Far-infrared Sources Research Articles

CO outflows from young stars in the NGC2023 cluster

Young early-type HAeBe stars are still embedded in the molecular clouds in which they formed. They illuminate reflection nebulae, which shape the surrounding molecular cloud and may trigger star formation. They are therefore ideal places to search for ongoing star formation activity. NGC\,2023 is illuminated by the Herbig Be star HD\,37903. It is the most massive member of a small young cluster with about 30 PMS stars, several of which are Class I objects that still heavily accrete. It might therefore be expected that they might drive molecular outflows. We examined the whole region for outflows. We analyzed previously published APEX data to search for and characterize the outflows in the NGC\,2023 region. This is the first systematic search for molecular outflows in this region. Since the outflows were mapped in several CO transitions, we can determine their properties quite well. We have discovered four molecular outflows in the vicinity of NGC\,2023, three of which are associated with Class I objects. MIR-63, a bright mid-infrared and submillimeter Class I source, is a binary with a separation of 2 and drives two bipolar outflows orthogonal to each other. The large southeast--northwest outflow excites the Herbig-Haro flow HH\,247. MIR-73, a Class I object, which is also a far-infrared source, drives a pole-on outflow. MIR-62 is a Class II object with strong infrared excess and a luminosity of 7 It is not detected in the far-infrared. The Class I sources have bolometric luminosities of about 20 or lower, that is, they are all low-mass stars. One other far-infrared source, MIR-75, may have powered an outflow in the past because it now illuminates an egg-shaped cavity. The four outflows are all powered by young stars and are located in the immediate vicinity of NGC\,2023. They are at a similar evolutionary stage, which suggests that their formation may have been triggered by the expanding region.

Giant and broadband THz and IR emission in drift-biased graphene-based hyperbolic nanostructures

We demonstrate that Cherenkov radiation can be manipulated in terms of operation frequency, bandwidth, and efficiency by simultaneously controlling the properties of drifting electrons and the photonic states supported by their surrounding media. We analytically show that the radiation rate strongly depends on the momentum of the excited photonic state, in terms of magnitude, frequency dispersion, and its variation vs the properties of the drifting carriers. This approach is applied to design and realize miniaturized, broadband, tunable, and efficient terahertz and far-infrared sources by manipulating and boosting the coupling between drifting electrons and engineered hyperbolic modes in graphene-based nanostructures. The broadband, dispersive, and confined nature of hyperbolic modes relax momentum matching issues, avoid using electron beams, and drastically enhance the radiation rate—allowing that over 90% of drifting electrons emit photons. Our findings open an exciting paradigm for the development of solid-state terahertz and infrared sources.

A multiwavelength study of the IRAS 23139+5939 (G111.256−0.770) star-forming site and its relation to Sh2-157

ABSTRACTThe far-infrared source IRAS 23139+5939 (G111.25−0.77) is a well-studied massive star-forming region at the centre of a dense molecular clump. It is associated with a low-luminosity and variable methanol maser, a number of water maser clusters, and several compact H ii regions. We present new sub-arcsec-resolution broad- and narrow-band near- and mid-infrared calibrated images. These were analysed together with Wide-field Infrared Survey Explorer images and longer wavelength published data. We establish that IRAS 23139+5939 is a multiple massive young stellar object (YSO) with a spectral energy distribution characteristic of a Class I object. Its deeply embedded (AV = 21) central YSOs have a total luminosity of 3 × 104 L⊙ and a mass of 16 M⊙. We find several small knots of H2 emission in its vicinity, bordering a large CO outflow driven by the protostar. Their distribution suggests the presence of several YSOs with jets. A young embedded stellar cluster of size ∼40 arcsec (0.65 pc) is found around the massive protostar, with evidence of protoplanetary discs in more than 50 per cent of the likely members. We also report a large arc of H2 emission surrounding a nearby H α-emission star displaying a large infrared excess, with a total luminosity of 1.5 × 103 L⊙. Gaia Data Release 3 and very long baseline interferometry parallaxes indicate a common distance of 3.34 kpc to these two YSOs, a distance similar to that to Sh2-157, a nearby massive star-forming region, which appears connected to IRAS 23139+5939 by a warm dust filament.

The Lockman-SpReSO project

Context. Extragalactic surveys are a key tool for better understanding the evolution of galaxies. Both deep and wide-field surveys serve to provide a clearer emerging picture of the physical processes that take place in and around galaxies, and to identify which of these processes are the most important in shaping the properties of galaxies. Aims. The Lockman Spectroscopic Redshift Survey using Osiris (Lockman-SpReSO) aims to provide one of the most complete optical spectroscopic follow-ups of the far-infrared (FIR) sources detected by the Herschel Space Observatory in the Lockman Hole (LH) field. The optical spectroscopic study of the FIR-selected galaxies supplies valuable information about the relation between fundamental FIR and optical parameters, including extinction, star formation rate, and gas metallicity. In this article, we introduce and provide an in-depth description of the Lockman-SpReSO project and of its early results. Methods. We selected FIR sources from Herschel observations of the central 24 arcmin ×24 arcmin of the LH field with an optical counterpart up to 24.5 RC(AB). The sample comprises 956 Herschel FIR sources, plus 188 additional interesting objects in the field. These are point X-ray sources, cataclysmic variable star candidates, high-velocity halo star candidates, radio sources, very red quasi-stellar objects, and optical counterparts of sub-millimetre galaxies. The faint component of the catalogue (RC(AB) ≥ 20) was observed using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias in multi-object spectroscopy (MOS) mode. The bright component was observed using two multi-fibre spectrographs: the AF2-WYFFOS at the William Herschel Telescope and the HYDRA instrument at the WYIN telescope. Results. From an input catalogue of 1144 sources, we measured a secure spectroscopic redshift in the range 0.03 ≲ z ≲ 4.96 for 357 sources with at least two identified spectral lines. In addition, for 99 sources that show only one emission or absorption line, a spectroscopic redshift was postulated based on the line and object properties, and photometric redshift. In both cases, properties of emission and absorption lines were measured. Furthermore, to characterize the sample in more depth with determined spectroscopic redshifts, spectral energy distribution (SED) fits were performed using the CIGALE software. The IR luminosity and the stellar mass estimations for the sample are also presented as a preliminary description.

The rotational spectrum of HD broadened by H2 at temperatures between 100 – 296 K

Laboratory measurements of the R(0) – R(3) pure rotational transitions of hydrogen deuteride (HD) have been performed at low pressures (< 1 bar) and temperatures between 98 and 296 K. The measurements were conducted using a Fourier transform spectrometer coupled to the Soleil synchrotron far-infrared source to obtain pure HD and HD-H2 mixture spectra. The observed spectra have been fitted using a non-linear least-squares multispectral fitting program. For each transition the line position, intensity, pressure broadening, pressure-induced frequency shift, and the temperature dependencies of these quantities have been determined simultaneously. These spectroscopic line parameters are compared to previous measurements made at higher gas pressures. Notably the present, and previous, measurements of the self- and H2-broadened linewidths are smaller by a factor of five compared with those listed in the HITRAN and GEISA databases. This work is applicable to the low pressure, low temperature regimes found in the atmospheres of the giant gaseous planets.

Inactivation of viruses on surfaces by infrared techniques

Several studies on vaccines and medicines against virus-based illnesses (COVID-19, SARS, MERS) are being conducted worldwide. However, virus mutation is an issue. Therefore, inactivation and disinfection of viruses are crucial. This paper presents a method for virus inactivation by physical techniques. The infrared (IR) technique is preferred over other disinfection techniques such as ultraviolet (UV) and chemical disinfectants (alcohol) due to the associated health and environmental benefits.In this study, IR sources with various wavelengths were characterized and a far infrared (FIR) source was used to inactivate viruses. FIR sources have a therapeutic effect on the human body and have been used in medical centers. Virus spread is highly affected by environmental conditions such as temperature, humidity, and airflow. A setup with IR sources, an IR camera, an automatically controlled humidity chamber, and an airflow unit was constructed to study the viability of viruses in stationary droplets as a function of relative humidity and temperature. Bacteriophage Phi6 was used as a model organism for studying enveloped viruses such as influenza and coronavirus. IR techniques were used for studying virus inactivation. The effect of various physical conditions such as temperature, humidity, and airflows was considered to study the effect of radiation on the stationary droplets of Phi6. All measurements were performed under laboratory conditions with controlled temperature and humidity. The IR camera system was used to measure the surface temperature of Phi6 suspension droplets. The samples subjected to IR radiation were processed for plaque assay preparation and counting. Measurements were carried out to reduce and eliminate droplets, which are one of the transmission pathways of viruses. IR was radiated in closed and open-air conditions with appropriate humidity and temperature.This study reports the effective inactivation of viruses by FIR. The inactivation rate under 50 %rh for IR radiated at 1.4 m height for 3 h in closed environmental chamber was 90%, and that under an airflow rate of 0.20 m/s for 10 min in open-air conditions at a height of 1.0 m was 45.7%.

Star Formation Triggered by the Expanding Bubble S111

Abstract This paper investigates the impact of radiative and mechanical feedback from O-type stars on their parent molecular clouds and the triggering of formation of a future generation of stars. We study the infrared bubble S111 created by the embedded massive stellar cluster G316.80–0.05. A significant fraction of gas in shells created due to the compression of the ambient medium by expanding bubbles is photodissociated by the stellar radiation. The kinematics of the shells are thus best studied using spectroscopic observations of singly ionized carbon, the most dominant species. We have used velocity-resolved maps of the 2P3/2 → 2P1/2 transition of [C ii] at 158 μm, the J = 2–1 transition of 13CO and C18O, and the J = 1–0 transition of HCO+ to study the rim of the bubble S111 that partly coincides with the southern part of the infrared dark ridge G316.75. The [C ii] spectra conclusively show evidence of a shell expanding with a moderate velocity of ∼7 km s−1, which amounts to a kinetic energy that is ∼0.5–40 times the thermal energy of the H ii region. The pressure causing the expansion of the H ii region arises mainly from hydrogen ionization and dust-processed radiation. Among the far-infrared sources located in compressed shells, we find the core G316.7799–0.0942 to show broad spectral features consistent with outflow activity and conclude that it is a site of active star formation. Based on the age of the H ii region we conclude that this expanding H ii region is responsible for triggering the current star formation activity in the region.

Near-infrared detection of H2 flows in the core of the Mon R1 association

ABSTRACT We report the discovery of four new H2 jets in the Mon R1 star-forming region in images obtained with the 2.5-m telescope of the Caucasian Mountain Observatory of Sternberg Astronomical Institute (SAI), Moscow State University (MSU) through a filter centred on the H2 1–0 S(1) emission line. This discovery confirms the nature of these flows, the existence of which was previously suspected from archival Spitzer GLIMPSE360 and Wide-field Infrared Survey Explorer (WISE) survey images. Also, two infrared reflection nebulae were revealed. On Herschel Photodetecting Array Camera and Spectrometer (PACS) survey images, we found a small group of far-infrared sources, mostly unknown ones; among them are the possible exciting objects of these outflows. Spectral energy distributions of the new sources show their extremely red colour and bolometric luminosities reaching 3 L⊙ and even 10 L⊙. They are thought to be pre-main-sequence (PMS) objects in the very early evolutionary stages.

Study of Electron Dynamics Controlling the Threshold Intensity Dependence on the Gas Pressure in FIR Laser-Induced Breakdown of Molecular Oxygen: Effect of Loss Processes

The current study is dedicated to investigating the electron dynamics of the breakdown and plasma generation in molecular oxygen at a pressure extended from 4.6 to 75 kPa. The breakdown is motivated by far-infrared laser source operational at λ = 10.591 µm, (hν ~ 0.12 eV) with pulse width 2τ = 64 ns (FWHM) (Camacho et al. in J Phys D Appl Phys 41(10):105201, 2008). This experiment presumed the presence of a new electron ignition mechanism to produce a specific density of seed electrons in the interaction region as a substitution of the negligible involvement of the photoionization process. The analysis is grounded on adapting the electron cascade model given in our past paper (Evans and Gamal in J Phys D Appl Phys 13(8):1447, 1980). This model well thought out the determination of the threshold intensity as a function of gas pressure taken into account the possible physical processes which may take place in the interaction volume. In doing so, the governing differential equation that defines the variation of the energy of electrons during the laser pulse is solved numerically together with a set of rate equations presenting the change of population of the excited states. The calculated breakdown threshold intensity showed a reasonable agreement with the measured ones, where both indicated weak dependence over the tested pressure range. This behavior is resolved by studying the individual effect of each loss processes involved in the model on the threshold intensity concerning the experimentally assumed density of the initial electrons corresponding to the tested gas pressure range. Besides, to evaluate the precise involvement of the action of the single loss process to the mechanism responsible for plasma production, computations of the temporal variation of the density of electrons are carried out in the presence and absence of the individual loss process.

SOFIA/HAWC+ Traces the Magnetic Fields in NGC 1068

Abstract We report the first detection of galactic spiral structure by means of thermal emission from magnetically aligned dust grains. Our 89 μm polarimetric imaging of NGC 1068 with the High-resolution Airborne Wideband Camera/Polarimeter (HAWC+) on NASAs Stratospheric Observatory for Infrared Astronomy (SOFIA) also sheds light on magnetic field structure in the vicinity of the galaxy's inner-bar and active galactic nucleus (AGN). We find correlations between the 89 μm magnetic field vectors and other tracers of spiral arms, and a symmetric polarization pattern as a function of the azimuthal angle arising from the projection and inclination of the disk field component in the plane of the sky. The observations can be fit with a logarithmic spiral model with pitch angle of and a disk inclination of 48° ± 2°. We infer that the bulk of the interstellar medium from which the polarized dust emission originates is threaded by a magnetic field that closely follows the spiral arms. Inside the central starburst disk (&lt;1.6 kpc), the degree of polarization is found to be lower than for far-infrared sources in the Milky Way, and has minima at the locations of most intense star formation near the outer ends of the inner-bar. Inside the starburst ring, the field direction deviates from the model, becoming more radial along the leading edges of the inner-bar. The polarized flux and dust temperature peak ∼3″–6″ NE of the AGN at the location of a bow shock between the AGN outflow and the surrounding interstellar medium, but the AGN itself is weakly polarized (&lt;1%) at both 53 and 89 μm.

Temporally and Spatially Coherent Emission from Thermal Embedded Eigenstates

Thermal emission manipulation is of key importance in numerous applications, yet a number of challenges have prevented its full technical maturation. Efficient mid- and far-infrared sources are val...

Discovery of a strong ionized-gas outflow in an AKARI-selected ultra-luminous infrared galaxy at $z$ = 0.5

Abstract In order to construct a sample of ultra-luminous infrared galaxies (ULIRGs; with infrared luminosity LIR &amp;gt; 1012 L${_{\odot} }$) at 0.5 &amp;lt; $z$ &amp;lt; 1, we are conducting an optical follow-up program for bright 90 μm far-infrared sources with a faint optical (i &amp;lt; 20 mag) counterpart selected in the AKARI Far-Infrared Surveyor (FIS) Bright Source catalog (Ver.2). AKARI-FIS-V2 J0916248+073034, identified as a ULIRG at $z$ = 0.49 in the spectroscopic follow-up observation, indicates signatures of an extremely strong outflow in its emission line profiles. Its [O iii] 5007 Å emission line shows a full width at half-maximum (FWHM) of 1830 km s−1 and velocity shift of −770 km s−1 relative to the stellar absorption lines. Furthermore, the low-ionization [O ii] 3726 Å 3729 Å doublet also shows a large FWHM of 910 km s−1 and velocity shift of −380 km s−1. After the removal of an unresolved nuclear component, the long-slit spectroscopy 2D image possibly shows that the outflow extends to a radius of 4 kpc. The mass outflow and energy ejection rates are estimated to be 500 M${_{\odot} }$ yr−1 and 4 × 1044 erg s−1, respectively, which imply that the outflow is among the most powerful ones observed in ULIRGs and quasi-stellar objects at 0.3 &amp;lt; $z$ &amp;lt; 1.6. The co-existence of the strong outflow and intense star formation (star formation rate of 990 M${_{\odot} }$ yr−1) indicates that the feedback of the strong outflow has not severely affected the star-forming region of the galaxy.

A zone of avoidance catalogue of 2MASS bright galaxies – I. Sample description and analysis

We present a homogeneous 2MASS bright galaxy catalogue at low Galactic latitudes ($|b| \le 10.0^{\rm o}$, called Zone of Avoidance) which is complete to a Galactic extinction-corrected magnitude of $K^o_s \le 11.25^{\rm m}$. It also includes galaxies in regions of high foreground extinctions ($E(B-V) > 0.95^{\rm m}$) situated at higher latitudes. This catalogue forms the basis of studies of large-scale structures, flow fields and extinction across the ZoA and complements the ongoing 2MASS Redshift and Tully-Fisher surveys. It comprises 3763 galaxies, 70% of which have at least one radial velocity measurement in the literature. The catalogue is complete up to star density levels of $\log N_*/{\rm deg}^2 <4.5$ and at least for $A_K < 0.6^{\rm m}$ and likely as high as $A_K = 20^{\rm m}$. Thus the ZoA in terms of bright NIR galaxies covers only $2.5-4$% of the whole sky. We use a diameter-dependent extinction correction to compare our sample with an unobscured, high-latitude sample. While the correction to the $K_s$ -band magnitude is sufficient, the corrected diameters are too small by about $4''$ on average. The omission of applying such a diameter-dependent extinction correction may lead to a biased flow field even at intermediate extinction values as found in the 2MRS survey. A slight dependence of galaxy colour with stellar density indicates that unsubtracted foreground stars make galaxies appear bluer. Furthermore, far-infrared sources in the DIRBE/IRAS extinction maps that were not removed at low latitudes affect the foreground extinction corrections of three galaxies and may weakly affect a further estimated $\approx 20$% of our galaxies.

Cosmic happenstance: 24-µm selected, multicomponent Herschel sources are line-of-sight projections

In this paper, we investigate the physical associations between blended far-infrared (FIR)-emitting galaxies, in order to identify the level of line-of-sight projection contamination in the single-dish Herschel data. Building on previous work, and as part of the Herschel Extragalactic Legacy Project (HELP), we identify a sample of galaxies in the COSMOS field which are found to be both FIR-bright (typically $\sim 15$ mJy) and blended within the Herschel 250 $\mu$m beam. We identify a spectroscopic or photometric redshift for each FIR-bright source. We conduct a joint probability distribution analysis on the redshift probability density functions to determine the fraction of the FIR sources with multiple FIR-bright counterparts which are likely to be found at consistent ($\Delta z$ $< 0.01$) redshifts. We find that only 3 (0.4 per cent) of the pair permutations between counterparts are $>50$ per cent likely to be at consistent redshifts. A majority of counterparts (72 per cent) have no overlap in their redshift probability distributions whatsoever. This is in good agreement with the results of recent simulations, which indicate that single-dish observations of the FIR sky should be strongly contaminated by line of sight projection effects. We conclude that for our sample of 3.6- and 24-$\mu$m selected, FIR-bright objects in the COSMOS field, the overwhelming majority of multi-component FIR systems are line of sight projections within the 18.1 arcsec Herschel beam, rather than physical associations.

AKARI ALL-SKY BRIGHT SOURCE CATALOGUE: FAR-INFRARED LUMINOUS QUASARS AND THE OPTICAL FAR-INFRARED CORRELATION

We have identified 22 quasars in the AKARI far-infrared all-sky Bright Source Catalogue, using a matching radius of 1 are magnified with respect to the predicted far-infrared luminosity, and consider this may be due to gravitational lensing. If confirmed, this would provide a new way to identify lenses; if not, we may have identified an interesting new population of extreme starbursting quasars.

AKARI DEEP FIELD SOUTH: SPECTROSCOPIC OBSERVATIONS OF INFRARED SOURCES

We present a summary of our spectroscopic redshift catalogue of 404 sources in the AKARI Deep Field South (ADF-S). We have used the AAOmega spectrograph to target mid-infrared and far-infrared sources selected primarily from AKARI observations in this field for which we were able to obtain optical counterparts. Our sources with identified redshifts include 316 with <TEX>$H{\alpha}$</TEX> detections at <TEX>$z{\leq}0.345$</TEX> and 15 sources at z > 1 with MgII or <TEX>$Ly{\alpha}$</TEX> emission lines. About 13% of our <TEX>$z{\leq}0.345$</TEX> sources are dominated by active galactic nuclei (AGN) emission, although many show emission from both star formation and AGNs. The median Balmer decrement is 5.9. Ultra-luminous infrared galaxies (ULIRGs) were found only in the higher-redshift sources. Optical and near infrared data will be available shortly, enabling calibration of the line luminosities and spectral energy distribution (SED) fitting for these sources.

Heat Effects from Far-Infrared Source towards Antioxidant Activity in &lt;i&gt;Aquilaria&lt;/i&gt; &lt;i&gt;subintegra&lt;/i&gt; Leaves

Aquilaria tree is known for its ability of producing high quality resin called agarwood or gaharu oil. The leaves of this tree were under utilized and it is also claimed to be useful for treating a certain diseases. This study was aimed to identify the present of antioxidant activities in Aquilariasubintegra leaves. In the meantime, the effect of drying temperature from far-infrared (FIR) sources on antioxidant activity of the plant leaves was studied. Leaves were dried at different temperatures (40 °C, 50 °C, 60 °C) by using a (FIR) dryer. DPPH method was used to identify the scavenging activity (IC50) of the methanolic leaves extracts. The result showed that methanol extract of the sample dried at 50 °C exhibited the highest antioxidant activity (IC50 of 619.89μg/ml). In the range of temperature studied, 50 °C is proposed to be an appropriate drying temperature when using FIR as the source of heating element. In conclusion, FIR helps in lowering the drying temperature of Aquilariasubintegra leaves that retain significant amount of antioxidant activities which could be beneficial for treating certain diseases as claimed by others.

Source clustering in the Hi-GAL survey determined using a minimum spanning tree method

Aims. The aims are to investigate the clustering of the far-infrared sources from the Herschel infrared Galactic Plane Survey (Hi-GAL) in the Galactic longitude range of −71 to 67 deg. These clumps, and their spatial distribution, are an imprint of the original conditions within a molecular cloud. This will produce a catalogue of over-densities. Methods. The minimum spanning tree (MST) method was used to identify the over-densities in two dimensions. The catalogue was further refined by folding in heliocentric distances, resulting in more reliable over-densities, which are cluster candidates. Results. We found 1633 over-densities with more than ten members. Of these, 496 are defined as cluster candidates because of the reliability of the distances, with a further 1137 potential cluster candidates. The spatial distributions of the cluster candidates are different in the first and fourth quadrants, with all clusters following the spiral structure of the Milky Way. The cluster candidates are fractal. The clump mass functions of the clustered and isolated are statistically indistinguishable from each other and are consistent with Kroupa’s initial mass function.

Total infrared luminosity estimation from local galaxies in AKARI all sky survey

We aim to use the a new and improved version of AKARI all sky survey catalogue of far-infrared sources to recalibrate the formula to derive the total infrared luminosity. We cross-match the faint source catalogue (FSC) of IRAS with the new AKARI-FIS and obtained a sample of 2430 objects. Then we calculate the total infrared (TIR) luminosity $L_{\textrm{TIR}}$ from the Sanders at al. (1996) formula and compare it with total infrared luminosity from AKARI FIS bands to obtain new coefficients for the general relation to convert FIR luminosity from AKARI bands to the TIR luminosity.

WATER MASERS IN THE ANDROMEDA GALAXY. II. WHERE DO MASERS ARISE?

ABSTRACT We present a comparative multiwavelength analysis of water-maser-emitting regions and non-maser-emitting luminous 24 μm star-forming regions in the Andromeda Galaxy (M31) to identify the sites most likely to produce luminous water masers useful for astrometry and proper motion studies. Included in the analysis are Spitzer 24 μm photometry, Herschel 70 and 160 μm photometry, Hα emission, dust temperature, and star-formation rate. We find significant differences between the maser-emitting and non-maser-emitting regions: water-maser-emitting regions tend to be more infrared-luminous and show higher star-formation rates. The five water masers in M31 are consistent with being analogs of water masers in Galactic star-forming regions and represent the high-luminosity tail of a larger (and as yet undetected) population. Most regions likely to produce water masers bright enough for proper motion measurements using current facilities have already been surveyed, but we suggest three ways to detect additional water masers in M31: (1) reobserve the most luminous mid- or far-infrared sources with higher sensitivity than was used in the Green Bank Telescope survey; (2) observe early-stage star-forming regions selected by millimeter continuum that have not already been selected by their 24 μm emission, and (3) reobserve the most luminous mid- or far-infrared sources and rely on maser variability for new detections.