Assessment of detectability of neutral interstellar deuterium by IBEX observations

Abstract

The abundance of deuterium in the interstellar gas in front of the Sun gives insight into the processes of filtration of neutral interstellar species through the heliospheric interface and potentially into the chemical evolution of the Galactic gas. We investigate the possibility of detection of neutral interstellar deuterium at 1 AU from the Sun by direct sampling by the Interstellar Boundary Explorer (IBEX). We simulate the flux of neutral interstellar D at IBEX for the actual measurement conditions. We assess the number of interstellar D atom counts expected during the first three years of IBEX operation. We also simulate observations expected during an epoch of high solar activity. In addition, we calculate the expected counts of D atoms from the thin terrestrial water layer, sputtered from the IBEX-Lo conversion surface by neutral interstellar He atoms. Most D counts registered by IBEX-Lo are expected to originate from the water layer, exceeding the interstellar signal by 2 orders of magnitude. However, the sputtering should stop once the Earth leaves the portion of orbit traversed by interstellar He atoms. We identify seasons during the year when mostly the genuine interstellar D atoms are expected in the signal. During the first 3 years of IBEX operations about 2 detectable interstellar D atoms are expected. This number is comparable with the expected number of sputtered D atoms registered during the same time intervals. The most favorable conditions for the detection occur during low solar activity, in an interval including March and April each year. The detection chances could be improved by extending the instrument duty cycle, e.g., by making observations in the special deuterium mode of IBEX-Lo.

Accepted for Astronomy & Astrophysics

References in corpus (7)

• The Boundary Conditions of the Heliosphere: Photoionization Models Constrained by Interstellar and In Situ Data
• Density of neutral interstellar hydrogen at the termination shock from Ulysses pickup ion observations
• Local Interstellar Neutral Hydrogen sampled in-situ by IBEX
• Neutral interstellar hydrogen in the inner heliosphere under the influence of wavelength-dependent solar radiation pressure
• Local Interstellar Hydrogen's Disappearance at 1 Au: Four Years of IBEX in the Rising Solar Cycle
• Precision Pointing of IBEX-Lo Observations
• Detectability of neutral interstellar deuterium by a forthcoming SMEX mission IBEX

Cited by in corpus (11)

• Interstellar neutral helium in the heliosphere from IBEX observations. III. Mach number of the flow, velocity vector, and temperature from the first six years of measurements
• Warm Breeze from the starboard bow: a new population of neutral helium in the heliosphere
• Interstellar neutral helium in the heliosphere from IBEX observations. IV. Flow vector, Mach number, and abundance of the Warm Breeze
• Modulation of neutral interstellar He, Ne, O in the heliosphere. Survival probabilities and abundances at IBEX
• Interstellar neutral helium in the heliosphere from IBEX observations. II. The Warsaw Test Particle Model (WTPM)
• Evolution of the Solar Lyman-Alpha line profile during the solar cycle
• Interstellar Neutral Helium in the Heliosphere from IBEX Observations. I. Uncertainties and Backgrounds in the Data and Parameter Determination Method
• Interstellar neutral helium in the heliosphere from IBEX observations. V. Observations in IBEX-Lo ESA steps 1, 2, & 3
• Evolution of the solar Ly-$\alpha$ line profile during the solar cycle. II. How accurate is the present radiation pressure paradigm for interstellar neutral H in the heliosphere?
• Update of the Solar Lyman-Alpha Profile Line Model
• Science Opportunities from Observations of the Interstellar Neutral Gas with Adjustable Boresight Direction