Near-infrared studies of V5558 Sgr: an unusually slow nova with multiple outbursts

Das, Ramkrishna; Banerjee, D. P. K.; Nandi, A.; Ashok, N. M.; Mondal, Soumen

doi:10.1093/mnras/stu2488

Cited by 9 publications

(4 citation statements)

References 34 publications

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“…Following Das et al (2015) and Banerjee et al (2018), we also use an independent approach with the additional benefit that it allows the simultaneous estimates of the the extinction and distance, by using the distance-dependence of the extinction towards the nova, and the absolute magnitude derived from the Maximum Magnitude Rate of Decline (MMRD) relationship (Cohen 1985, and references therein). The extinction towards the nova, over a 5 arc-minute field (Marshall et al 2006), is plotted in Fig.…”

Section: Extinction and Distance Estimatesmentioning

confidence: 99%

Optical and near-infrared spectroscopy of Nova V2891 Cygni: evidence for shock-induced dust formation

Kumar¹,

Srivastava

Banerjee

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present multi-epoch optical and near-infrared observations of the highly reddened, Fe ii class slow nova V2891 Cygni. The observations span 15 months since its discovery. The initial rapid brightening from quiescence, and the presence of a ∼35 day long pre-maximum halt, is well documented. The evidence that the current outburst of V2891 Cyg has undergone several distinct episodes of mass ejection is seen through time-varying P Cygni profiles of the O i 7773 Å line. A highlight is the occurrence of a dust formation event centred around ∼+273d, which coincides with a phase of coronal line emission. The dust mass is found to be ∼0.83 − 1.25 × 10−10 M⊙. There is strong evidence to suggest that the coronal lines are created by shock heating rather than by photoionization. The simultaneous occurrence of the dust and coronal lines (with varying velocity shifts) supports the possibility that dust formation is shock-induced. Such a route for dust formation has not previously been seen in a nova, although the mechanism has been proposed for dust formation in some core-collapse supernovae. Analysis of the coronal lines indicates a gas mass and temperature of 8.35–8.42 × 10−7 M⊙ and ∼(4.8 − 9.1) × 105 K respectively, and an overabundance of aluminium and silicon. A Case B analysis of the hydrogen lines yields a mass of the ionized gas of (8.60 ± 1.73) × 10−5 M⊙. The reddening and distance to the nova are estimated to be E(B − V) = 2.21 ± 0.15 and d = 5.50 kpc respectively.

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Section: Extinction and Distance Estimatesmentioning

confidence: 99%

Optical and near-infrared spectroscopy of Nova V2891 Cygni: evidence for shock-induced dust formation

Kumar¹,

Srivastava

Banerjee

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The recent addition to the list of hybrid novae, namely, V5558 Sgr (Das et al 2015) and V5588 Sgr (Munari et al 2015) suggests that the transition between FeII and He/N class in novae may be more frequent than was believed in earlier years.…”

Section: A Possible Case Of Hybrid Novamentioning

confidence: 99%

IR STUDY OF NOVA V2468 Cyg FROM EARLY DECLINE TO THE CORONAL PHASE

Raj

Ashok

Rudy

et al. 2015

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We present infrared spectroscopic and photometric observations of the nova V2468 Cyg covering the period from 2008 March 13 till 2008 November 11. The JHK spectra of the object have been taken from the Mount Abu Infrared Observatory using the Near-Infrared Imager/Spectrometer. Spectra from 0.8-5.2 µm are also presented that were obtained using the NASA Infrared Telescope Facility and the SPEX instrument. The spectra are dominated by strong H i lines from the Brackett and Paschen series, Fe ii, O i and C i lines in the initial days, typical of an Fe II type nova. The lines were broader in the period immediately after outburst with measured FWHM of 1800-2300 km s −1 for the Paβ and Brγ lines. These values narrowed to 1500-1600 km s −1 by 12 days from outburst. The spectra showed prominent He i lines at 1.0830 and 2.0581 µm together with H i and O i emission features after 36 days from outburst. Our IR observations show the comparatively broad emission lines, the rapid development of the spectrum to higher ionization, the early appearance of coronal lines, and the absence of dust emission, all features that indicate the hybrid nature of the nova. This is perhaps the most extensively observed example of a probable Fe IIb type nova at the infrared wavelengths. We also notice a short lived emission line of Fe II at 2.0888µm which was present between April 9, 2008 to May 9, 2008. No dust emission is seen from the nova ejecta. We have also estimated the range for the ejecta mass in V2468 Cyg to be 3 × 10 −6 -10 −5 M ⊙ .

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“…For e.g. a temperature of 1615K was detected in the Fe II nova V476 Scuti (Das et al 2013), which might have eluded detection had the observation been untimely since the dust rapidly cooled to 1040K within 24 days. The first dust detection in nova V339 Del was at 1637K (Evans et al 2016), temperatures in the range 1300-1700K were estimated in V1280 Sco at different stages of the dust evolution ) while the dust in the classical nova V2326 Cyg condensed at a temperature 1410 ± 15 K (Lynch et al 2008).…”

Section: 315mentioning

confidence: 99%

Near-infrared and optical studies of the highly obscured nova V1831 Aquilae (Nova Aquilae 2015)

Banerjee

Srivastava

Ashok

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Near Infrared (NIR) and optical photometry and spectroscopy are presented for the nova V1831 Aquilae, covering the early decline and dust forming phases during the first ∼90 days after its discovery. The nova is highly reddened due to interstellar extinction. Based solely on the nature of NIR spectrum we are able to classify the nova to be of the Fe II class. The distance and extinction to the nova are estimated to be 6.1 ± 0.5 kpc and A v ∼ 9.02 respectively. Lower limits of the electron density, emission measure and ionized ejecta mass are made from a Case B analysis of the NIR Brackett lines while the neutral gas mass is estimated from the optical [OI] lines. We discuss the cause for a rapid strengthening of the He I 1.0830 µm line during the early stages. V1831 Aql formed a modest amount of dust fairly early (∼ 19.2 days after discovery); the dust shell is not seen to be optically thick. Estimates are made of the dust temperature, dust mass and grain size. Dust formation commences around day 19.2 at a condensation temperature of 1461 ± 15 K, suggestive of a carbon composition, following which the temperature is seen to gradually decrease to 950K. The dust mass shows a rapid initial increase which we interpret as being due to an increase in the number of grains, followed by a period of constancy suggesting the absence of grain destruction processes during this latter time. A discussion is made of the evolution of these parameters, including certain peculiarities seen in the grain radius evolution.

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Near-infrared studies of V5558 Sgr: an unusually slow nova with multiple outbursts

Cited by 9 publications

References 34 publications

Optical and near-infrared spectroscopy of Nova V2891 Cygni: evidence for shock-induced dust formation

Optical and near-infrared spectroscopy of Nova V2891 Cygni: evidence for shock-induced dust formation

IR STUDY OF NOVA V2468 Cyg FROM EARLY DECLINE TO THE CORONAL PHASE

Near-infrared and optical studies of the highly obscured nova V1831 Aquilae (Nova Aquilae 2015)

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