ASTE CO (3-2) observations of the southern barred spiral galaxy NGC 986: A large gaseous bar filled with a dense molecular medium

Kotaro Kohno, Tomoka Tosaki, Rie Miura, Kazuyuki Muraoka, Tsuyoshi Sawada, Kouichiro Nakanishi, Nario Kuno, Takeshi Sakai, Kazuo Sorai, Kazuhisa Kamegai, Kunihiko Tanaka, Takeshi Okuda, Akira Endo, Bunyo Hatsukade, Masahiro Sameshima, Hajime Ezawa, Seiichi Sakamoto, Takeshi Kamazaki, Nobuyuki Yamaguchi, Juan CortésYoichi Tamura, Masayuki Fukuhara, Daisuke Iono, Ryohei Kawabe

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We present CO (3-2) emission observations toward the 3′ × 3′ (or 20 kpc × 20 kpc at a distance of 23 Mpc) region of the southern barred spiral galaxy NGC 986 using the Atacama Submillimeter Telescope Experiment (ASTE). This effort is a part of our on-going extragalactic CO (3-2) imaging project, ADIoS (ASTE Dense gas Imaging of Spiral galaxies). Our CO (3-2) image revealed the presence of a large (the major axis is 14 kpc in total length) gaseous bar filled with a dense molecular medium along the dark lanes observed in optical images. This is the largest "dense-gas rich bar" known to date. The dense gas bar, discovered in NGC 986, could be a huge reservoir of possible "fuel" for future starbursts in the central region, and we suggest that star formation in the central region of NGC 986 could still be in a growing phase. We found a good spatial coincidence between the overall distributions of dense molecular gas traced by CO (3-2) and massive star formation depicted by Ha. The global CO (3-2) luminosity, L′CO(3-2), of NGC 986 was determined to be (5.4 ± 1.1) × 108 K km s-1 pc2. The CO(3-2)/CO(1-0) integrated intensity ratio was found to be 0.60 ± 0.13 at a spatial resolution of 44″ or 5 kpc, and the CO (3-2)/CO (2-1) ratio was 0.67 ± 0.14 at a beam size of ∼ 25″ or ∼ 2.8 kpc. These line ratios suggest moderate excitation conditions of CO lines (nH2 ∼ 103-4 cm-3) in a few kiloparsec region of central NGC 986.

Original languageEnglish
Pages (from-to)457-464
Number of pages8
JournalPublications of the Astronomical Society of Japan
Volume60
Issue number3
Publication statusPublished - 2008
Externally publishedYes

Fingerprint

barred galaxies
spiral galaxies
telescopes
star formation
gases
gas
experiment
molecular gases
massive stars
spatial resolution
luminosity
excitation

Keywords

  • Galaxies: individual (NGC 986)
  • Galaxies: ISM
  • Galaxies: starburst
  • Galaxies: structure
  • Submillimeter

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

ASTE CO (3-2) observations of the southern barred spiral galaxy NGC 986 : A large gaseous bar filled with a dense molecular medium. / Kohno, Kotaro; Tosaki, Tomoka; Miura, Rie; Muraoka, Kazuyuki; Sawada, Tsuyoshi; Nakanishi, Kouichiro; Kuno, Nario; Sakai, Takeshi; Sorai, Kazuo; Kamegai, Kazuhisa; Tanaka, Kunihiko; Okuda, Takeshi; Endo, Akira; Hatsukade, Bunyo; Sameshima, Masahiro; Ezawa, Hajime; Sakamoto, Seiichi; Kamazaki, Takeshi; Yamaguchi, Nobuyuki; Cortés, Juan; Tamura, Yoichi; Fukuhara, Masayuki; Iono, Daisuke; Kawabe, Ryohei.

In: Publications of the Astronomical Society of Japan, Vol. 60, No. 3, 2008, p. 457-464.

Research output: Contribution to journalArticle

Kohno, K, Tosaki, T, Miura, R, Muraoka, K, Sawada, T, Nakanishi, K, Kuno, N, Sakai, T, Sorai, K, Kamegai, K, Tanaka, K, Okuda, T, Endo, A, Hatsukade, B, Sameshima, M, Ezawa, H, Sakamoto, S, Kamazaki, T, Yamaguchi, N, Cortés, J, Tamura, Y, Fukuhara, M, Iono, D & Kawabe, R 2008, 'ASTE CO (3-2) observations of the southern barred spiral galaxy NGC 986: A large gaseous bar filled with a dense molecular medium', Publications of the Astronomical Society of Japan, vol. 60, no. 3, pp. 457-464.
Kohno, Kotaro ; Tosaki, Tomoka ; Miura, Rie ; Muraoka, Kazuyuki ; Sawada, Tsuyoshi ; Nakanishi, Kouichiro ; Kuno, Nario ; Sakai, Takeshi ; Sorai, Kazuo ; Kamegai, Kazuhisa ; Tanaka, Kunihiko ; Okuda, Takeshi ; Endo, Akira ; Hatsukade, Bunyo ; Sameshima, Masahiro ; Ezawa, Hajime ; Sakamoto, Seiichi ; Kamazaki, Takeshi ; Yamaguchi, Nobuyuki ; Cortés, Juan ; Tamura, Yoichi ; Fukuhara, Masayuki ; Iono, Daisuke ; Kawabe, Ryohei. / ASTE CO (3-2) observations of the southern barred spiral galaxy NGC 986 : A large gaseous bar filled with a dense molecular medium. In: Publications of the Astronomical Society of Japan. 2008 ; Vol. 60, No. 3. pp. 457-464.
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abstract = "We present CO (3-2) emission observations toward the 3′ × 3′ (or 20 kpc × 20 kpc at a distance of 23 Mpc) region of the southern barred spiral galaxy NGC 986 using the Atacama Submillimeter Telescope Experiment (ASTE). This effort is a part of our on-going extragalactic CO (3-2) imaging project, ADIoS (ASTE Dense gas Imaging of Spiral galaxies). Our CO (3-2) image revealed the presence of a large (the major axis is 14 kpc in total length) gaseous bar filled with a dense molecular medium along the dark lanes observed in optical images. This is the largest {"}dense-gas rich bar{"} known to date. The dense gas bar, discovered in NGC 986, could be a huge reservoir of possible {"}fuel{"} for future starbursts in the central region, and we suggest that star formation in the central region of NGC 986 could still be in a growing phase. We found a good spatial coincidence between the overall distributions of dense molecular gas traced by CO (3-2) and massive star formation depicted by Ha. The global CO (3-2) luminosity, L′CO(3-2), of NGC 986 was determined to be (5.4 ± 1.1) × 108 K km s-1 pc2. The CO(3-2)/CO(1-0) integrated intensity ratio was found to be 0.60 ± 0.13 at a spatial resolution of 44″ or 5 kpc, and the CO (3-2)/CO (2-1) ratio was 0.67 ± 0.14 at a beam size of ∼ 25″ or ∼ 2.8 kpc. These line ratios suggest moderate excitation conditions of CO lines (nH2 ∼ 103-4 cm-3) in a few kiloparsec region of central NGC 986.",
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T1 - ASTE CO (3-2) observations of the southern barred spiral galaxy NGC 986

T2 - A large gaseous bar filled with a dense molecular medium

AU - Kohno, Kotaro

AU - Tosaki, Tomoka

AU - Miura, Rie

AU - Muraoka, Kazuyuki

AU - Sawada, Tsuyoshi

AU - Nakanishi, Kouichiro

AU - Kuno, Nario

AU - Sakai, Takeshi

AU - Sorai, Kazuo

AU - Kamegai, Kazuhisa

AU - Tanaka, Kunihiko

AU - Okuda, Takeshi

AU - Endo, Akira

AU - Hatsukade, Bunyo

AU - Sameshima, Masahiro

AU - Ezawa, Hajime

AU - Sakamoto, Seiichi

AU - Kamazaki, Takeshi

AU - Yamaguchi, Nobuyuki

AU - Cortés, Juan

AU - Tamura, Yoichi

AU - Fukuhara, Masayuki

AU - Iono, Daisuke

AU - Kawabe, Ryohei

PY - 2008

Y1 - 2008

N2 - We present CO (3-2) emission observations toward the 3′ × 3′ (or 20 kpc × 20 kpc at a distance of 23 Mpc) region of the southern barred spiral galaxy NGC 986 using the Atacama Submillimeter Telescope Experiment (ASTE). This effort is a part of our on-going extragalactic CO (3-2) imaging project, ADIoS (ASTE Dense gas Imaging of Spiral galaxies). Our CO (3-2) image revealed the presence of a large (the major axis is 14 kpc in total length) gaseous bar filled with a dense molecular medium along the dark lanes observed in optical images. This is the largest "dense-gas rich bar" known to date. The dense gas bar, discovered in NGC 986, could be a huge reservoir of possible "fuel" for future starbursts in the central region, and we suggest that star formation in the central region of NGC 986 could still be in a growing phase. We found a good spatial coincidence between the overall distributions of dense molecular gas traced by CO (3-2) and massive star formation depicted by Ha. The global CO (3-2) luminosity, L′CO(3-2), of NGC 986 was determined to be (5.4 ± 1.1) × 108 K km s-1 pc2. The CO(3-2)/CO(1-0) integrated intensity ratio was found to be 0.60 ± 0.13 at a spatial resolution of 44″ or 5 kpc, and the CO (3-2)/CO (2-1) ratio was 0.67 ± 0.14 at a beam size of ∼ 25″ or ∼ 2.8 kpc. These line ratios suggest moderate excitation conditions of CO lines (nH2 ∼ 103-4 cm-3) in a few kiloparsec region of central NGC 986.

AB - We present CO (3-2) emission observations toward the 3′ × 3′ (or 20 kpc × 20 kpc at a distance of 23 Mpc) region of the southern barred spiral galaxy NGC 986 using the Atacama Submillimeter Telescope Experiment (ASTE). This effort is a part of our on-going extragalactic CO (3-2) imaging project, ADIoS (ASTE Dense gas Imaging of Spiral galaxies). Our CO (3-2) image revealed the presence of a large (the major axis is 14 kpc in total length) gaseous bar filled with a dense molecular medium along the dark lanes observed in optical images. This is the largest "dense-gas rich bar" known to date. The dense gas bar, discovered in NGC 986, could be a huge reservoir of possible "fuel" for future starbursts in the central region, and we suggest that star formation in the central region of NGC 986 could still be in a growing phase. We found a good spatial coincidence between the overall distributions of dense molecular gas traced by CO (3-2) and massive star formation depicted by Ha. The global CO (3-2) luminosity, L′CO(3-2), of NGC 986 was determined to be (5.4 ± 1.1) × 108 K km s-1 pc2. The CO(3-2)/CO(1-0) integrated intensity ratio was found to be 0.60 ± 0.13 at a spatial resolution of 44″ or 5 kpc, and the CO (3-2)/CO (2-1) ratio was 0.67 ± 0.14 at a beam size of ∼ 25″ or ∼ 2.8 kpc. These line ratios suggest moderate excitation conditions of CO lines (nH2 ∼ 103-4 cm-3) in a few kiloparsec region of central NGC 986.

KW - Galaxies: individual (NGC 986)

KW - Galaxies: ISM

KW - Galaxies: starburst

KW - Galaxies: structure

KW - Submillimeter

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