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we present here l and m band results on v4332 sgr . recent studies of v4332 sgr have shown that it is an interesting object and the present results further support this view . v4332 sgr erupted in 1994 in a nova - like outburst with an outburst amplitude of 9.5 magnitude in the visible region . there was only one detailed study of the object during its outburst ( martini et al . 1999 ) which showed that its eruption was different from that of a classical nova or other classes of eruptive variables . interest in the object has been rekindled because of the recent outburst of v838 mon which drew considerable attention due to its light - echo ( munari et al . 2002 ; bond et al . it is believed that v838 mon , v4332 sgr and m31 rv ( a red - variable which exploded in m31 in 1988 ; rich et al . 1989 ) could be members of a new class of eruptive objects ( munari et al . 2002 ; bond et al . 2003 , kimeswenger et al . the cause of the outburst in these objects does not appear to be satisfactorily explained by conventional mechanisms . thus new theories have been proposed viz . a scenario involving the merger of main sequence stars ( soker @xmath2 tylenda , 2003 ) and a hypothesis invoking planetary - capture by an expanding star to explain the eruption ( retter @xmath2 marom , 2003 ) . the present data indicate that the second mechanism could be viable in v4332 sgr . recent infrared studies of v4332 sgr have detected several bands of alo at a low rotational temperature of 200 - 300k ( banerjee et al . a considerable change in the spectral energy distribution ( sed ) of the object was seen between 2mass data of 1998 and observations in 2003 indicating the formation of a dust shell between these two epochs ( banerjee et al . 2003 ) . a better estimate of the epoch when the dust actually formed is discussed here . optical spectroscopy of v4332 sgr in 2003 , showed an interesting spectrum dominated by very strong emission in the resonance lines of ki and nai ( banerjee @xmath2 ashok 2004 ) . the sed of the star , derived from optical and ir data , indicated a central star with a black - body temperature of 3250k and an ir excess attributed to a dust component at @xmath3 900k ( banerjee @xmath2 ashok 2004 ) . observations were done using the 3.8 m uk infrared telescope ( ukirt ) . spectroscopy was done using the ukirt imaging spectrometer ( uist ) , which uses different grisms to cover the 1.4 - 5 micron range . @xmath4 ( 3.77 @xmath0 m ) and @xmath5 ( 4.68 @xmath0 m ) band photometry - not available earlier for v4332 sgr - was also done using uist . flat - fielding , spectral calibration and other reduction procedures were done on the same lines as our earlier @xmath6 study of v4332 sgr ( banerjee et al . 2003).the log of the observations and the observed @xmath7 magnitudes of v4332 sgr are given in table 1 . figure 1 shows the spectrum - the a - x bands of alo in the @xmath8 band , reported earlier ( banerjee et al . 2003 ) are seen prominently in the present spectrum also but are not discussed here . a remarkable feature - never seen before in a nova - like object - is the deep , solid - state 3.05 @xmath0 m water - ice band formed due to the o - h stretching mode . at very low temperatures , atoms and molecules can collide and adhere to a dust grain to produce an ice mantle on the surface . atoms can migrate from one site to another on the mantle to form a molecule - water ice is believed to form this way with h atoms combining with an o atom . the presence of cold water - ice around v4332 sgr is extremely unexpected since the ejecta of classical novae generally evolve to high temperatures of @xmath3 10@xmath9k ( the coronal phase ) . following a standard procedure , we have obtained the optical depth plot of the ice feature by fitting a polynomial to the continuum around it ( gibb et al . the depth of the ice feature below this continuum was found and converted to an optical depth . the optical depth plot is shown in figure 2 . the 3.05 @xmath0 m feature was compared with laboratory data for the optical depth of water - ice at different temperatures ( 10 , 30 , 50 , 120 and 160k ) taken from the leiden database for ice analogslab/ ] . from a @xmath10@xmath11 test to the observed and model data , we find that the 50k data gives the smallest value of @xmath10@xmath11 . the 30k data also gives a comparable value of @xmath10@xmath11 thus suggesting a low temperature of @xmath330 - 50k for the water ice . an extended red wing between 3.3 - 3.8 @xmath0 m , which is not well fitted by the models , is seen in the observed data . this extended ice wing is also seen in several water ice detections but the species responsible for it is unidentified ( gibb et al . 2004 ) . from figure 2 , the column density of the water - ice @xmath12 was calculated using @xmath12 = @xmath13@xmath14d@xmath15/@xmath16 , where @xmath16 is the the band strength for water - ice with a laboratory measured value of @xmath16 = 20@xmath1710@xmath18 cm molecule@xmath19 . while carrying out the integration , we have assumed that the missing data points around 2.65 @xmath0 m ( due to atmospheric cutoff ) , are represented by the data points of the 50k laboratory model in that region . we obtain a value of @xmath13@xmath14d@xmath15 = 362@xmath2027 cm@xmath19 leading to @xmath12 = ( 1.81@xmath200.13)@xmath1710@xmath22 @xmath23 - this value may be used in case of future detection of other ices ( co@xmath24 , ch@xmath25oh , ch@xmath26 etc . ) in v4332 sgr to get a better understanding of the ice composition .    another rare feature seen in v4332 sgr is the fundamental band ( @xmath15 = 1 - 0 ) of @xmath1co at 4.67 @xmath0 m in emission . there appear to be only a few other detections of the co fundamental in emission - mostly towards ysos and herbig aebe stars ( e.g. blake @xmath2 boogert 2004 ; pontoppidan et al . in a few novae , emission in the co first overtone bands has been seen ( rudy et al . 2003 - table 3 therein ; evans et al . 1996 ) but the detection of the fundamental band appears rare ( lynch et al . 1997 ) . the expanded co ro - vibrational spectrum in v4332 sgr is shown in figure 3 . individual branch lines from p@xmath27 to p@xmath28 and r@xmath29 to r@xmath28 are clearly seen . the lines are not resolved at their intrinsic width at the observed resolution of 1000 . a simple model for the @xmath1co emission was computed assuming lte conditions with the level populations proportional to ( 2j+1)e@xmath30 where b and j are the rotational constant for co and the rotational quantum number respectively ; t is the temperature . the strength of each p or r branch line was then obtained using the transition probabilities for the lines given by goorvitch ( 1994 ) . the line positions were also taken from goorvitch ( 1994 ) . the model spectrum thus obtained was convolved with a gaussian instrument function of fwhm 0.046 @xmath0 m ( i.e. a resolution of 1000 ) . from the model fits , it is difficult to constrain the temperature of the gas too accurately , but a relatively low temperature of @xmath3300 - 400k is suggested . this could possibly be the reason for the absence in v4332 sgr of the first overtone co bands at 2.3 - 2.45@xmath0 m which need a higher temperature for excitation . these bands have been modeled to have a temperature in the range 2500 - 4500k in novae ( rudy et al . 2003 ; evans et al . 1996 ) . further , the strong presence of alo bands in v4332 sgr in the same spectral region as the co first overtone bands , makes it difficult to draw definite conclusions on the absence / presence of the latter . a better estimate for the co temperature than that derived here would require modeling based on higher resolution spectra ( e.g. blake @xmath2 boogert 2004 ; pontoppidan et al . 2002 ) . the detection of water ice at 30 - 50k in v4332 sgr is very intriguing since such a low temperature component is not expected in novae ejecta . based on the recent comprehensive survey ( gibb et al . 2004 and references therein ) , most water - ice detections are seen towards embedded ysos / protostars . such objects are known to have circumstellar disks ( csds ) around them . in addition , water - ice has also been seen in herbig aebe stars and a few t tauri stars ( creech eakman et al . 2002 ; meeus et al . 2001 , gibb et al . these are all young objects observationally known to possess csds . furthermore , all the gaseous components of v4332 sgr are seen in emission i.e. the ki / nai , co , alo and tio lines ( banerjee @xmath2 ashok 2004 ; banerjee et al . these species are at a low temperature ( 200k for alo ; a low excitation temperature is also implied for the ki / nai lines which need only @xmath3 1.5 - 2ev for excitation ) . if the region in which these species exist were to be a shell surrounding the central 3250k star of v4332 sgr ( banerjee @xmath2 ashok 2004 ) , the relatively cold gas of these species should lead to lines in absorption . such is not the case . instead , if the various species are in a disk , their lines can be expected in emission . furthermore , in the case of a disk , the central star would also be observable since it will be unobscured ( some obscuration could occur depending on the orientation and thickness of the disk ) . such is the case in v4332 sgr where the continuum from the central star is clearly seen . additional support for a csd is the infrared excess seen in v4332 sgr ( banerjee @xmath2 ashok 2004 ) . this ir excess can be attributed to dust in the disk and not in a shell around the star since the dust shell would obscure the visible radiation of the star . a similar reasoning is used to explain the ir excess in t tauri stars . it is also relevant to note that many of the known co fundamental detections are in disk - dominated herbig ae stars ( blake @xmath2 boogert 2004 ) . the considerable width of the ki lines in v4332 sgr was also shown to be consistent with line broadening arising from rotational motion of gas in a disk ( banerjee @xmath2 ashok 2004 ) . an additional signature that v4332 sgr has pre - existing matter around it at the time of the 1994 outburst comes from the high - resolution h@xmath31 profiles of the object taken shortly after its outburst . these profiles ( figure 8 of martini et al . 1999 ) show a deep absorption trough at the center which could be caused by absorption by pre - existing matter . therefore , many of the observed characteristics of v4332 sgr support the existence of a csd around the object . however , it is difficult to rule out the possibility of the matter being in clumps instead of a disk . it may be pointed out that the maximum value of @xmath14 @xmath3   1 of the ice feature ( figure 2 ) , would imply a large extinction of a@xmath32 @xmath3 14 magnitudes towards the central star , had the 3.05@xmath0 m absorption arisen because of cold , intervening matter in the line of sight ( as in embedded ysos in dark clouds ; whittet 1992 ) . as the central star appears unobscured ( v= 17.52 , banerjee @xmath2 ashok 2004 ) , the 3.05@xmath0 m feature could instead be caused by ice in the csd viewed against the ir flux from dust in the disc leading to the absorption feature . it was earlier shown that the @xmath6 fluxes of v4332 sgr changed considerably between 2mass observations of may , 1998 ( @xmath33 = 12.1 , @xmath34 = 11.6 , @xmath35 = 10.992 ) and observations of june , 2003 ( @xmath33 = 13.25 , @xmath34 = 11.986 , @xmath35 = 10.023 ; banerjee et al . while the 2 mass data showed no ir excess and was well modeled by a 3250k blackbody , the 2003 data showed a composite sed of a blackbody component at 900k ( due to newly formed dust ) and a weakening of the 3250k component due to obscuration by dust . however , it was not possible to establish with accuracy at which stage between 1998 and 2003 the dust formed . data from the denis survey is now available and this shows that in september , 1999 v4332 sgr had ir magnitudes of @xmath33= 12.46 and @xmath35 = 10.65 ( denis did not observe in @xmath34 band ) . a comparison between 2mass and denis @xmath36 magnitudes clearly shows the ir flux increasing towards longer wavelengths indicating that dust formation had begun by the denis epoch . the formation of dust therefore took place at t@xmath37 @xmath3 5.5 years after the outburst of february 1994 . this is much larger than the typical timescale of 50 - 100 days for dust formation in classical novae . the difficulty in having a large dust - condensation time in novae is that the density in the ejecta decreases to a low level - due to expansion - that does not favor dust - formation . the density @xmath38 in the ejecta of novae that form dust is in the range 10@xmath39 to 10@xmath40g@xmath41 ( gehrz 1988 ) . in v4332 sgr , the electron density n@xmath42 after @xmath3 2 - 3 months from the outburst was estimated to be 10@xmath43 @xmath41 ( martini et al . 1999 ) . a geometric dilution for the expanding ejecta matter may be a reasonable assumption i.e n@xmath42 @xmath31 1/r@xmath11 provided the ejecta expands freely , unhindered by pre - existing matter . @xmath31 1/r@xmath11 , after a time of 5.5yr , n@xmath42 should have evolved to @xmath3 10@xmath44 @xmath41 giving a value of @xmath38 = 10@xmath18 - 10@xmath45g@xmath41 . such a low value of @xmath38 appears unfavorable for dust formation . it therefore appears that dust formation may not have occured per se in the ejecta of the 1994 outburst . it is likely that the ejecta , after a stage of free expansion , could have impinged on pre - existing matter around v4332 sgr - sufficiently far from the star - thereby heating it and giving rise to the observed emission at present from different species . this could be one possible scenario to explain the large observed time for the formation of dust . in a connected aspect , we note that the present @xmath4 , @xmath5 data of figure 1 , shows the continuum peaking at @xmath3 4.4@xmath0 m indicating a lower , dust temperature than the 900k that was inferred earlier . however , mid / far - ir observations planned on the spitzer telescope should give more definite information on the dust temperature . more than a hundred stars with planets ( swps ) are known today and in @xmath315@xmath46 of these the planetary companion is unexpectedly close to the host star ( @xmath47 0.05 au ) . the orbits of such short - period planets around sun - like stars can be unstable because of tidal dissipation and they can be subsequently consumed by the host stars ( sandquist et al . 2002 ; rasio et al . more evolved stars are also capable of swallowing their planets as they expand ( siess @xmath2 livio 1999 ) . the viability of planetary ingestion is observationally supported by the enhanced metallicity seen in many swps - and the presence of li isotopes in one of them - suggesting that planetary material has been accreted by the host star in the past ( santos et al . 2000 ; gonzalez et al . 2001 ; israelian et al . 2003 ) . in particular context of v4332 sgr type of objects , retter and marom ( 2003 ) have explained the multi - peak light curve of v838 mon as due to an expanding star ingesting its planets . we have shown that there is considerable evidence that v4332 sgr is surrounded by a cold , dusty disk . it is precisely in such an environment that planets are believed to be born from the coagulation and accretion of solid ice and dust particles ( lissauer 1993 ) . therefore , while it may appear speculative , it is not entirely unlikely that a planet existed around v4332 sgr and its infall led to the outburst . the plausibility of this scenario is strengthened since other conventional mechanisms - such as a thermo - nuclear runaway on a white dwarf surface ( invoked for classical , recurrent , symbiotic novae ) or a final helium shell flash ( invoked for a born - again agb star ) - fail to explain the pre- and post - outburst properties of v4332 sgr or similar objects . it was shown ( retter @xmath2 marom 2003 ) in the analysis for v838 mon , that the gravitational energy released by a 1m@xmath48 planet falling into a solar - mass star is 4@xmath1710@xmath49l@xmath50 . the outburst luminosity of v4332 sgr is difficult to estimate as the distance @xmath51 to the object is very uncertain . using an estimate of @xmath51 = 300 pc ( martini et al . 1999 ) we have shown that the star has a quiescent luminosity of   0.3@xmath52@xmath50 ( banerjee et al . a 9.5 magnitude brightening at outburst would yield an outburst luminosity of @xmath3 2@xmath1710@xmath53l@xmath50 . this is lower than the predicted energy release for the capture of a 1m@xmath48 planet but could be made consistent by revising the distance ( the current distance estimate to v838 mon has been revised upwards by a factor of nearly 10 from its first estimate ) , invoking a smaller mass for the captured planet or that a large part of the released gravitational energy has gone into expansion of the stellar envelope ( retter @xmath2 marom 2003 ) rather than visible radiation . however , we feel there are many aspects about the nature of v4332 sgr that are still unclear and there is scope for alternative models , apart from that proposed here , to explain its outburst . research at the prl is funded by the dept . of space , govt . of india . we thank the ukirt service program for observation time covering a part of these observations . ukirt is operated by the jac , hawaii on behalf of the uk pparc . we are grateful to the referee for several helpful comments . cccccc + date(ut ) & band & resol- & integration & standard & magni- + & & ution & time(s ) & star & tude + & & & & & + spectroscopy & & & & & + 2003 sept . 5.294 & m & 1000 & 312 & bs 6998 & + 2003 sept . 5.359 & kl & 700 & 360 & bs 6998 & + 2003 sept . 5.328 & short l & 650 & 720 & bs 6969 & + 2004 april 15.606 & hk & 500 & 720 & bs 7038 & + 2004 april 29.642 & long l & 1150 & 320 & bs 6998 & + & & & & & + photometry & & & & & + 2003 sept . 5.262 & l & & 252 & hd 161743 & 7.23 @xmath20 0.025 + 2003 sept . 5.276 & m & & 322 & hd 161743 & 6.10 @xmath20 0.03 +   +
l and m band observations of the nova - like variable v4332 sgr are presented . 
 two significant results are obtained viz . 
 the unusual detection of water ice at 3.05@xmath0 m and the fundamental band of @xmath1co at 4.67@xmath0 m in emission . 
 the ice feature is a first detection in a nova - like variable while the co emission is rarely seen in novae . 
 these results , when considered together with other existing data , imply that v4332 sgr could be a young object surrounded by a circumstellar disc containing gas , dust and ice . 
 the reason for a nova - like outburst to occur in such a system is unclear . 
 but since planets are believed to form in such disks , it appears plausible that the enigmatic outburst of v4332 sgr could be due to a planetary infall . 
 we also give a more reliable estimate for an epoch of dust formation around v4332 sgr which appears to have taken place rather late in 1999 - nearly five years after its outburst .