An infrared-submillimeter study of starforming regions 
selected by the ISOSS 170 <i>μ</i>m survey

Hennemann, M.; Birkmann, Stephan M.; Krause, O.; Lemke, D.

doi:10.1051/0004-6361:200809384

Cited by 9 publications

(31 citation statements)

References 36 publications

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“…SMM2 hosts a deeply embedded protostellar object that may evolve to a massive YSO. Hennemann et al (2008) find three submillimeter clumps (SMM1-3) in this region, located along a chain from North-East to South-West. SMM2 and SMM3 are associated with bright 24 and 70 μm sources and have masses of 40 and 60 M , whereas SMM1 (100 M ) is not detected with Spitzer.…”

Section: Isossj18364-0221mentioning

confidence: 82%

“…ISOSSJ20153+3453: A single core with a gas mass of ∼120 M and a dust temperature of 17 K was identified in this region by Hennemann et al (2008). Two neighboring mid-infrared sources are detected towards SMM1, the one towards the submillimeter peak is interpreted as embedded YSO that is actively accreting as suggested by the presence of "fuzzy" emission prominent at 4.5 μm.…”

Section: Isossj19486+2556mentioning

confidence: 93%

“…ISOSSJ19357+1950: SCUBA observations (Hennemann et al 2008) reveal three resolved clumps at 450 μm: SMM1 North (0.37 pc, 70 M ) and South (0.31 pc, 50 M ), and SMM2 in the South-West (0.39 pc, 120 M ). SMM2 hosts a deeply embedded protostellar object that may evolve to a massive YSO.…”

Section: Isossj18364-0221mentioning

confidence: 98%

“…Towards SMM1 East, a Class II-like YSO of intermediate central mass has been identified among several 24 μm sources (Hennemann et al 2008). Birkmann et al (2007) identified two cores in this region with ∼200 M each (at 19.5 K and 17.3 K).…”

Section: Isossj20298+3559mentioning

confidence: 99%

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The Earliest Phases of Star Formation (EPoS): aHerschelkey program

Ragan

Henning

Krause

et al. 2012

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Context. Stars are born deeply embedded in molecular clouds. In the earliest embedded phases, protostars emit the bulk of their radiation in the far-infrared wavelength range, where Herschel is perfectly suited to probe at high angular resolution and dynamic range. In the high-mass regime, the birthplaces of protostars are thought to be in the high-density structures known as infrareddark clouds (IRDCs). While massive IRDCs are believed to have the right conditions to give rise to massive stars and clusters, the evolutionary sequence of this process is not well-characterized. Aims. As part of the Earliest Phases of Star formation (EPoS) Herschel guaranteed time key program, we isolate the embedded structures within IRDCs and other cold, massive molecular clouds. We present the full sample of 45 high-mass regions which were mapped at PACS 70, 100, and 160 μm and SPIRE 250, 350, and 500 μm. In the present paper, we characterize a population of cores which appear in the PACS bands and place them into context with their host molecular cloud and investigate their evolutionary stage. Methods. We construct spectral energy distributions (SEDs) of 496 cores which appear in all PACS bands, 34% of which lack counterparts at 24 μm. From single-temperature modified blackbody fits of the SEDs, we derive the temperature, luminosity, and mass of each core. These properties predominantly reflect the conditions in the cold, outer regions. Taking into account optical depth effects and performing simple radiative transfer models, we explore the origin of emission at PACS wavelengths. Results. The core population has a median temperature of 20 K and has masses and luminosities that span four to five orders of magnitude. Cores with a counterpart at 24 μm are warmer and bluer on average than cores without a 24 μm counterpart. We conclude that cores bright at 24 μm are on average more advanced in their evolution, where a central protostar(s) have heated the outer bulk of the core, than 24 μm-dark cores. The 24 μm emission itself can arise in instances where our line of sight aligns with an exposed part of the warm inner core. About 10% of the total cloud mass is found in a given cloud's core population. We uncover over 300 further candidate cores which are dark until 100 μm. These are possibly starless objects, and further observations will help us determine the nature of these very cold cores.

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Section: Isossj18364-0221mentioning

confidence: 82%

Section: Isossj19486+2556mentioning

confidence: 93%

Section: Isossj18364-0221mentioning

confidence: 98%

Section: Isossj20298+3559mentioning

confidence: 99%

See 2 more Smart Citations

The Earliest Phases of Star Formation (EPoS): aHerschelkey program

Ragan

Henning

Krause

et al. 2012

A&A

Self Cite

126

201

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“…They were discovered as dark silhouettes against the galactic background at 8 and 15 µm with the Midcourse Space Experiment (MSX, Egan et al 1998) and ISO (Perault et al 1996). ISO, MSX, the Spitzer Space telescope, and further (sub-)millimeter observations have helped for studying these objects in detail (e.g., Simon et al 2006;Hennemann et al 2008;Vasyunina et al 2009;Ragan et al 2009;Peretto & Fuller 2009). Because IRDCs can only be seen in absorption against a strong infrared background, their location is mainly within the disk toward the inner quadrants of our Milky Way, whereas ISOSS sources are more widely distributed.…”

Section: Introductionmentioning

confidence: 99%

Kinematic and thermal structure at the onset of high-mass star formation

Bihr

Beuther

Linz

et al. 2015

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Context. Even though high-mass stars are crucial for understanding a diversity of processes within our galaxy and beyond, their formation and initial conditions are still poorly constrained. Aims. We want to understand the kinematic and thermal properties of young massive gas clumps prior to and at the earliest evolutionary stages of high-mass star formation. Do we find signatures of gravitational collapse? Do we find temperature gradients in the vicinity or absence of infrared emission sources? Do we find coherent velocity structures toward the center of the dense and cold gas clumps? Methods. To determine kinematics and gas temperatures, we used ammonia, because it is known to be a good tracer and thermometer of dense gas. We observed the NH 3 (1, 1) and (2, 2) lines within six very young high-mass star-forming regions comprised of infrared dark clouds (IRDCs), along with ISO-selected far-infrared emission sources (ISOSS) with the Karl G. Jansky Very Large Array (VLA) and the Effelsberg 100 m Telescope.Results. The molecular line data allows us to study velocity structures, linewidths, and gas temperatures at high spatial resolution of 3−5 , corresponding to ∼0.05 pc at a typical source distance of 2.5 kpc. We find on average cold gas clumps with temperatures in the range between 10 K and 30 K. The observations do not reveal a clear correlation between infrared emission peaks and ammonia temperature peaks. Several infrared emission sources show ammonia temperature peaks up to 30 K, whereas other infrared emission sources show no enhanced kinetic gas temperature in their surrounding. We report an upper limit for the linewidth of ∼1.3 km s −1 , at the spectral resolution limit of our VLA observation. This indicates a relatively low level of turbulence on the scale of the observations. Velocity gradients are present in almost all regions with typical velocity differences of 1 to 2 km s −1 and gradients of 5 to 10 km s −1 pc −1 . These velocity gradients are smooth in most cases, but there is one exceptional source (ISOSS23053), for which we find several velocity components with a steep velocity gradient toward the clump centers that is larger than 30 km s −1 pc −1 . This steep velocity gradient is consistent with recent models of cloud collapse. Furthermore, we report a spatial correlation of ammonia and cold dust, but we also find decreasing ammonia emission close to infrared emission sources.

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Kinematic structure of massive star-forming regions

Tackenberg

Beuther

Henning

et al. 2014

A&A

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Context. The mid-and far-infrared view on high-mass star formation, in particular with the results from the Herschel space observatory, has shed light on many aspects of massive star formation. However, these continuum studies lack kinematic information. Aims. We study the kinematics of the molecular gas in high-mass star-forming regions. Methods. We complemented the PACS and SPIRE far-infrared data of 16 high-mass star-forming regions from the Herschel key project EPoS with N 2 H + molecular line data from the MOPRA and Nobeyama 45 m telescope. Using the full N 2 H + hyperfine structure, we produced column density, velocity, and linewidth maps. These were correlated with PACS 70 μm images and PACS point sources. In addition, we searched for velocity gradients. Results. For several regions, the data suggest that the linewidth on the scale of clumps is dominated by outflows or unresolved velocity gradients. IRDC 18454 and G11.11 show two velocity components along several lines of sight. We find that all regions with a diameter larger than 1 pc show either velocity gradients or fragment into independent structures with distinct velocities. The velocity profiles of three regions with a smooth gradient are consistent with gas flows along the filament, suggesting accretion flows onto the densest regions. Conclusions. We show that the kinematics of several regions have a significant and complex velocity structure. For three filaments, we suggest that gas flows toward the more massive clumps are present.

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An infrared-submillimeter study of starforming regions selected by the ISOSS 170 μm survey

Cited by 9 publications

References 36 publications

The Earliest Phases of Star Formation (EPoS): aHerschelkey program

The Earliest Phases of Star Formation (EPoS): aHerschelkey program

Kinematic and thermal structure at the onset of high-mass star formation

Kinematic structure of massive star-forming regions

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