Evidence of direct detection of interstellar deuterium in the local interstellar medium by IBEX

Rodriguez Moreno, Diego Francisco; Wurz, Peter; Saul, Lukas; Bzowski, M.; Kubiak, M. A.; Sokół, J. M.; Frisch, P.; Fuselier, S. A.; McComas, D. J.; Möbius, E.; Schwadron, N. (2013). Evidence of direct detection of interstellar deuterium in the local interstellar medium by IBEX. Astronomy and astrophysics, 557(A125), A125. EDP Sciences 10.1051/0004-6361/201321420

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We report the first in situ measurements of neutral deuterium originating in the local interstellar medium (LISM) in Earth’s orbit. These measurements were performed with the IBEX-Lo camera on NASA’s interstellar boundary explorer (IBEX) satellite. All data from the spring observation periods of 2009 through 2011 have been analysed. In the three years of the IBEX mission time, the observation geometry and orbit allowed for a total observation time of 115.3 days for the LISM. However, the effects of the spinning spacecraft and the stepping through 8 energy channels mean that we are only observing the interstellar wind for a total time of 1.44 days, in which 2 counts for interstellar deuterium were collected. We report here a conservative number, because a possibility of systematic error or additional noise, though eliminated in our analysis to the best of our knowledge, only supports detection at a 1-sigma level. From these observations, we derive a ratio D/H = (5.8 ± 4.4) × 10-4 at 1 AU. After modelling the transport and loss of D and H from the termination shock to Earth’s orbit, we find that our result of D/HLISM = (1.6 ± 1.2) × 10-5 agrees with D/HLIC = (1.6 ± 0.4) × 10-5 for the local interstellar cloud. This weak interstellar signal is extracted from a strong terrestrial background signal consisting of sputter products from the sensor’s conversion surface. As reference, we accurately measure the terrestrial D/H ratio in these sputtered products and then discriminate this terrestrial background source. Because of the diminishing D and H signal at Earth’s orbit during the rising solar activity due to photoionisation losses and increased photon pressure, our result demonstrates that in situ measurements of interstellar deuterium in the inner heliosphere are only possible during solar minimum conditions.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences

UniBE Contributor:

Rodriguez Moreno, Diego Francisco; Wurz, Peter and Saul, Lukas

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science > 530 Physics

ISSN:

0004-6361

Publisher:

EDP Sciences

Language:

English

Submitter:

Cléa Serpollier

Date Deposited:

10 Jul 2014 16:46

Last Modified:

28 Jun 2016 16:44

Publisher DOI:

10.1051/0004-6361/201321420

BORIS DOI:

10.7892/boris.44303

URI:

https://boris.unibe.ch/id/eprint/44303

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