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Title: Spectral Evidence for an Inner Carbon-rich Circumstellar Belt in the Young HD 36546 A-star System

Abstract

Using the NASA/IRTF SpeX and BASS spectrometers we have obtained 0.7–13 μ m observations of the newly imaged 3–10 Myr old HD 36546 disk system. The SpeX spectrum is most consistent with the photospheric emission expected from an L {sub *} ∼ 20 L {sub ⊙}, solar abundance A1.5V star with little to no extinction, and excess emission from circumstellar dust detectable beyond 4.5 μ m. Non-detections of CO emission lines and accretion signatures point to the gas-poor circumstellar environment of a very old transition disk. Combining the SpeX + BASS spectra with archival WISE / AKARI / IRAS / Herschel photometry, we find an outer cold dust belt at ∼135 K and 20–40 au from the primary, likely coincident with the disk imaged by Subaru, and a new second inner belt with a temperature ∼570 K and an unusual, broad SED maximum in the 6–9 μ m region, tracing dust at 1.1–2.2 au. An SED maximum at 6–9 μ m has been reported in just two other A-star systems, HD 131488 and HD 121191, both of ∼10 Myr age. From Spitzer , we have also identified the ∼12 Myr old A7V HD 148657 system as having similar 5–35 μmore » m excess spectral features. The Spitzer data allows us to rule out water emission and rule in carbonaceous materials—organics, carbonates, SiC—as the source of the 6–9 μ m excess. Assuming a common origin for the four young A-star systems’ disks, we suggest they are experiencing an early era of carbon-rich planetesimal processing.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8]
  1. JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States)
  2. Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011 and Space Science Institute, Boulder, CO 80301 (United States)
  3. The Aerospace Corporation, Los Angeles, CA 90009 (United States)
  4. Department of Physics and Astronomy, 12 Physics Hall, Iowa State University, Ames, IA 50010 (United States)
  5. Subaru Telescope, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Hilo, HI 96720 (United States)
  6. Center for Astrophysics and Space Sciences, University of California, San Diego, CA 92093-0424 (United States)
  7. Department of Earth and Planetary Sciences, McCone Hall, University of California at Berkeley, Berkeley, CA 94720 (United States)
  8. Department of Physics and Astronomy, University of Georgia, Athens, GA 30602-2451 (United States)
Publication Date:
OSTI Identifier:
22654479
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 840; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CARBON; CARBON MONOXIDE; CARBONACEOUS MATERIALS; DETECTION; DUSTS; EMISSION; IMAGES; NASA; PHOTOMETRY; SCATTERING; SILICON CARBIDES; SPECTRA; SPECTROMETERS; STARS; WATER

Citation Formats

Lisse, C. M., Sitko, M. L., Russell, R. W., Marengo, M., Currie, T., Melis, C., Mittal, T., and Song, I., E-mail: carey.lisse@jhuapl.edu, E-mail: ron.vervack@jhuapl.edu, E-mail: sitkoml@ucmail.uc.edu, E-mail: ray.russell@aero.org, E-mail: mmarengo@iastate.edu, E-mail: currie@naoj.org, E-mail: cmelis@ucsd.edu, E-mail: tmittal2@berkeley.edu, E-mail: song@physast.uga.edu. Spectral Evidence for an Inner Carbon-rich Circumstellar Belt in the Young HD 36546 A-star System. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA6EA3.
Lisse, C. M., Sitko, M. L., Russell, R. W., Marengo, M., Currie, T., Melis, C., Mittal, T., & Song, I., E-mail: carey.lisse@jhuapl.edu, E-mail: ron.vervack@jhuapl.edu, E-mail: sitkoml@ucmail.uc.edu, E-mail: ray.russell@aero.org, E-mail: mmarengo@iastate.edu, E-mail: currie@naoj.org, E-mail: cmelis@ucsd.edu, E-mail: tmittal2@berkeley.edu, E-mail: song@physast.uga.edu. Spectral Evidence for an Inner Carbon-rich Circumstellar Belt in the Young HD 36546 A-star System. United States. doi:10.3847/2041-8213/AA6EA3.
Lisse, C. M., Sitko, M. L., Russell, R. W., Marengo, M., Currie, T., Melis, C., Mittal, T., and Song, I., E-mail: carey.lisse@jhuapl.edu, E-mail: ron.vervack@jhuapl.edu, E-mail: sitkoml@ucmail.uc.edu, E-mail: ray.russell@aero.org, E-mail: mmarengo@iastate.edu, E-mail: currie@naoj.org, E-mail: cmelis@ucsd.edu, E-mail: tmittal2@berkeley.edu, E-mail: song@physast.uga.edu. Wed . "Spectral Evidence for an Inner Carbon-rich Circumstellar Belt in the Young HD 36546 A-star System". United States. doi:10.3847/2041-8213/AA6EA3.
@article{osti_22654479,
title = {Spectral Evidence for an Inner Carbon-rich Circumstellar Belt in the Young HD 36546 A-star System},
author = {Lisse, C. M. and Sitko, M. L. and Russell, R. W. and Marengo, M. and Currie, T. and Melis, C. and Mittal, T. and Song, I., E-mail: carey.lisse@jhuapl.edu, E-mail: ron.vervack@jhuapl.edu, E-mail: sitkoml@ucmail.uc.edu, E-mail: ray.russell@aero.org, E-mail: mmarengo@iastate.edu, E-mail: currie@naoj.org, E-mail: cmelis@ucsd.edu, E-mail: tmittal2@berkeley.edu, E-mail: song@physast.uga.edu},
abstractNote = {Using the NASA/IRTF SpeX and BASS spectrometers we have obtained 0.7–13 μ m observations of the newly imaged 3–10 Myr old HD 36546 disk system. The SpeX spectrum is most consistent with the photospheric emission expected from an L {sub *} ∼ 20 L {sub ⊙}, solar abundance A1.5V star with little to no extinction, and excess emission from circumstellar dust detectable beyond 4.5 μ m. Non-detections of CO emission lines and accretion signatures point to the gas-poor circumstellar environment of a very old transition disk. Combining the SpeX + BASS spectra with archival WISE / AKARI / IRAS / Herschel photometry, we find an outer cold dust belt at ∼135 K and 20–40 au from the primary, likely coincident with the disk imaged by Subaru, and a new second inner belt with a temperature ∼570 K and an unusual, broad SED maximum in the 6–9 μ m region, tracing dust at 1.1–2.2 au. An SED maximum at 6–9 μ m has been reported in just two other A-star systems, HD 131488 and HD 121191, both of ∼10 Myr age. From Spitzer , we have also identified the ∼12 Myr old A7V HD 148657 system as having similar 5–35 μ m excess spectral features. The Spitzer data allows us to rule out water emission and rule in carbonaceous materials—organics, carbonates, SiC—as the source of the 6–9 μ m excess. Assuming a common origin for the four young A-star systems’ disks, we suggest they are experiencing an early era of carbon-rich planetesimal processing.},
doi = {10.3847/2041-8213/AA6EA3},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 840,
place = {United States},
year = {Wed May 10 00:00:00 EDT 2017},
month = {Wed May 10 00:00:00 EDT 2017}
}