A Comprehensive Study of the Young Cluster IRAS 05100+3723: Properties, Surrounding Interstellar Matter, and Associated Star Formation (original) (raw)

Iras 20050+2720: Anatomy of a Young Stellar Cluster

The Astronomical Journal, 2012

IRAS 20050+2720 is young star-forming region at a distance of 700 pc without apparent high-mass stars. We present results of our multi-wavelength study of IRAS 20050+2720 which includes observations by Chandra and Spitzer, and Two Micron All Sky Survey and UBVRI photometry. In total, about 300 young stellar objects (YSOs) in different evolutionary stages are found. We characterize the distribution of YSOs in this region using a minimum spanning tree analysis. We newly identify a second cluster core, which consists mostly of class II objects, about 10 from the center of the cloud. YSOs of earlier evolutionary stages are more clustered than more evolved objects. The X-ray luminosity function (XLF) of IRAS 20050+2720 is roughly lognormal, but steeper than the XLF of the more massive Orion Nebula complex. IRAS 20050+2720 shows a lower N H /A K ratio compared with the diffuse interstellar medium.

The young stellar cluster associated with IRAS 09149-4743

Astronomy and Astrophysics, 2007

Context. We present the results of a near-infrared survey of the young stellar cluster associated with IRAS 09149-4743, a member of the Vela Molecular Ridge. Aims. The main purpose of this survey is to study the cluster members and find the ionizing sources of the associated HII region. Methods. Infrared photometry of 62 stars located in the crowded parts of the cluster is given in the J, H, and K bands. Colour-colour and colour-magnitude diagrams are drawn to obtain an estimate of their spectral type and reddening. Results. Three main sources are identified as candidates to ionize the HII region: a star located at the centre of the cluster, inside the IRAS error ellipse; a second star, member of a small "subcluster" situated 1.1 to the southeast of the former; and a third object, showing very high colour indices, which indicate visual extinction over 20 mag. Dereddened J magnitudes suggest that the former two stars probably are the main ionizing sources, whereas the latter is too reddened to allow a reliable estimate of its spectral type by photometric methods.

Discovery of a Young Massive Stellar Cluster Associated with IRAS Source 16177-5018

The Astronomical Journal, 2003

We report the discovery of a young massive stellar cluster embedded in an extended HII region, invisible at optical wavelengths where the extinction is A V ≈ 28 magnitudes, associated with the IRAS source 16177-5018. J, H and nbK imaging photometry combined with the K S 2MASS data show the presence of sources with infrared excess emission at 2.2 µm, concentrated in an area of about one square parsec around a massive young stellar object identified as the IRAS source. This object has a near-mid infrared spectral index betweem 2.2 and 25 µm α(IR) = d log(λF λ)/d logλ =4.78, characteristic of compact H II regions, with bolometric luminosity, inferred from the integrated near to far-infrared flux density of 2.8 × 10 5 L ⊙ , which corresponds to a ZAMS star of about 42M ⊙. From the color-magnitude diagram we were able to classify the majority of the cluster members as reddened massive stars earlier than spectral type B5.

Not a galaxy: IRAS 04186+5143, a new young stellar cluster in the outer Galaxy

Monthly Notices of the Royal Astronomical Society, 2015

We report the discovery of a new young stellar cluster in the outer Galaxy located at the position of an IRAS PSC source that has been previously mis-identified as an external galaxy. The cluster is seen in our near-infrared imaging towards IRAS 04186+5143 and in archive Spitzer images confirming the young stellar nature of the sources detected. There is also evidence of sub-clustering seen in the spatial distributions of young stars and of gas and dust. Near-and mid-infrared photometry indicates that the stars exhibit colours compatible with reddening by interstellar and circumstellar dust and are likely to be lowand intermediate-mass YSOs with a large proportion of Class I YSOs. Ammonia and CO lines were detected, with the CO emission well centred near the position of the richest part of the cluster. The velocity of the CO and NH 3 lines indicates that the gas is Galactic and located at a distance of about 5.5 kpc, in the outer Galaxy. Herschel data of this region characterise the dust environment of this molecular cloud core where the young cluster is embedded. We derive masses, luminosities and temperatures of the molecular clumps where the young stars reside and discuss their evolutionary stages.

The Multiple Systems in The Young Stellar Cluster located in the vicinity of IRAS 05137+3919 source

Four binary objects and one triplet have been revealed in the young stellar cluster located in the vicinity of IRAS 05137+3919 source on a distance 4.4 kpc with the use of statistic analysis (2PCF, Poisson statistic). They are including the pair of AeBe stars. The percentage of the multiple systems in the cluster is mf = 5 and cp = 10.It should be noticed, that the use of the different databases, namely 2MASS and GPS UKIDSS, which are differ by both photometric limit and resolution, do not affect the value of these parameters. The mass of the multiple systems' components are located in the range from 1 to 8 Msol and log P (rotation period in years) - from 4.4 to 4.7. The median value of the mass ratio of the components is q = 0.73. The percentage of the multiple systems and their parameters in this cluster is resembling with the data obtained in the other star forming regions (ONC, Perseus, U Sco A), in which the value of mf and cp parameters are comparable with the results obta...

The sequence of low- and high-mass star formation in the young stellar cluster IRAS 19343+2026

Monthly Notices of the Royal Astronomical Society, 2010

BV RIJHK photometry, Spitzer-GLIMPSE photometry and HK band spectroscopy were used to study the stellar content of IRAS 19343+2026, a (proto)star/cluster candidate, located close to the Galactic plane. The data suggest that IRAS 19343+2026 is a rich cluster associated with a massive protostar of 7.6 M ⊙ with an age of ∼ 10 5 yr. Three point sources in the vicinity of the far-infrared (FIR) peak are also found to be early B type stars. The remaining (predominantly low mass) members of the cluster are best represented by a 1 -3 Myr pre-main-sequence (PMS) population. HK band spectra of two bright and five faint point sources in the cluster confirm that the results obtained from the photometry are good representations of their young stellar object (YSO) nature. Thus, IRAS 19343+2026 is a young cluster with at least four early B-type stars classified as young (10 4 -10 5 yr), that are surrounded by a somewhat older (1 -3 Myr) population of low mass YSOs. Together, these results argue for a scenario in which low mass stars form prior to massive stars in a cluster forming environment. We compute the Initial Mass Function (IMF) for this cluster using the K-band luminosity function; the slope of the IMF is shallower than predicted by the Salpeter's mass function. The cluster mass, M total , is estimated to be in the range ∼ 307 M ⊙ (from the data completeness limit) -585 M ⊙ (extrapolated down to the brown dwarf limit, assuming a certain IMF). stellar object in the Galactic mid-plane, we attempt to examine such discrepancies, measure the stellar content, and understand the sequence of low and high mass star formation in the associated cluster. The high quality NIR photometric and spectroscopic data are combined with Spitzer IRAC and MIPS observations to study the target. Study of the massive star content is particularly aided by radiative transfer modelling of the SED. The target, ⋆

The Stellar Population Associated with the IRAS Source 16132-5039

The Astronomical Journal, 2004

We report the discovery of a young massive stellar cluster and infrared nebula in the direction of the CS molecular cloud associated to the IRAS point source 16132-5039. The analysis of the mid-infrared images from the more accurate MSX catalog, reveled that there are two independent components associated with the IRAS source. The integral of the spectral energy distribution for these components, between 8.28 µm and 100 µm, gave lower limits for the bolometric luminosity of the embedded objects of 8.7 × 10 4 L ⊙ and 9 × 10 3 L ⊙ , which corresponds to ZAMS O8 and B0.5 stars, respectively. The number of Lyman continuum photons expected from the stars that lie along the reddening line for early-type stars is about 1.7 × 10 49 s −1 , enough to produce the detected flux densities at 5 GHz. The NIR spectrum of the nebula increases with frequency, implying that free-free emission cannot be the main source of the extended luminosity, from which we conclude that the observed emission must be mainly dust scattered light. A comparison of the cluster described in this paper with the young stellar cluster associated with the IRAS source 16177-5018, which is located at the same distance and direction, shows that the mean visual absorption of the newly discovered cluster is about 10 magnitudes smaller and it contains less massive stars, suggesting that it was formed from a less massive molecular cloud.

IRAS 18317−0757: A Cluster of Embedded Massive Stars and Protostars

The Astrophysical Journal, 2004

We present high resolution, multiwavelength continuum and molecular line images of the massive star-forming region IRAS 18317−0757. The global infrared through millimeter spectral energy distribution can be approximated by a two temperature model (25K and 63K) with a total luminosity of approximately log(L/L ⊙ ) = 5.2. Previous submillimeter imaging resolved this region into a cluster of five dust cores, one of which is associated with the ultracompact H II region G23.955+0.150, and another with a water maser. In our new 2.7mm continuum image obtained with BIMA, only the UCH II region is detected, with total flux and morphology in good agreement with the free-free emission in the VLA centimeterwave maps. For the other four objects, the non-detections at 2.7mm and in the MSX mid-infrared bands are consistent with cool dust emission with a temperature of 13-40K and a luminosity of 1000-40000 L ⊙ . By combining single-dish and interferometric data, we have identified over two dozen virialized C 18 O cores in this region which contain ≈ 40% of the total molecular gas mass present. While the overall extent of the C 18 O and dust emission is similar, their emission peaks do not correlate well in detail. At least 11 of the 123 infrared stars identified by 2MASS in this region are likely to be associated with the star-forming cluster. Two of these objects (both associated with UCH II) were previously identified as O stars via infrared spectroscopy. Most of the rest of the reddened stars have no obvious correlation with the C 18 O cores or the dust continuum sources. In summary, our observations indicate that considerable fragmentation of the molecular cloud has taken place during the time required for the UCH II region to form and for the O stars to become detectable at infrared wavelengths. Additional star formation appears to be ongoing on the periphery of the central region where up to four B-type (proto)stars have formed amongst a substantial number of C 18 O cores.

Radio and IR study of the massive star-forming region IRAS 16353−4636

Astronomy & Astrophysics, 2010

Context. With the latest infrared surveys, the number of massive protostellar candidates has increased significantly. New studies have posed additional questions on important issues about the formation, evolution, and other phenomena related to them. Complementary to infrared data, radio observations are a good tool to study the nature of these objects, and to diagnose the formation stage. Aims. Here we study the far-infrared source IRAS 16353-4636 with the aim of understanding its nature and origin. In particular, we search for young stellar objects (YSOs), possible outflow structure, and the presence of non-thermal emission. Methods. Using high-resolution, multi-wavelength radio continuum data obtained with the Australia Telescope Compact Array ⋆ , we image IRAS 16353-4636 and its environment from 1.4 to 19.6 GHz, and derive the distribution of the spectral index at maximum angular resolution. We also present new JHK s photometry and spectroscopy data obtained at ESO NTT ⋆⋆ . 13 CO and archival H i line data, and infrared databases (MSX, GLIMPSE, MIPSGal) are also inspected. Results. The radio continuum emission associated with IRAS 16353-4636 was found to be extended (∼10 arcsec), with a bow-shaped morphology above 4.8 GHz, and a strong peak persistent at all frequencies. The NIR photometry led us to identify ten near-IR sources and classify them according to their color. We used the H i line data to derive the source distance, and analyzed the kinematical information from the CO and NIR lines detected. Conclusions. We have identified the source IRAS 16353−4636 as a new protostellar cluster. In this cluster we recognized three distinct sources: a low-mass YSO, a high-mass YSOs, and a mildly confined region of intense and non-thermal radio emission. We propose the latter corresponds to the terminal part of an outflow.