonte U, Combi M, De Keyser J, Eberhardt P, Fiethe B, Fuselier SA, Gasc S, Gombosi TI, Hansen KC, Hässig M, Jäckel A, Kopp E, Korth A, Le Roy L, Mall U, Marty B, Mousis O, Owen T, Rème H, Rubin M, Sémon T, Tzou CY, Waite JH, Wurz P - Sci Adv (2015)

Bottom Line: We report the detection of argon and its relation to the water abundance in the Jupiter family comet 67P/Churyumov-Gerasimenko by in situ measurement of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) mass spectrometer aboard the Rosetta spacecraft.Despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope (36)Ar and by the (36)Ar/(38)Ar ratio.Because of time variability and spatial heterogeneity of the coma, only a range of the relative abundance of argon to water can be given.

View Article: PubMed Central - PubMed

Affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.

ABSTRACT
Comets have been considered to be representative of icy planetesimals that may have contributed a significant fraction of the volatile inventory of the terrestrial planets. For example, comets must have brought some water to Earth. However, the magnitude of their contribution is still debated. We report the detection of argon and its relation to the water abundance in the Jupiter family comet 67P/Churyumov-Gerasimenko by in situ measurement of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) mass spectrometer aboard the Rosetta spacecraft. Despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope (36)Ar and by the (36)Ar/(38)Ar ratio. Because of time variability and spatial heterogeneity of the coma, only a range of the relative abundance of argon to water can be given. Nevertheless, this range confirms that comets of the type 67P/Churyumov-Gerasimenko cannot be the major source of Earth's major volatiles.

No MeSH data available.


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(A and B) Comparison of argon abundances to water (A) and to molecular nitrogen (B).(A and B) Relative abundances of 36Ar versus H2O (A) and N2 (B). 36Ar abundances were measured relative to water and molecular nitrogen during four periods in October 2014, when Rosetta was close to 67P/CG (10 km). Individual measurements cover 20 s. Measured particles per 20 s are plotted. Ratios are molecular ratios. (A) Large spread of the relative abundances due to the high temporal variability and spatial heterogeneity of the coma (7). (B) Good correlation between 36Ar and N2 due to their similar volatility.
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Figure 2: (A and B) Comparison of argon abundances to water (A) and to molecular nitrogen (B).(A and B) Relative abundances of 36Ar versus H2O (A) and N2 (B). 36Ar abundances were measured relative to water and molecular nitrogen during four periods in October 2014, when Rosetta was close to 67P/CG (10 km). Individual measurements cover 20 s. Measured particles per 20 s are plotted. Ratios are molecular ratios. (A) Large spread of the relative abundances due to the high temporal variability and spatial heterogeneity of the coma (7). (B) Good correlation between 36Ar and N2 due to their similar volatility.

Mentions: To constrain a possible contribution of cometary argon to Earth’s atmosphere, the abundance of argon relative to water is important. 36Ar and H2O were measured during the abovementioned four periods in October 2014, with individual measurements covering 20 s (Fig. 2A). The spread of data, as given in Fig. 2A and Table 1, is due to temporal variability and spatial heterogeneity of the coma (7). Our values for 36Ar/H2O, (0.1 to 2.3) × 10−5 (molecular ratio), are compatible with (8), one to two orders of magnitude below their upper limits determined by remote sensing of three long-period comets.


Detection of argon in the coma of comet 67P/Churyumov-Gerasimenko.

Balsiger H, Altwegg K, Bar-Nun A, Berthelier JJ, Bieler A, Bochsler P, Briois C, Calmonte U, Combi M, De Keyser J, Eberhardt P, Fiethe B, Fuselier SA, Gasc S, Gombosi TI, Hansen KC, Hässig M, Jäckel A, Kopp E, Korth A, Le Roy L, Mall U, Marty B, Mousis O, Owen T, Rème H, Rubin M, Sémon T, Tzou CY, Waite JH, Wurz P - Sci Adv (2015)

(A and B) Comparison of argon abundances to water (A) and to molecular nitrogen (B).(A and B) Relative abundances of 36Ar versus H2O (A) and N2 (B). 36Ar abundances were measured relative to water and molecular nitrogen during four periods in October 2014, when Rosetta was close to 67P/CG (10 km). Individual measurements cover 20 s. Measured particles per 20 s are plotted. Ratios are molecular ratios. (A) Large spread of the relative abundances due to the high temporal variability and spatial heterogeneity of the coma (7). (B) Good correlation between 36Ar and N2 due to their similar volatility.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643765&req=5

Figure 2: (A and B) Comparison of argon abundances to water (A) and to molecular nitrogen (B).(A and B) Relative abundances of 36Ar versus H2O (A) and N2 (B). 36Ar abundances were measured relative to water and molecular nitrogen during four periods in October 2014, when Rosetta was close to 67P/CG (10 km). Individual measurements cover 20 s. Measured particles per 20 s are plotted. Ratios are molecular ratios. (A) Large spread of the relative abundances due to the high temporal variability and spatial heterogeneity of the coma (7). (B) Good correlation between 36Ar and N2 due to their similar volatility.
Mentions: To constrain a possible contribution of cometary argon to Earth’s atmosphere, the abundance of argon relative to water is important. 36Ar and H2O were measured during the abovementioned four periods in October 2014, with individual measurements covering 20 s (Fig. 2A). The spread of data, as given in Fig. 2A and Table 1, is due to temporal variability and spatial heterogeneity of the coma (7). Our values for 36Ar/H2O, (0.1 to 2.3) × 10−5 (molecular ratio), are compatible with (8), one to two orders of magnitude below their upper limits determined by remote sensing of three long-period comets.

Bottom Line: We report the detection of argon and its relation to the water abundance in the Jupiter family comet 67P/Churyumov-Gerasimenko by in situ measurement of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) mass spectrometer aboard the Rosetta spacecraft.Despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope (36)Ar and by the (36)Ar/(38)Ar ratio.Because of time variability and spatial heterogeneity of the coma, only a range of the relative abundance of argon to water can be given.

View Article: PubMed Central - PubMed

Affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.

ABSTRACT
Comets have been considered to be representative of icy planetesimals that may have contributed a significant fraction of the volatile inventory of the terrestrial planets. For example, comets must have brought some water to Earth. However, the magnitude of their contribution is still debated. We report the detection of argon and its relation to the water abundance in the Jupiter family comet 67P/Churyumov-Gerasimenko by in situ measurement of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) mass spectrometer aboard the Rosetta spacecraft. Despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope (36)Ar and by the (36)Ar/(38)Ar ratio. Because of time variability and spatial heterogeneity of the coma, only a range of the relative abundance of argon to water can be given. Nevertheless, this range confirms that comets of the type 67P/Churyumov-Gerasimenko cannot be the major source of Earth's major volatiles.

No MeSH data available.


Related in: MedlinePlus