Phase-dependent Photometric and Spectroscopic Characterization of the MASTER-Net Optical Transient J212444.87+321738.3: An Oxygen-rich Mira

Ghosh, S. K.; Mondal, Soumen; Das, Ramkrishna; Banerjee, D. P. K.; Ashok, N. M.; Hambsch, Franz-Josef; Dutta, Somnath

doi:10.3847/1538-3881/aab902

Cited by 7 publications

(8 citation statements)

References 88 publications

(104 reference statements)

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“…The YJ mode covers Y and J windows (1.02-1.49 µm) and the HK mode covers H and K windows (1.50-1.84 µm and 1.95-2.45 µm). For imaging observations, the instrument provides broad band J, et al, 2020), K-M giants (Ghosh et al, 2019), asymptotic giant branch stars (e.g., Ghosh et al 2018Ghosh et al , 2021Susmitha et al 2021) and supernova (Srivastav et al, 2016). Currently, about 50% of the observing proposals on HCT use TIRSPEC as a focal plane instrument.…”

Section: Tifr Near Infrared Spectrometer and Imager (Tirspec)mentioning

confidence: 99%

TIFR Treasures for Astronomy from Ground to Space

Ghosh,

Ojha,

Sharma

et al. 2021

Preprint

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The infrared astronomy group of Department of Astronomy and Astrophysics at Tata Institute of Fundamental Research has been pursuing astronomical instrumentation activities since its inception. The group has been routinely involved in balloon-borne astronomy program from field station at Hyderabad with indigenously developed payloads. Ground-based astronomical activities began with a single element infrared detector. Later, over time, larger format array detectors are being used in the cameras. These astronomy cameras have been routinely used at observatories across India. Recently, the group has also developed a laboratory model of the Infrared Spectroscopic Imaging Survey payload, targeted for the small satellite mission of the Indian Space Research Organisation, which will carry out spectroscopic measurements in the wavelength range 1.7 to 6.4 µm seamlessly.

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Section: Tifr Near Infrared Spectrometer and Imager (Tirspec)mentioning

confidence: 99%

TIFR Treasures for Astronomy from Ground to Space

Ghosh,

Ojha,

Sharma

et al. 2021

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“…Both methods of reduction match well. The additional details of the reduction process can be found in Ghosh et al (2018).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…The optical light curves in the R-and I-band are shown in Figure 2 and time-series RI magnitudes are listed in Table 2. To estimate the period of the object, we applied the Fourier decomposition technique (Ngeow et al 2013;Ghosh et al 2018),…”

Section: Optical Light Curves and Periodmentioning

confidence: 99%

“…Previous studies unveil not only the considerable and independent variation of individual spectral features (optical TiO and VO bands: Alvarez & Plez 1998 and NIR CO, OH and H 2 O lines: Hinkle et al 1982or Lebzelter et al 1999) over the phase but also their cycle-to-cycle variation. The line profiles of molecular lines are also affected because of the velocity field variation, while the molecular abundances in the atmosphere are influenced by the luminosity variation (Liljegren et al 2017;Ghosh et al 2018). Moreover, the NIR spectrum of OH/IR stars is strongly influenced by the dust, OH radical and water content in the outer atmosphere (Bessell et al 1996; Vanholle- ).…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic and photometric monitoring of a poorly known high-luminous OH/IR star: IRAS 18278+0931

Ghosh,

Mondal,

Das

et al. 2021

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We present the time-dependent properties of a poorly known OH/IR star − IRAS 18278+0931 (hereafter, IRAS 18+09) towards the Ophiuchus constellation. We have carried out long-term optical/nearinfrared (NIR) photometric and spectroscopic observations to study the object. From optical R-and I-band light curves, the period of IRAS 18+09 is estimated to be 575 ± 30 days and the variability amplitudes ranges from ∆R ∼ 4.0 mag to ∆I ∼ 3.5 mag. From the standard Period-Luminosity (PL) relations, the distance (D) to the object, 4.0±1.3 kpc, is estimated. Applying this distance in the radiative transfer model, the spectral energy distribution (SED) are constructed from multi-wavelength photometric and IRAS-LRS spectral data which provides the luminosity, optical depth, and gas massloss rate (MLR) of the object to be 9600 ± 500 L , 9.1 ± 0.6 at 0.55 µm and 1.0×10 −6 M yr −1 , respectively. The current mass of the object infers in the range 1.0−1.5M assuming solar metallicity. Notably, the temporal variation of atomic and molecular features (e.g., TiO, Na I, Ca I, CO, H 2 O) over the pulsation cycle of the OH/IR star illustrates the sensitivity of the spectral features to the dynamical atmosphere as observed in pulsating AGB stars.

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“…The details about the instruments, observations and data reduction can be found in Do et al (2015) and Støstad et al (2015) for NIFS, and Vernet et al (2011) and Gonneau et al (2020) for X-shooter. We use SIMBAD to remove known supergiants, Mira variables and OH/IR stars of the X-shooter library from our study as they behave differently than normal giants (Lançon & Wood 2000;Ghosh et al 2018). The sample size reduces to 240 stars.…”

Section: Sample Selectionmentioning

confidence: 99%

New Temperature and Metallicity Scale of Cool Giants from K-band Spectra

Ghosh,

Ojha,

Ninan

2020

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We present here quantitative diagnostic tools for cool giants that employ low-resolution near-infrared spectroscopy in the K-band for stellar population studies. In this study, a total of 260 cool giants (177 stars observed with X-shooter and 83 stars observed with NIFS) are used covering a wider metallicity range than in earlier works. We measure equivalent widths of some of the selected important K-band spectral features like Na I, Fe I and 12 CO after degrading the spectral resolution (R∼ 1200) to investigate the spectral behavior with fundamental parameters (e.g. effective temperature and metallicity). We derive empirical relations to measure effective temperature using the 12 CO first-overtone band at 2.29 µm and 2.32 µm and show a detailed quantitative metallicity dependence of these correlations. We find that the empirical relations based on solar-neighborhood stars can incorporate large uncertainty in evaluating T ef f for metal-poor or metal-rich stars. Furthermore, we explore all the spectral lines to establish the empirical relation with metallicity and find that the quadratic fit of the combination of Na I and 12 CO at 2.29 µm lines yields a reliable empirical relation at [F e/H] ≤ -0.4 dex, while a linear fit of any line offers a good metallicity scale for stars having [F e/H] ≥ 0.0 dex.

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Phase-dependent Photometric and Spectroscopic Characterization of the MASTER-Net Optical Transient J212444.87+321738.3: An Oxygen-rich Mira

Cited by 7 publications

References 88 publications

TIFR Treasures for Astronomy from Ground to Space

TIFR Treasures for Astronomy from Ground to Space

Spectroscopic and photometric monitoring of a poorly known high-luminous OH/IR star: IRAS 18278+0931

New Temperature and Metallicity Scale of Cool Giants from K-band Spectra

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