A Caltech Library Service

ALMA Measurements of the HNC and HC_3N Distributions in Titan's Atmosphere

Cordiner, M. A. and Nixon, C. A. and Teanby, N. A. and Irwin, P. G. J. and Serigano, J. and Charnley, S. B. and Milam, S. N. and Mumma, M. J. and Lis, D. C. and Villanueva, G. and Paganini, L. and Kuan, Y.-J. and Remijan, A. J. (2014) ALMA Measurements of the HNC and HC_3N Distributions in Titan's Atmosphere. Astrophysical Journal Letters, 795 (2). Art. No. L30. ISSN 2041-8205. doi:10.1088/2041-8205/795/2/L30.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


We present spectrally and spatially resolved maps of HNC and HC_3N emission from Titan's atmosphere, obtained using the Atacama Large Millimeter/submillimeter Array on 2013 November 17. These maps show anisotropic spatial distributions for both molecules, with resolved emission peaks in Titan's northern and southern hemispheres. The HC_3N maps indicate enhanced concentrations of this molecule over the poles, consistent with previous studies of Titan's photochemistry and atmospheric circulation. Differences between the spectrally integrated flux distributions of HNC and HC_3N show that these species are not co-spatial. The observed spectral line shapes are consistent with HNC being concentrated predominantly in the mesosphere and above (at altitudes z ≳ 400 km), whereas HC_3N is abundant at a broader range of altitudes (z ≈ 70-600 km). From spatial variations in the HC_3N line profile, the locations of the HC_3N emission peaks are shown to be variable as a function of altitude. The peaks in the integrated emission from HNC and the line core (upper atmosphere) component of HC_3N (at z ≳ 300 km) are found to be asymmetric with respect to Titan's polar axis, indicating that the mesosphere may be more longitudinally variable than previously thought. The spatially integrated HNC and HC_3N spectra are modeled using the NEMESIS planetary atmosphere code and the resulting best-fitting disk-averaged vertical mixing ratio profiles are found to be in reasonable agreement with previous measurements for these species. Vertical column densities of the best-fitting gradient models for HNC and HC_3N are 1.9 × 10^(13) cm^(–2) and 2.3 × 10^(14) cm^(–2), respectively.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Cordiner, M. A.0000-0001-8233-2436
Lis, D. C.0000-0002-0500-4700
Remijan, A. J.0000-0001-9479-9287
Additional Information:© 2014 American Astronomical Society. Received 2014 August 26; accepted 2014 September 30; published 2014 October 22. This research was supported by NASA’s Planetary Atmospheres, Planetary Astronomy, and Astrobiology Programs, by The Leverhulme Trust and the UK Science and Technology Facilities Council. This Letter makes use of the following ALMA data: ADS/JAO.ALMA#2012.A.00033.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), in cooperationwith theRepublic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
Funding AgencyGrant Number
Leverhulme TrustUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Subject Keywords:planets and satellites: atmospheres; planets and satellites: individual (Titan); techniques: imaging spectroscopy; techniques: interferometric
Issue or Number:2
Record Number:CaltechAUTHORS:20150107-101730290
Persistent URL:
Official Citation:ALMA Measurements of the HNC and HC3N Distributions in Titan's Atmosphere M. A. Cordiner et al. 2014 ApJ 795 L30
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53264
Deposited By: Ruth Sustaita
Deposited On:07 Jan 2015 20:22
Last Modified:10 Nov 2021 19:50

Repository Staff Only: item control page