Faculty Profiles - TOMITA Akihiko

Published Papers - TOMITA Akihiko

Division display101 - 120 of about 147／ All the affair displays >>

郷土の星の伝承者

富田晃彦

和歌山大学紀州経済史文化史研究所紀要 24 17 - 47 2004

A Study of Science Education Using Planetarium

佐々木順子, 富田晃彦

和歌山大学教育学部附属教育実践総合センター紀要 14 ( 14 ) 55 - 60 2004

カメラ付き携帯電話を利用した天文教育

竹中敦史, 富田晃彦

和歌山大学教育学部附属教育実践総合センター紀要 ( 14 ) 49 - 54 2004

The Virgo high-resolution CO survey: I. CO atlas

Y Sofue, J Koda, H Nakanishi, S Onodera, K Kohno, A Tomita, SK Okumura

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN ( OXFORD UNIV PRESS ) 55 ( 1 ) 17 - 58 2003.02 [Refereed]

We present the results of the Virgo high-resolution CO survey (ViCS) obtained with the Nobeyama Millimeter-wave Array (NMA). This survey was made during the course of a long-term project at Nobeyama from 1999 December through 2002 April. The objects were selected from Virgo cluster members, while considering the CO richness from the single-dish flux, mild inclination, and a lack of strong tidal perturbations. The central V regions similar to 4.7 kpc of 15 spiral galaxies were observed with resolutions of 2"-5" and 10-20 kms(-1), and sensitivities of 20 mJy beam(-1) for a 10 kms(-1) channel. The objects lie at the same distance of the Virgo cluster (16.1 Mpc), which is advantageous for comparisons among individual galaxies. We describe the details of observations and data reduction, and present an atlas of integrated CO intensity maps, velocity fields and position-velocity diagrams along the major axes. The molecular gas morphology in the Virgo galaxies shows a wealth of variety, not specifically depending on the Hubble types. Several galaxies show a strong concentration of gas in the central few kpc region, where the CO morphology shows either a "single-peak" or a "twin-peaks". The morphology of more extended CO components can be classified into "arm-type", "bar-type", and "amorphous-type".

DOI

Erratum: The Virgo High-Resolution CO Survey: I. CO Atlas (Publication of the Astronomical Society of Japan (2003) 55 (17-58))

Yoshiaki Sofue, Jin Koda, Hiroyuki Nakanishi, Sachiko Onodera, Kotaro Kohno, Akihiko Tomita, Sachiko K. Okumura

Publications of the Astronomical Society of Japan ( Oxford University Press ) 55 ( 6 ) 1189 - 1190 2003 [Refereed]

DOI

The Virgo high-resolution CO-line survey

Y Sofue, J Koda, H Nakanishi, S Onodera, K Kohno, A Tomita, SK Okumura

PROCEEDINGS OF THE IAU 8TH ASIAN-PACIFIC REGIONAL MEETING, VOL I ( ASTRONOMICAL SOC PACIFIC ) 289 129 - 134 2003 [Refereed]

We present the results of the Virgo high-resolution CO survey (VCOS) obtained with the Nobeyama Millimeter-wave Array at highangular and spectral-resolutions in the (CO)-C-12 (J = 1 - 0) line emission for 15 Virgo CO-rich spirals. The central CO distributions can be classified into the "central/single-peak type", which is a majority, and "twinpeaks". We derived exact rotation curves by applying a new iteration method to position-velocity diagrams, which show generally a steep central rise, indicating central massive cores.

Properties of spiral-peculiar type of Kiso ultraviolet-excess galaxies

A Tomita, H Maehara

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN ( OXFORD UNIV PRESS ) 54 ( 5 ) 661 - 682 2002.10 [Refereed]

We investigated the optical spectroscopic properties of 44 Kiso Ultraviolet-excess Galaxies (KUG), which is one of the most well-known catalogs of blue galaxies. All of our sample galaxies belong to the spiral-peculiar (Sp) type, the morphological class of spiral galaxy with a peculiar bar and/or a nucleus in KUGs. Since the Sp type is considered to be the most peculiar group among KUGs, and about 45% of the KUGs have the Sp type, a detailed study of the Sp type is crucial to understand the characteristics of the KUG. The sample galaxies have luminosities in the B-band of about 10(8) to less than 10(10) in solar unit, and a median physical size of 13 kpc. From the nuclear spectra, we determined line excitation sources in 39 galaxies. Among them, we detected four AGNs reliably: two Seyfert 1s, one Seyfert 2, and one LINER. Other sample galaxies show moderately star-forming activity. For this category of ordinary KUG group, the mode of the Ha equivalent width at the nuclear region is a bin of 40 to 60 Angstrom. Three galaxies have extreme starburst nuclei with an Ha equivalent width of more than 200 Angstrom. The internal extinction of A(V) is about 0.8 mag, which suggests that the star-forming nuclei are not heavily enshrouded by dust.

DOI

国際化時代の地域天体観望会：大阪日本語教育センターでの実践例

富田晃彦, 上之山幸代, 鷺坂奏絵（Part： Lead author )

和歌山大学教育学部紀要, 教育科学 70 83 - 88 2002.02

Star Formation History of Irregular Galaxies through Analysis of Optical Spectra

Tomita, A, Yoshikawa, K, Takeuchi, T.T, Hirashita, H

The Proceedings of the IAU 8th Asian-Pacific Regional Meeting, Volume II, ed. S. Ikeuchi, J. Hearnshaw, and T. Hanawa (The Astronomical Society of Japan, Tokyo) 301 - 302 2002

早期型銀河の中心部ガス系

富田晃彦

天文月報 95 ( 6 ) 278 - 281 2002

地上に残った超新星の痕跡 (翻訳)

富田晃彦

パリティ 18 ( 3 ) 39 - 42 2002

The UV (GALEX) and FIR (ASTRO-F) All Sky Surveys: the Measure of the Dust Extinction in the Local Universe

Buat, V, Takeuchi, T, Boselli, A, Burgarella, D, Hirashita, H, Tomita, A, Shibai, H, Milliard, B, Donas, J, Yoshikawa, K, Inoue, A, Tajiri, Y

The Proceedings of the IAU 8th Asian-Pacific Regional Meeting, Volume II, ed. S. Ikeuchi, J. Hearnshaw, and T. Hanawa (The Astronomical Society of Japan, Tokyo) 65 - 66 2002

GRB 020317: KISO optical observations

Tomita, A, Takeuchi, T.T, Furukawa, S, Nishibata, K, Yamamoto, M, Urata, Y, Nishiura, S, Nakata, Y, Miyata, T. Aoki, T, Soyano, T, Tarusawa, K, Mito, H, Yoshida, A, Kawai, N, Tamagawa, T

GRB Coordinates Network, Circular ( 1281 ) 1 2002

Spectroscopic observations of the star formation activities in the central regions of early-type spiral galaxies

T Usui, M Saito, A Tomita

ASTRONOMICAL JOURNAL ( UNIV CHICAGO PRESS ) 121 ( 5 ) 2483 - 2498 2001.05 [Refereed]

We study the characteristics of central star-forming regions of early-type spiral galaxies by optical spectroscopic observations. The sample consists of 13 galaxies which have ratios of far-infrared (FIR) to optical B-band luminosity, log (L-FIR/L-B), larger than the average of this type, -0.5. Strong line emissions are detected around the nucleus, and the line ratios of most regions are H II region-like, except for a few shocked regions. There is no low-ionization nuclear emission-line region (LINER). The [N II] and [S II] lines are somewhat enhanced, compared to the disk H II regions, but the enhancements cannot be attributed to hidden active galactic nuclei (AGNs) and the shock excitation. The median extinction derived from the H alpha /H beta intensity ratio is 1.0 mag in A(V), and the median SFR of our sample galaxies, corrected for extinction, is estimated to be 2 M. yr(-1). Both values are comparable to those of late-type spiral galaxies. We find a correlation that the radii of the central star-forming regions tend to become larger with the turn-over radii of the rotation curves.

DOI

The central gas systems of early-type galaxies traced by dust features, based on the Hubble Space Telescope WFPC2 archival images

A Tomita, K Aoki, M Watanabe, T Takata, S Ichikawa （Part： Lead author )

The Astronomical Journal ( UNIV CHICAGO PRESS ) 120 ( 1 ) 123 - 130 2000.07 [Refereed]

We investigated the central gas systems of E/SO galaxies by making use of the WFPC2 images in the Hubble Space Telescope archive. We searched for gas systems that were traced by the dust with a new method of making color excess images in F555W-F814W (V-I). Of 25 sample galaxies, we detected gas systems in 14 galaxies. The dust was newly detected in two galaxies that were thought to contain no dust based on single-band, prerefurbishment data. The full extents of the gas systems are 0.1-3.5 kpc, and the masses of the gas, log M-gas [M-.] are 4.2-7.2. The active galactic nucleus (AGN) activity is well correlated with the existence of the; gas systems. None of galaxies without the gas systems show AGN activity. On the other hand, some galaxies with gas systems show AGN activity; optical AGN activities are shown in five of 11 galaxies in which AGNs are optically studied, and radio activities are shown in six of 14 galaxies. This shows that the AGN activity is driven with the gas system.

Interstellar-cloud formation in the extended envelopes of blue compact dwarf galaxies

Mamoru Saito, Hideyuki Kamaya, Akihiko Tomita

Publications of the Astronomical Society of Japan ( Astronomical Society of Japan ) 52 ( 5 ) 821 - 827 2000 [Refereed]

Blue compact dwarf galaxies (BCDs) have an interesting feature in their central region where stars are actively forming. In this paper, we show that shock waves produced by the starbursts there are able to trigger self-gravitating interstellar clouds in extended envelopes, which are often observed in typical BCDs. The criterion adopted for the formation of interstellar clouds is very simple, that is, ρ &gt
2Γρ̄/3. Here, ρ is the gas density of the shocked layer, ρ̄ is a mean density including the dark matter, and Γ is a numerical factor between 0.5 and 1.0, depending on the mass distribution of the galaxy. Hence, we suggest that the infalling of the clouds onto the central regions causes subsequent starbursts after ∼ 0.1 Gyr of the event, and that the episodic starbursts continue during sub-Gyr.

DOI

InterStellar-Cloud Formation in the Extended Envelopes of Blue Compact Dwarf Galaxies

Saito, M, Kamaya, H, Tomita, A

Mapping the Hidden Universe: The Universe behind the Milky Way - The Universe in HI, ASP Conference Proceedings eds. Renee C. Kraan-Korteweg, Patricia A. Henning, and Heinz Andernach (The Astronomical Society of the Pacific) 218 305 2000

Central kinematics and rotation curve of the Sb galaxy NGC 4527 in CO, H alpha, and [NII] lines

Y Sofue, A Tomita, M Honma, Y Tutui

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN ( OXFORD UNIV PRESS ) 51 ( 5 ) 737 - 743 1999.10 [Refereed]

We have obtained interferometer observations of the central region of the Sb galaxy NGC 4527 in the CO (J = 1-0) line emission using the Nobeyama Millimeter Array. We also obtained optical (H alpha, [N II]) spectroscopy using the Okayama 188-cm reflector along the major axis. The kinematical structure and the distribution of H II regions show symmetry around the nucleus, while the distribution of molecular gas is asymmetric. The molecular-gas mass shares only 10% of the dynamical mass in the central 1 kpc radius region. Using position-velocity diagrams, we have derived a center-to-disk rotation curve. It rises steeply in the central region, attaining a maximum of about 250 km s(-1) at 400 pc radius, and then decreases to a minimum at 2 kpc radius, followed by a disk and outer flat part. The rotation curve may provide us with the most similar case to that of the Milky Way Galaxy.

DOI

Central rotation curves of spiral galaxies

Y Sofue, Y Tutui, M Honma, A Tomita, T Takamiya, J Koda, Y Takeda

ASTROPHYSICAL JOURNAL ( UNIV CHICAGO PRESS ) 523 ( 1 ) 136 - 146 1999.09 [Refereed]

We present high-resolution central-to-outer rotation curves for Sb, SBb, Sc, and SBc galaxies. We discuss their general characteristics, particularly their central behavior, as well as dependencies on morphological types, activity, and peculiarity. The rotation curves generally show a steep nuclear rise and high-velocity central rotation, followed by a broad maximum in the disk and then a flat rotation due to the massive halo. Since the central high velocity and steep rise are common to all massive galaxies, they cannot be due to noncircular motions. Disk rotation curves of barred galaxies show larger dispersion than those of normal galaxies, probably because of noncircular motions. Interacting galaxies often show perturbed outer rotation curves, while their central rotation shows no particular peculiarity. In addition, central activities, such as starbursts and active galactic nuclei, appear to show no particular correlation with the property of rotation curves. This would suggest that the central activities are triggered by a more local effect: than the global dynamical property.

Optical and CO radio observations of poor cluster Zwicky 1615.8+3505

A Tomita, H Maekara, TT Takeuchi, K Nakanishi, M Honma, Y Tutui, Y Sofue

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN ( OXFORD UNIV PRESS ) 51 ( 3 ) 285 - 300 1999.06 [Refereed]

The cluster Zwicky 1615.8+3505 is considered to be a dynamically young poor cluster. To investigate the morphology and star-formation activity of galaxies under the environment of a dynamically young poor cluster, we have performed V, R, and I surface photometry, optical low-resolution spectroscopy, and (CO)-C-12 (J = 1-0) line observations for member galaxies. Our data show that more than 90% of the observed galaxies show regular morphologies and no star-formation activities, indicating that the environment does not affect these galaxy properties. Among sixteen galaxies observed, only NGC 6104 shows a significant star-formation activity, and shows a distorted morphology, indicating a tidal interaction. This galaxy contains double knots, and only one knot possesses Seyfert activity, though the sizes and luminosities are similar to each other; we also discuss this feature.

DOI

　 PREV - NEXT 　

<TOMITA Akihiko>

Published Papers - TOMITA Akihiko