arXiv subjects

R. Tylenda

Publications and source records attributed to R. Tylenda.

At least 19 recordsLinked to original sources

arXiv2020

Molecular remnant of Nova 1670 (CK Vulpeculae). II. A three-dimensional view on the gas distribution and velocity field

CK Vul is the remnant of an energetic eruption known as Nova 1670 that is thought to be caused by a stellar merger. The remnant is composed of (1) a large hourglass nebula of recombining gas (of 71\arcsec size), very similar to some classical planetary and pre-planetary nebulae (PPNe), and (2) of a much smaller and cooler inner remnant prominent in millimeter-wave emission from molecules. We investigate the three-dimensional spatio-kinematic structure of both components. The analysis of the hourglass structure yields a revised distance to the object of >2.6 kpc, at least 3.7 times greater than so far assumed. At this distance, the stellar remnant has a bolometric luminosity >12 L$_{\odot}$ and is surrounded by molecular material of total mass >0.8 M$_{\odot}$ (the latter value has a large systematic uncertainty). We also analyzed the architecture of the inner molecular nebula using ALMA observations of rotational emission lines obtained at subarcsecond resolution. We find that the distribution of neutral and ionized gas in the lobes can be reproduced by several nested and incomplete shells or jets with different velocity fields and varying orientations. The analysis indicates that the molecular remnant was created in several ejection episodes, possibly involving an interacting binary system. We calculated the linear momentum ($\approx$10$^{40}$ g cm s$^{-1}$) and kinetic energy ($\approx$10$^{47}$ erg) of the CK Vul outflows and find them within the limits typical for classical PPNe. Given the similarities of the CK Vul outflows to PPNe, we suggest there may CK Vul analogs among wrongly classified PPNe with low intrinsic luminosities, especially among PPNe with post-red-giant-branch central stars.

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arXiv2020

Molecular remnant of Nova 1670 (CK Vulpeculae): I. Properties and enigmatic origin of the gas

CK Vul erupted in 1670 and is considered a stellar-merger candidate. Its remnant contains a molecular component of surprisingly rich composition. We present interferometric line surveys with subarcsec resolution with ALMA and SMA. The observations provide interferometric maps of molecular line emission at frequencies between 88 and 243 GHz that allow imaging spectroscopy of more than 180 transitions of 26 species. We present, classify, and analyze the different morphologies of the emission regions displayed by the molecules. We also perform a non-LTE radiative-transfer analysis of emission of most of the observed species, deriving temperatures and column densities in five parts of the nebula. Non-LTE effects are clearly seen in complex species including methanol absorption against the CMB. The temperatures are 17 K in the inner remnant and 14 K in the extended lobes. We find total (hydrogen plus helium) densities in the range of $10^4-10^6$ cm$^{-3}$. The column densities provide relative abundance patterns in the remnant which currently are not understood. Attempts to derive elemental abundances within the assumption of a chemical equilibrium give only loose constraints on the CNO elements. That the formation of many of the observed molecules requires a major involvement of circumstellar shocks remains the preferred possibility. The molecular gas could have formed 350 yr ago or more recently. The molecules are well shielded from the interstellar radiation field by the circumstellar dust. Their presence alone indicates that the unobservable central star cannot be a hot object such as a white dwarf. This excludes some of the proposed scenarios on the nature of CK Vul. The general characteristics of the molecular environment of CK Vul derived in this study resemble quite well those of some pre-planetary nebulae and AGB stars, most notably that of OH231.8.

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arXiv2019

Elemental abundances in the remnant of the ancient eruption of CK Vulpeculae

CK Vul or Nova 1670 is an enigmatic eruptive object which underwent a stellar-merger event recorded by seventeenth-century observers. Its remnant was recently recovered at submillimeter wavelengths, revealing gas of an extraordinary isotopic composition indicative of past processing in the CNO cycles and partial He burning. Here, we present long-slit optical spectra of the remnant acquired with X-shooter at the Very Large Telescope at an unprecedented sensitivity and spectral coverage. The spectra cover features of key elements - including H, He, C, N, and O - at ionization degrees I-III. A classical analysis of the spectra allows us to identify several spatio-kinematic components in the probed part of the nebula at electron temperatures of 10-15 kK and densities of 200-600 cm$^{-3}$. We find that the nebula is most likely excited by shocks rather than by direct radiation of the stellar remnant. We provide a detailed analysis of the elemental abundances in the remnant and find that helium is twice more abundant than in the Sun. Nitrogen is also overabundant with a N/O ratio ten times larger than the solar one. These anomalous abundances strongly indicate that the observed gas was processed in CNO cycles of H burning, consistent with the submillimeter studies. Additionally, sub-solar abundances of heavier elements, such as Ne, S, and Ar, suggest that the progenitor of CK Vul was formed from material poorer in metals than the Sun and was therefore an old stellar system before the 1670 eruption.

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arXiv2018

Submillimeter-wave emission of three Galactic red novae: cool molecular outflows produced by stellar mergers

Red novae are optical transients erupting at luminosities typically higher than those of classical novae. Their outbursts are believed to be caused by stellar mergers. We present millimeter/submillimeter-wave observations with ALMA and SMA of the three best known Galactic red novae, V4332 Sgr, V1309 Sco, and V838 Mon. The observations were taken 22, 8, and 14 yr after their respective eruptions and reveal the presence of molecular gas at excitation temperatures of 35-200 K. The gas displays molecular emission in rotational transitions with very broad lines (full width $\sim$400 km\s). We found emission of CO, SiO, SO, SO$_2$ (in all three red novae), H$_2$S (covered only in V838 Mon) and AlO (present in V4332 Sgr and V1309 Sco). No anomalies were found in the isotopic composition of the molecular material and the chemical (molecular) compositions of the three red novae appear similar to those of oxygen-rich envelopes of classical evolved stars (RSGs, AGBs, post-AGBs). The minimum masses of the molecular material that most likely was dispersed in the red-nova eruptions are 0.1, 0.01, and 10$^{-4}$ M$_{\odot}$ for V838 Mon, V4332 Sgr, and V1309 Sco, respectively. The molecular outflows in V4332 Sgr and V1309 Sco are spatially resolved and appear bipolar. The kinematic distances to V1309 Sco and V4332 Sgr are 2.1 and 4.2 kpc, respectively. The kinetic energy stored in the ejecta of the two older red-nova remnants of V838 Mon and V4332 Sgr is of order $10^{46}$ erg, similar to values found for some post-AGB (pre-PN) objects whose bipolar ejecta were also formed in a short-duration eruption. Our observations strengthen the link between these post-AGB objects and red novae and support the hypothesis that some of the post-AGB objects were formed in a common-envelope ejection event or its most catastrophic outcome, a merger.

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arXiv2017

Organic molecules, ions, and rare isotopologues in the remnant of the stellar-merger candidate, CK Vulpeculae (Nova 1670)

CK Vul is a star whose outburst was observed in 1670-72. A stellar-merger event was proposed to explain its ancient eruption. Aims: We aim to investigate the composition of the molecular gas recently discovered in the remnant of CK Vul. Methods: We observed millimeter and submillimeter-wave spectra of CK Vul using the IRAM 30m and APEX telescopes. Radiative-transfer modeling of the observed molecular features was performed to yield isotopic ratios for various elements. Results: The spectra of CK Vul reveal a very rich molecular environment of low excitation ($T_{\rm ex} \lesssim$12 K). Atomic carbon and twenty seven different molecules, including two ions, were identified. They range from simple diatomic to complex polyatomic species of up to 7 atoms large. The chemical composition of the molecular gas is indicative of carbon and nitrogen-driven chemistry but oxides are also present. Additionally, the abundance of F may be enhanced. The spectra are rich in isotopologues that are very rare in most known sources. All stable isotopes of C, N, O, Si, and S are observed and their isotopic ratios are derived. Conclusions: The composition of the remnant's molecular gas is most peculiar and gives rise to a very unique millimeter and submillimeter spectrum. The observation of ions and complex molecules suggests the presence of a photoionizing source but its nature (a central star or shocks) remains unknown. The elemental and isotopic composition of the gas cannot be easily reconciled with standard nucleosynthesis but processing in hot CNO cycles and partial He burning can explain most of the chemical peculiarities. The isotopic ratios of CK Vul are remarkably close to those of presolar nova grains but the link of Nova 1670 to objects responsible for these grains is unclear.

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arXiv2016

Evolution of the stellar-merger red nova V1309 Scorpii: SED analysis

One very important object for understanding the nature of red novae is V1309 Sco. Its pre-outburst observations showed that, before its red-nova eruption in 2008, it was a contact binary quickly evolving to the merger of the components. It thus provided us with a direct evidence that the red novae result from stellar mergers. We analyse the spectral energy distribution (SED) of the object and its evolution with time. From various optical and infrared surveys and observing programmes carried out with OGLE, HST, VVV, Gemini South, WISE, Spitzer, and Herschel we constructed observed SED in 2010 and 2012. Some limited data are also available for the red-nova progenitor in 2007. We analyse the data with our model of a dusty envelope surrounding a central star. Dust was present in the pre-outburst state of V1309 Sco. Its high temperature (900-1000 K) suggests that this was a freshly formed dust in a presumable mass-loss from the spiralling-in binary. Shortly after its 2008 eruption, V1309~Sco became almost completely embedded in dust. The parameters (temperature, dimensions) of the dusty envelope in 2010 and 2012 evidence that we then observed matter lost by the object during the 2008 outburst. Its mass is at least $10^{-3}\,M_\odot$. The object remains quite luminous, although since its maximum brightness in September 2008, it has faded in luminosity by a factor of ~50 (in 2012). Far infrared data from Herschel reveal presence of a cold (~30 K) dust at a distance of a few thousand AU from the object. This conclusion could be verified by submillimeter interferometric observations.

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arXiv2015

VLT/UVES spectroscopy of V4332 Sagittarii in 2005: The best view on a decade-old stellar-merger remnant

V4332 Sgr is a red transient (red nova) whose eruption was observed in 1994. The remnant of the eruption shows a unique optical spectrum: strong emission lines of atoms and molecules superimposed on an M-type stellar spectrum. The stellar-like remnant is presumably embedded in a disc-like dusty envelope seen almost face-on. The observed optical spectrum is assumed to result from interactions of the central-star radiation with dust and gas in the disc and outflows initiated in 1994. We reduced and measured a high-resolution (R = ~40 000) spectrum of V4332 Sgr obtained with VLT/UVES in April/May 2005. The spectrum comes from the ESO archives and is the best quality spectrum of the object ever obtained. We identified and measured over 200 emission features belonging to 11 elements and 6 molecules. The continuous, stellar-like component can be classified as ~M3. The interstellar reddening was estimated to be 0.35 < E(B-V) < 0.75. From radial velocities of interstellar absorption features in the NaI D lines, we estimated a lower limit of ~5.5 kpc to the distance of V4332 Sgr. The spectrum of V4332 Sgr considerably evolved between 2005 and 2009. The object significantly faded in the optical, which resulted from cooling of the main remnant by 300-350 K, corresponding to its spectral-type change from M3 to M5-6. The object increased in luminosity by ~50%, however, implying a significant expansion of its dimensions. Most of the emission features seen in 2005 significantly faded or even disappeared from the spectrum of V4332 Sgr in 2009. These resulted from fading of the optical central-star radiation and a decrease of the optical thickness of the cirumstellar matter. V4332 Sgr bears several resemblances to V1309 Sco, which erupted in 2008. This can indicate a similar nature of the eruptions of the two objects. The outburst resulted from merger of a contact binary in V1309 Sco.

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arXiv2013

Optical spectropolarimetry of V4332 Sagittarii

The eruption of V4332 Sgr was observed in 1994. During the outburst, the object became extremely red, so it has been considered as to belong to red transients of the V838 Mon type. Optical spectroscopy obtained a few years after the eruption showed a faint M-type stellar spectrum underlying numerous molecular and atomic emission features. It has recently been suggested that the central object in V4332 Sgr is now hidden in a dusty disc and that the photospheric spectrum of this object observed in the optical results from scattering of the radiation of the central star on dust grains in the circumstellar matter. Recent polarimetric photometry has shown that the optical radiation of the object is indeed strongly polarized. We present and analyse our spectropolarimetric observations of V4332 Sgr obtained with the VLT in the optical region. The optical continuum of V4332 Sgr is linearly polarized with a typical degree of 16.6%. A clear depolarization is observed in the spectral regions where emission features contribute significantly to the observed flux. The only prominent exception is the CaI 6573 emission line, which is polarized in 21%. The results of our spectropolarimetric observations are in accord with the proposed geometry of the system and the advocated nature of the observed optical spectrum of V4332 Sgr. The continuum is not seen directly but results from scattering on dust within the disc and polar outflow, while most of the gas emission comes from the polar outflow excited by the radiation field of the central source. Additionally, the observed polarization patterns suggest a stratification of the outflow.

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arXiv2013

OGLE-2002-BLG-360: from a gravitational microlensing candidate to an overlooked red transient

OGLE-2002-BLG-360 was discovered as a microlensing candidate by the OGLE-III project. The subsequent light curve however clearly showed that the brightening of the object could not have resulted from the gravitational microlensing phenomenon. We aim to explain the nature of OGLE-2002-BLG-360 and its eruption observed in 2002--2006. The observational data primarily come from the archives of the OGLE project, which monitored the object in 2001--2009. The archives of the MACHO and MOA projects also provided us with additional data obtained in 1995--99 and 2000--2005, respectively. These data allowed us to analyse the light curve of the object during its eruption, as well as the potential variability of its progenitor. In the archives of several infrared surveys, namely 2MASS, MSX, Spitzer, AKARI, WISE, and VVV, we found measurements of the object, which allowed us to study the spectral energy distribution (SED) of the object. We constructed a simple model of a star surrounded by a dusty envelope, which was used to interpret the observed SED. Our analysis of the data clearly shows that OGLE-2002-BLG-360 was most probably a red transient, i.e. an object similar in nature to V838 Mon, whose eruption was observed in 2002. The SED in all phases, i.e. progenitor, eruption, and remnant, was dominated by infrared emission, which we interpret as evidence of dust formation in an intense mass outflow. Since 2009 the object has been completely embedded in dust. We suggest that the progenitor of OGLE-2002-BLG-360 was a binary, which had entered the common-envelope phase a long time (at least decades) before the observed eruption, and that the eruption resulted from the final merger of the binary components. We point out similarities between OGLE-2002-BLG-360 and CK Vul, whose eruption was observed in 1670--72, and this strengthens the hypothesis that CK Vul was also a red transient.

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arXiv2011

High-resolution optical spectroscopy of V838 Monocerotis in 2009

V838 Mon erupted at the beginning of 2002. In the course of the outburst the object evolved to low effective temperatures and declined as a very late M-type supergiant. Among various scenarios proposed to explain the nature of the outburst, the most promising is a stellar merger event. We aim at studying the structure and evolution of the object in the decline from the 2002 eruption. We obtained spectroscopic observations of V838 Mon in January--March 2009 with UVES/VLT. The results are analysed and compared with similar observations obtained in October 2005 with HIRES/Keck. The most striking difference between 2009 and 2005 is a complete absence of the B3V component and of the [FeII] emission lines in 2009. The present spectrum displays only the spectrum of the 2002 eruption remnant. It resembles that of an M6 giant, although the molecular bands in V838 Mon are deeper than those in standard stellar spectra of a similar spectral class. Several atomic lines, which displayed P-Cyg profiles in 2005, are now dominated by pure absorptions. Some of these lines, however, show a narrow emission component, which, as we argue, measures the radial velocity of V838 Mon. The resulting heliocentric velocity is 71 km/s, which very well agrees with the velocity obtained from SiO maser observations. The atomic lines and the molecular bands show very complex kinematics. In some atomic lines and high-excitation molecular bands we observe matter infalling in the object atmosphere. The infall components were already observed in 2005, but were less pronounced and present in fewer lines than in 2009. We argue that the most negative radial velocity components seen in the resonance atomic lines and in the low-excitation molecular bands were formed in the ejecta of the 2002 eruption. The B3V companion most probably became engulfed in an opaque dusty matter of the 2002 V838 Mon ejecta.

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arXiv2011

A molecular cloud within the light echo of V838 Monocerotis

Context. V838 Mon is an eruptive variable, which exploded in 2002. It displayed the most spectacular light echo ever observed. However, neither the origin of the reflecting matter nor the nature of the 2002 outburst have been firmly constrained. Aims. We investigate the nature of the CO radio emission detected in the field of the light echo. In particular, we explore its connection to the echoing dust around V838 Mon. Methods. We observed the echo region in multiple CO rotational transitions. We present and analyse maps of the region obtained in the 12CO(1-0) and (3-2) lines. In addition, deep spectra at several positions were acquired in 12CO(1-0), (2-1), (3-2), and 13CO(1-0), (2-1). Radiative transfer modelling of line intensities is performed for chosen positions to constrain the kinetic temperatures and densities. We derive global parameters (e.g. mass, distance, total column density) of the emitting cloud. Results. We found that a compact molecular cloud is located within the echo region. The molecular emission is physically connected to the dusty environment seen in the optical echo and they both belong to the same translucent cloud. The interstellar nature of the cloud is confirmed by its high mass of 90-150 Msun. We propose that the cloud consists of material remaining after the formation of the cluster to which V838 Mon belongs. This indicates that the eruptive star has young age (3-10 Myr).

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arXiv2011

V1309 Scorpii: merger of a contact binary

Stellar mergers are expected to take place in numerous circumstences in the evolution of stellar systems. In particular, they are considered as a plausible origin of stellar eruptions of the V838 Mon type. V1309 Sco is the most recent eruption of this type in our Galaxy. The object was discovered in September 2008. Our aim is to investigate the nature of V1309 Sco. V1309 Sco has been photometrically observed in course of the OGLE project since August 2001. We analyse these observations in different ways. In particular, periodogram analyses were done to investigate the nature of the observed short term variability of the progenitor. We find out that the progenitor of V1309 Sco was a contact binary with an orbital period of ~1.4 day. This period was decreasing with time. Similarly the light curve of the binary was also evolving, indicating that the system evolved toward its merger. The violent phase of the merger, marked by the systematic brightenning of the object, started in March 2008, i.e. half a year before the outburst discovery. We also investigate the observations of V1309 Sco during the outburst and the decline and show that they can be fully accounted for within the merger hypothesis. For the first time in the literature we show, from direct observations, that contact binaries indeed end up by merging into a single object, as it was suggested in numerous theoretical studies of these systems. Our study also shows that stellar mergers indeed result in eruptions of the V838 Mon type.

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arXiv2011

Strong linear polarization of V4332 Sgr: a dusty disc geometry

The eruption of V4332 Sgr was observed in 1994. During the outburst, the object became extremely red, so it is considered as belonging to luminous red transients of the V838 Mon type. It has recently been suggested that the central object in V4332 Sgr is now hidden in a dusty disc and that the photospheric spectrum of this object observed in the optical results from scattering the central star radiation on dust grains in the disc. One expects significant polarization of the spectrum in this case. We investigate this prediction. We present and analyse polarimetric observations of V4332 Sgr in the V and R photometric bands done with the NOT telescope. The optical light of V4332 Sgr is linearly polarized with a degree of ~26% in the V band and ~11% in R. Discussion of the observed polarization leads us to conclude that the photospheric spectrum observed in V4332 Sgr is probably produced by dust scattering not only in the disc but also in the outflow from the object seen in the emission features.

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arXiv2010

V4332 Sagittarii: A circumstellar disc obscuring the main object

V4332 Sgr experienced an outburst in 1994 whose observational characteristics in many respects resemble those of the eruption of V838 Mon in 2002. It has been proposed that these objects erupted because of a stellar-merger event. Our aim is to derive, from observational data, information on the present (10-15 yrs after the outburst) nature and structure of the object. We present and analyse a high-resolution (R = 21 000) spectrum of V4332 Sgr obtained with the Subaru Telescope in June 2009. Various components (stellar-like continuum, atomic emission lines, molecular bands in emission) in the spectrum are analysed and discussed. We also investigate a global spectral energy distribution (SED) of the object mostly derived from broadband optical and infrared photometry. The observed continuum resembles that of an M6 giant. The emission features (atomic and molecular) are most probably produced by radiative pumping. The observed strengths of the emission features strongly suggest that we only observe a small part of the radiation of the main object responsible for pumping the emission features. An infrared component seen in the observed SED, which can be roughly approximated by two blackbodies of 950 and 200 K, is 50 times brighter than the M6 stellar component seen in the optical. This further supports the idea that the main object is mostly obscured for us. The main object in V4332 Sgr, an M6 (super)giant, is surrounded by a circumstellar disc, which is seen almost edge-on so the central star is obscured. The observed M6 spectrum probably results from scattering the central star spectrum on dust grains at the outer edge of the disc.

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arXiv2009

An analysis of a spectrum of V838 Monocerotis in October 2005

V838 Mon erupted at the beginning of 2002. Among various scenarios proposed to explain the nature of the outburst, the most promising is a stellar merger event. The results of spectroscopic observations of the object obtained in October 2005 with the Keck/HIRES instrument, presented in detail in Paper I, are analysed and discussed. Our analysis of the molecular bands and the P-Cyg profiles of atomic lines shows that the object loses matter with a velocity of up to 215 km/s and a rate of 10^{-6} - 10^{-5} M_sun/yr. In the profiles of some atomic lines, we have also found evidence of matter infall. A narrow absorption component, which is particularly strong in some P-Cyg profiles, may indicate that a jet-like outflow has also been formed. We show that the observed emission in the [Fe II] lines and an eclipse-like event observed in November/December 2006 was probably caused by interactions of the expanding matter, ejected by V838 Mon in 2002, with radiation from the B3V companion. In particular, the observed profiles of the [Fe II] lines can be easily modelled in this scenario and allow us to estimate parameters of the system, such as the position of the B3V companion relative to V838 Mon and the line of sight, density in the outflowing matter, and mass lost in the 2002 eruption. The observed appearance of strong H-alpha emission, just before and during the eclipse-like event, can be interpreted as a result of the accretion of the outflowing matter onto the B3V companion: the accreted matter, shocked above the stellar surface, can be a source of extreme-UV and soft X-ray radiation capable of ionizing and exciting H in the outflow.

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arXiv2009

Keck/HIRES spectroscopy of V838 Monocerotis in October 2005

V838 Mon erupted at the beginning of 2002 becoming an extremely luminous star. Among various scenarios proposed to explain the nature of the outburst the most promising is a stellar merger event. In this paper we investigate the observational properties of the star and its surroundings in the post outburst phase. We have obtained a high resolution optical spectrum of V838 Mon in October 2005 using the Keck I telescope.We have identified numerous atomic features and molecular bands present in the spectrum and provided an atlas of those features. In order to improve the spectrum interpretation we have performed simple modeling of the molecular bands. Our analysis indicates that the spectrum is dominated by molecular absorption features arising in photospheric regions with temperatures of ~2400 K and in colder outer layers, where the temperature decreases down to ~500 K. A number of resonance lines of neutral alkali metals are observed to show P-Cyg profiles. Particularly interesting are numerous prominent emission lines of [FeII]. All of them show practically the same profile, which can be well described by a Lorentzian profile. In the blue part of the spectrum photospheric signatures of the B-type companion are easily seen. We have fitted the observed spectrum with a synthetic one and the obtained parameters are consistent with the B3V type. We have also estimated radial and rotational velocities of the companion.

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arXiv2007

Observations of V838 Mon in the CO rotational lines

We investigate the structure of a field around the position of V838 Mon as seen in the lowest CO rotational transitions. We also measure and analyse emission in the same lines at the position of V838 Mon.Observations have primarily been done in the CO J = 2-1 and J = 3-2 lines using the KOSMA telescope. A field of 3.4 squared degrees has been mapped in the on-the-fly mode in these transitions. Longer integration spectra in the on-off mode have been obtained to study the emission at the position of V838 Mon. Selected positions in the field have also been observed in the CO J = 1-0 transition using the Delingha telescope.In the observed field we have identified many molecular clouds. They can be divided into two groups from the point of view of their observed radial velocities. One, having V(LSR) in the range 18-32 km/s, can be identified with the Perseus Galactic arm. The other one, having V(LSR) between 44-57 km/s, probably belongs to the Norma-Cygnus arm. The radial velocity of V838 Mon is within the second range but the object does not seem to be related to any of the observed clouds. We did not find any molecular buble of a 1 degree dimension around the position of V838 Mon claimed in van Loon et al. An emission has been detected at the position of the object in the CO J = 2-1 and J = 3-2 transitions. The emission is very narrow (FWHM ~ 1.2 km/s) and at V(LSR) = 53.3 km/s. Our analysis of the data suggests that the emission is probably extended.

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arXiv2006

Observations of V838 Mon and the nearby region in the CO J = 1-0, 2-1 and 3-2 transitions

We present observations of V838 Mon and its close vicinity in the three lowest rotational transitions of CO. The J = 2-1 and 3-2 data were obtained using the 3 m KOSMA telescope. They include on-the-fly maps covering a large area (~3.4 sq. deg.) around V838 Mon and long integrations on the star position. Complementary observations in the CO J = 1-0 transition were obtained using the 13.7 m Delingha telescope. The star position as well as 25 other points preselected in the near vicinity of the object have been measured in this transition. We report on a detection of two narrow emission components in J = 2-1 and 3-2 transitions at the position of V838 Mon. Lines were found at radial velocities of V_lsr=53.3 km/s and V_lsr=-11.0 km/s. Their origin is unclear. We also shortly discuss results of the observations of the vicinity of V838 Mon.

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