Takashi Iijima
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Takashi Iijima has a total of 2 co-authors. Here are the top co-authors by number of shared publications:
- Daisaku Nogami
Hida Observatory, Kyoto University, Kamitakara, Gifu 506-1314
2 shared publications - Hasan H. Esenoğlu
İstanbul Üniveristesi
1 shared publication
Latest Publications
- Open Access
- 2 May 2006
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 451 (2) , 563-580
Spectral evolution of the slowest classical nova V723 Cassiopeiae in the decline stage
Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
- 2 May 2006
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 451 (2) , 563-580
Open AccessSpectral evolution of the slowest classical nova V723 Cassiopeiae in the decline stage
Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
- Open Access
- 25 March 2004
- Published by Oxford University Press (OUP) in Publications of the Astronomical Society of Japan
- Vol. 56 (sp1) , S163-S182
Dramatic Spectral Evolution of WZ Sagittae during the 2001 Superoutburst
We carried out optical spectroscopic observations of the most enigmatic dwarf nova, WZ Sge, on 11 nights during the 2001 superoutburst. Our observations covered the period from the initial phase several hours before the maximum to the ninth maximum of the rebrightening phase. The first spectrum shows absorption lines of H i (except for $$\mathrm{H}\alpha$$), H i, and Na i, as well as emission lines of H ii, C iii /N iii, and $$\mathrm{H}\alpha$$ in doubly-peaked shapes. The same spectrum shows the emission lines of C iv and N iv, which are the first detection in dwarf novae. The spectral features dramatically changed on various time scales. For example, the peak separations of the emission lines of H i and H ii changed from $$\sim 700 \,\mathrm{km} \,\mathrm{s}^{-1}$$ to $$\sim 1300 \,\mathrm{km} \,\mathrm{s}^{-1}$$, and one of the peaks dominated over an orbital period in the genuine-superhump era, but the dominant peak remained interchanged with the orbital phase in the early-superhump era. The lines of H i and H i were in emission at the minima of the rebrightening phase (with no high-excitation lines, nor Na i), while they became in absorption at the maxima. We report on the observational results in detail and their implications concerning the outburst mechanism, two types of superhumps, and the variation of the disk structure.- 25 March 2004
- Published by Oxford University Press (OUP) in Publications of the Astronomical Society of Japan
- Vol. 56 (sp1) , S163-S182
Open AccessDramatic Spectral Evolution of WZ Sagittae during the 2001 Superoutburst
We carried out optical spectroscopic observations of the most enigmatic dwarf nova, WZ Sge, on 11 nights during the 2001 superoutburst. Our observations covered the period from the initial phase several hours before the maximum to the ninth maximum of the rebrightening phase. The first spectrum shows absorption lines of H i (except for $$\mathrm{H}\alpha$$), H i, and Na i, as well as emission lines of H ii, C iii /N iii, and $$\mathrm{H}\alpha$$ in doubly-peaked shapes. The same spectrum shows the emission lines of C iv and N iv, which are the first detection in dwarf novae. The spectral features dramatically changed on various time scales. For example, the peak separations of the emission lines of H i and H ii changed from $$\sim 700 \,\mathrm{km} \,\mathrm{s}^{-1}$$ to $$\sim 1300 \,\mathrm{km} \,\mathrm{s}^{-1}$$, and one of the peaks dominated over an orbital period in the genuine-superhump era, but the dominant peak remained interchanged with the orbital phase in the early-superhump era. The lines of H i and H i were in emission at the minima of the rebrightening phase (with no high-excitation lines, nor Na i), while they became in absorption at the maxima. We report on the observational results in detail and their implications concerning the outburst mechanism, two types of superhumps, and the variation of the disk structure. - Open Access
- 1 January 2004
- Published by Cambridge University Press (CUP) in International Astronomical Union Colloquium
- Vol. 194, 232
Dramatic Spectral Evolution of WZ Sge during the 2001 Superoutburst
We spectroscopically observed WZ SGE in 11 nights during the 2001 superoutburst. The feature of the spectra dramatically varied from at the outburst maximum through during the rebrightening phase.WZ SGE is the prototypical star of WZ SGE-type stars, a small class of SU UMa-type dwarf novae. WZ SGE stars have unusual characteristics of quite large outburst amplitudes up to ~8 mag, extraordinary long recurrence cycles of the outbursts (≥10 years), no (or only a few) normal outbursts.
- 1 January 2004
- Published by Cambridge University Press (CUP) in International Astronomical Union Colloquium
- Vol. 194, 232
Open AccessDramatic Spectral Evolution of WZ Sge during the 2001 Superoutburst
We spectroscopically observed WZ SGE in 11 nights during the 2001 superoutburst. The feature of the spectra dramatically varied from at the outburst maximum through during the rebrightening phase.WZ SGE is the prototypical star of WZ SGE-type stars, a small class of SU UMa-type dwarf novae. WZ SGE stars have unusual characteristics of quite large outburst amplitudes up to ~8 mag, extraordinary long recurrence cycles of the outbursts (≥10 years), no (or only a few) normal outbursts.
- Open Access
- 6 June 2003
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 404 (3) , 997-1009
Spectral evolution of Nova (V1494) Aql and its high velocity jets
Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
- 6 June 2003
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 404 (3) , 997-1009
Open AccessSpectral evolution of Nova (V1494) Aql and its high velocity jets
Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
- Open Access
- 2 August 2002
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 391 (2) , 617-623
MWC 560: An SS 433 type object with a white dwarf
Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
- 2 August 2002
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 391 (2) , 617-623
Open AccessMWC 560: An SS 433 type object with a white dwarf
Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
- Open Access
- 17 May 2002
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 387 (3) , 1013-1021
The spectrum of the recurrent nova U Scorpii during the 1999 outburst
An optical spectrum covering the range λ λ4300–6900 Å of the recurrent nova U Sco in outburst was taken on February 26th 1999, only 16 hours after maximum. Broad emission lines of H I, He I, N II, N III were seen on the spectrum, while the emission line of He II λ4686 was not yet seen. The FWHM of the emission component of Hα was 8000 km s-1 and the FWZI was roughly 12000 km s-1. The emission line of Hα had blue (-3250 km s-1), central (+30 km s-1), and red (+2770 km s-1) peaks, among which the red one was the most prominent. A narrow absorption component of Hα blue-shifted by -4850 km s-1 was seen. The other prominent lines had a main emission peak red-shifted by km s-1 and a weak secondary peak blue-shifted by km s-1. Most of He I and N II lines were flanked by a narrow absorption component blue-shifted by about -4300 km s-1 which was a good clue for the detailed identification of these lines. These absorption components and some emission lines of N II faded very rapidly and nearly disappeared one day after our observation. The widths of the emission lines decreased with time. The radial velocities of three emission peaks of Hα were -1560 km s-1, +60 km s-1 and +1800 km s-1on March 14th, 17 days after maximum, when the blue one became stronger than the others. The helium abundance by the number of atom of the ejecta is estimated as N(He)/N(H) which is much lower than those found in previous works, and is not different from those of normal classical novae. Adopting the distance 6 kpc, the mass of the ejecta is estimated as .
- 17 May 2002
- Published by EDP Sciences in Astronomy & Astrophysics
- Vol. 387 (3) , 1013-1021
Open AccessThe spectrum of the recurrent nova U Scorpii during the 1999 outburst
An optical spectrum covering the range λ λ4300–6900 Å of the recurrent nova U Sco in outburst was taken on February 26th 1999, only 16 hours after maximum. Broad emission lines of H I, He I, N II, N III were seen on the spectrum, while the emission line of He II λ4686 was not yet seen. The FWHM of the emission component of Hα was 8000 km s-1 and the FWZI was roughly 12000 km s-1. The emission line of Hα had blue (-3250 km s-1), central (+30 km s-1), and red (+2770 km s-1) peaks, among which the red one was the most prominent. A narrow absorption component of Hα blue-shifted by -4850 km s-1 was seen. The other prominent lines had a main emission peak red-shifted by km s-1 and a weak secondary peak blue-shifted by km s-1. Most of He I and N II lines were flanked by a narrow absorption component blue-shifted by about -4300 km s-1 which was a good clue for the detailed identification of these lines. These absorption components and some emission lines of N II faded very rapidly and nearly disappeared one day after our observation. The widths of the emission lines decreased with time. The radial velocities of three emission peaks of Hα were -1560 km s-1, +60 km s-1 and +1800 km s-1on March 14th, 17 days after maximum, when the blue one became stronger than the others. The helium abundance by the number of atom of the ejecta is estimated as N(He)/N(H) which is much lower than those found in previous works, and is not different from those of normal classical novae. Adopting the distance 6 kpc, the mass of the ejecta is estimated as .
- 11 June 1998
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 297 (1) , 77-83
Eclipsing phenomena of the symbiotic star CH Cygni
- 11 June 1998
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 297 (1) , 77-83
Eclipsing phenomena of the symbiotic star CH Cygni
- 1 January 1998
- Published by Cambridge University Press (CUP) in Symposium - International Astronomical Union
- Vol. 188, 219
Variable High Velocity Jets in the Symbiotic Star CH Cygni
Highly blue or red shifted broad emission components of H I lines have been noticed in some recent spectra of the symbiotic star CH Cyg. Their intensities, profiles, and displacements from the narrow component have changed with time scale of days. For example, a blue-shifted (-1545 km s−1) intense emission component and a red-shifted weak (+757 km s−1) emission were seen on 1994 September 9. One day after, the blue-shift and red-shift became −2076 km s−1 and +1285 km s−1, respectively.
- 1 January 1998
- Published by Cambridge University Press (CUP) in Symposium - International Astronomical Union
- Vol. 188, 219
Variable High Velocity Jets in the Symbiotic Star CH Cygni
Highly blue or red shifted broad emission components of H I lines have been noticed in some recent spectra of the symbiotic star CH Cyg. Their intensities, profiles, and displacements from the narrow component have changed with time scale of days. For example, a blue-shifted (-1545 km s−1) intense emission component and a red-shifted weak (+757 km s−1) emission were seen on 1994 September 9. One day after, the blue-shift and red-shift became −2076 km s−1 and +1285 km s−1, respectively.
- 1 January 1998
- Published by Springer Nature
- p. 219
Variable High Velocity Jets in the Symbiotic Star CH Cygni
- 1 January 1998
- Published by Springer Nature
- p. 219
Variable High Velocity Jets in the Symbiotic Star CH Cygni