We present the results obtained from extensive near-infrared （IR） spectro- scopic and photometric observations of the Be/X-ray binary A0535＋262/HDE 245770 at different phases of its - 111 d orbital period. This obs...We present the results obtained from extensive near-infrared （IR） spectro- scopic and photometric observations of the Be/X-ray binary A0535＋262/HDE 245770 at different phases of its - 111 d orbital period. This observation campaign is part of the monitoring program of selective Be/X-ray binary systems aimed at understanding X-ray and near-IR properties at different orbital phases, especially during the perias- tron passage of the neutron star. The near-IR observations presented here were carried out using the 1.2 m telescope at the Mt. Abu IR Observatory. Though the source was relatively faint for spectroscopic observations with the 1.2 m telescope, we monitored the source closely during the 2011 February-March giant X-ray outburst to primarily investigate whether any drastic changes in the near-IR JHK spectra took place at the periastron passage. Changes of such a striking nature were expected to be detectable in our spectra. Photometric observations of the Be star show a gradual and systematic fading in the JHK light curves since the onset of the X-ray outburst, which could suggest a mild evacuation/truncation of the circumstellar disk of the Be companion. Near-IR spectroscopy of the object shows that the JHK spectra are dominated by the emission lines of hydrogen Brackett and Paschen series and HeI lines at 1.0830, 1.7002 and 2.0585 μm. The presence of all the hydrogen emission lines in the JHK spectra, along with the absence of any significant change in the continuum of the Be companion during X-ray quiescent and X-ray outburst phases, suggests that the near- IR line emitting regions of the disk are not significantly affected during the X-ray outburst.展开更多
We present a study of the star 2MASS J22472238＋5801214 with the aim of identifying its true nature which has hitherto been uncertain. This object, which is a member of the young cluster NGC 7380, has been variously p...We present a study of the star 2MASS J22472238＋5801214 with the aim of identifying its true nature which has hitherto been uncertain. This object, which is a member of the young cluster NGC 7380, has been variously proposed to be a Be star, a D-type symbiotic and a Herbig Ae/Be star in separate studies. Here we present optical spectroscopy, near-IR photometry and narrow band Hα imaging of the nebulosity in its environment. Analysis of all these results, including the spectral energy distribution constructed from available data, strongly indicate the source to be a Herbig Ae/Be star. The star is found to be accompanied by a nebulosity with an interesting structure. A bow-shock shaped structure, similar to a cometary nebula, is seen very close to the star with its apex oriented towards the photoionizing source of this region （i.e. the star DH Cep）. An interesting spectroscopic finding, from the forbidden [StI] 6716, 6731A and [OI] 6300A lines, is the detection of a blue-shifted high velocity outflow （200 -t-50 km s-1） from the star.展开更多
We present near-infrared spectroscopic and photometric observations of nova V5584 Sgr taken during the first 12 d following its discovery on Oct. 26.439 UT2009. The evolution of the spectra is shown from the initial P...We present near-infrared spectroscopic and photometric observations of nova V5584 Sgr taken during the first 12 d following its discovery on Oct. 26.439 UT2009. The evolution of the spectra is shown from the initial P Cygni phase to an emission line phase. The prominent carbon lines seen in the JHK spectra closely match those observed in an Fe II class nova outburst. The spectra show first-overtone CO bands in emission between 2.29-2.40 μm. By examining WISE and other publicly available data, we show that the nova underwent a pronounced dust formation phase between February- April 2010.展开更多
基金funded by the Department of Space, Government of India
文摘We present the results obtained from extensive near-infrared （IR） spectro- scopic and photometric observations of the Be/X-ray binary A0535＋262/HDE 245770 at different phases of its - 111 d orbital period. This observation campaign is part of the monitoring program of selective Be/X-ray binary systems aimed at understanding X-ray and near-IR properties at different orbital phases, especially during the perias- tron passage of the neutron star. The near-IR observations presented here were carried out using the 1.2 m telescope at the Mt. Abu IR Observatory. Though the source was relatively faint for spectroscopic observations with the 1.2 m telescope, we monitored the source closely during the 2011 February-March giant X-ray outburst to primarily investigate whether any drastic changes in the near-IR JHK spectra took place at the periastron passage. Changes of such a striking nature were expected to be detectable in our spectra. Photometric observations of the Be star show a gradual and systematic fading in the JHK light curves since the onset of the X-ray outburst, which could suggest a mild evacuation/truncation of the circumstellar disk of the Be companion. Near-IR spectroscopy of the object shows that the JHK spectra are dominated by the emission lines of hydrogen Brackett and Paschen series and HeI lines at 1.0830, 1.7002 and 2.0585 μm. The presence of all the hydrogen emission lines in the JHK spectra, along with the absence of any significant change in the continuum of the Be companion during X-ray quiescent and X-ray outburst phases, suggests that the near- IR line emitting regions of the disk are not significantly affected during the X-ray outburst.
基金funded by the Department of Space, Government of India
文摘We present a study of the star 2MASS J22472238＋5801214 with the aim of identifying its true nature which has hitherto been uncertain. This object, which is a member of the young cluster NGC 7380, has been variously proposed to be a Be star, a D-type symbiotic and a Herbig Ae/Be star in separate studies. Here we present optical spectroscopy, near-IR photometry and narrow band Hα imaging of the nebulosity in its environment. Analysis of all these results, including the spectral energy distribution constructed from available data, strongly indicate the source to be a Herbig Ae/Be star. The star is found to be accompanied by a nebulosity with an interesting structure. A bow-shock shaped structure, similar to a cometary nebula, is seen very close to the star with its apex oriented towards the photoionizing source of this region （i.e. the star DH Cep）. An interesting spectroscopic finding, from the forbidden [StI] 6716, 6731A and [OI] 6300A lines, is the detection of a blue-shifted high velocity outflow （200 -t-50 km s-1） from the star.
基金funded by the Department of Space, Government of India
文摘We present near-infrared spectroscopic and photometric observations of nova V5584 Sgr taken during the first 12 d following its discovery on Oct. 26.439 UT2009. The evolution of the spectra is shown from the initial P Cygni phase to an emission line phase. The prominent carbon lines seen in the JHK spectra closely match those observed in an Fe II class nova outburst. The spectra show first-overtone CO bands in emission between 2.29-2.40 μm. By examining WISE and other publicly available data, we show that the nova underwent a pronounced dust formation phase between February- April 2010.
