The Structure and Evolution of Young Stellar Clusters

E. Young; F. C. Adams; J. L. Pipher; J. Muzerolle; L. Allen; P. C. Myers; R. Gutermuth; S. T. Megeath; S. Wolk

REVIEW

The Structure and Evolution of Young Stellar Clusters

L. Allen, S. T. Megeath, R. Gutermuth, P. C. Myers, S. Wolk, F. C. Adams, J. Muzerolle, E. Young

show 1 more author

J. L. Pipher

Astrophysics · Submitted 3 Mar 2006 · 8 references

Pith's verdict: Solid Spitzer-era synthesis; the N-R correlation is real but may be partly baked into the cluster-definition thresholds, and the paper knows it.

T0 · AI review

How this review was made: An AI referee (deepseek-v4-flash) read the paper on August 28, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

T0 AI review An AI read the paper and answered a fixed list of questions.
T1 Audit Automatic checks that the references and files the paper relies on exist and match.
T2 Compute The paper's code or calculations re-run with the same results.
T3 Formal statement The claims written out in a formal math language a computer can read.
T4 Proof Those claims proved, and the proof checked by computer.

How Pith checks papers →

· 2 major objections · 5 minor · Ask about this paper · The compiled record · Read the full review →

Challenge this review Comment (0) Read on arXiv ↗

Cite ▾

arXiv IDastro-ph/0603096 (version 1)

Pith IDJVCWWSVG, Pith's permanent record of this paper and its review

CitationE. Young, F. C. Adams, J. L. Pipher, J. Muzerolle, L. Allen, P. C. Myers, R. Gutermuth, S. T. Megeath, S. Wolk. "The Structure and Evolution of Young Stellar Clusters." arXiv:astro-ph/0603096 (2006). https://pith.science/paper/JVCWWSVG

Cite this reviewBibTeX for Pith's review of this paper

Claim paper

Why Pith says this

Highlight any text to comment on it.

Editor's note

read the letter

Here's the short version. This is a well-written proceedings-style synthesis of new Spitzer and 2MASS surveys of embedded clusters. The genuinely new items are the whole-cloud distributed-population fractions (20-25% of YSOs in between clusters) and the confirmation of the Adams et al. N-R correlation using Spitzer-defined clusters. The paper also gives a useful qualitative catalog of cluster morphologies — elongation, halos, sub-clustering — and shows that protostar positions track dense gas. Those are solid contributions.

The main result, the near-constant surface density (N/R^2 varies by <1 dex while N and R vary by ~2 dex each), is plausible but not fully secure. Both the 2MASS (Carpenter) and Spitzer (Megeath) cluster catalogs define clusters by surface-density thresholds, so the measured N and R are not independent of the definition. The paper says as much in Sec. 3.3, but it does not test how much of the correlation survives different thresholds. The agreement between the two methods is reassuring, but both methods impose the same kind of minimum density, so the agreement does not break the degeneracy. I'd like to see a robustness test or a selection-bias correction before calling this a physical law linking cluster birth to Larson's column-density relation.

The data quality is fine for what it is, and the citation pattern is appropriate for a review, although the heavy reliance on 'in prep' papers (Megeath et al., Allen et al., Gutermuth et al.) for the central numbers makes the results hard to verify in the meantime. That is a genuine weakness, but a curable one — as soon as those catalogs appear, the claims can be checked.

Bottom line: this deserves a serious referee. It makes an important empirical claim, it is honest about its main caveat, and the selection-effect concern is clearly identified even if not resolved. I would not cite it as the last word on the constant-column-density relation, but it is a useful synthesis for anyone working on cluster formation. For a reading group, it's a good example of how cluster definitions shape the conclusions.

Referee report

Significance

If the near-constant surface-density relation is physical, it implies a characteristic stellar column density for embedded clusters and provides a possible observational counterpart to Larson's column-density law for molecular clouds, making the result a useful constraint on cluster formation theories. The paper's qualitative conclusions about morphology and protostar-gas alignment rest on new Spitzer data and are well illustrated. The authors are also commendably explicit about many selection effects: incompleteness, background contamination, and the boundary-dependence of cluster definitions. However, the headline quantitative claim, namely the factor-of-few range in surface density, is not yet demonstrated to be independent of the cluster-finding thresholds, which is the main weakness of the paper.

Major objections (2)

[Section 3.1 and Section 3.3] The central correlation between Nstar and Rcluster may be partly an artifact of the cluster definitions. The 2MASS analysis (Carpenter 2000) defines clusters as closed 2-sigma contours around density peaks exceeding 6 sigma of the background noise, and the Spitzer analysis (Megeath et al. 2006) defines clusters as groups of 10 or more IR-excess sources with a 0.32 pc linking length, explicitly corresponding to about 10 stars pc^-2. Both procedures set a minimum surface density for a group to be called a cluster. For a fixed threshold Sigma_th, any detected cluster satisfies R >= sqrt(N/(pi Sigma_th)), which produces a lower envelope N proportional to R^2 (constant surface density) regardless of the underlying physical distribution. The paper acknowledges in Section 3.3 that the AV = 1 lower envelope 'may result in part from the methods used to identify clusters,' but the abstract and conclusions present the surface-density range as a physical result. To support the claim, the authors should (i) state precisely how Rcluster is measured for each sample (effective radius of the threshold contour, rms radius of members, or maximum projected separation), and (ii) perform a sensitivity test in which the Spitzer cluster sample is re-derived with a range of linking lengths, or the 2MASS contour threshold is varied, and show that the N-R relation and the factor-of-few surface-density range persist. Without such a test, the reader cannot distinguish a physical characteristic column density from a selection effect.
[Section 3.3, abstract, and Conclusion 1] The quantitative description of the surface-density variation is internally inconsistent. The abstract says the average surface density 'varies by a factor of only a few'; Section 3.3 says it 'varies by less than one order of magnitude'; Conclusion 1 says 'a factor of only ~5'. These statements are not equivalent, and the stated bracket AV = 1 to AV = 10 in Fig. 6 corresponds to a factor of 10, i.e., one order of magnitude, not 'a few'. The authors should harmonize these numbers and report the actual range (and scatter) of Nstar/pi R^2 for the plotted data, with uncertainties. In particular, if the bracket is exactly an order of magnitude, the abstract's 'factor of only a few' is an overstatement that should be corrected.

Minor objections (5)

[Section 3.3] The conversion of stellar surface density to AV assumes an average stellar mass of 0.5 solar masses and ignores the substantial gas mass in embedded clusters. Since Larson's column-density law concerns molecular gas, the AV lines in Fig. 6 should be described as a heuristic mapping of stellar surface density to an equivalent gas column, not as a direct measurement of the gas column density. A one-sentence clarification would prevent overinterpretation.
[Section 3.2] The phrase 'the fraction of distributed stars is 32-11%, 26-24%, and 25-21% for the Ophiuchus, Orion A and Orion B clouds respectively' should be written as 11-32%, 24-26%, and 21-25% (or reordered) to avoid the appearance that the higher value is the lower bound.
[Section 3.2] Because the ONC contains 50% (2MASS) to 76% (Spitzer) of the stars in the Nstar >= 100 bin, the derived fraction of stars in large clusters is highly sensitive to the adopted ONC boundary. Please add a quantitative estimate of the uncertainty in this fraction arising from boundary choices, or state explicitly that the value is only approximate.
[Sections 4 and 5] There are small typographical errors: 'concentation' in Section 5 should be 'concentration', and the citation 'Casussus et al. 2000' in Section 4 should be 'Casassus et al. 2000' to match the reference list.
[Section 3.3] The sentence 'This relationship shows that while Nstar varies over 2 orders of magnitude and the cluster radius (Rcluster) varies by almost 2 orders of magnitude' would be clearer if the actual ranges of Nstar and Rcluster plotted in Fig. 6 were stated in the text, along with the number of clusters in each sample.

How Pith checks papers → · Full audit of this paper →

The paper

The paper claims

Nearby embedded clusters show a tight correlation between membership and radius, so their average surface density stays within a factor of about five.

The reading

This paper uses Spitzer and 2MASS censuses of entire nearby molecular clouds to establish what embedded star clusters look like in the nearest kiloparsec. Its central claim is that the number of members in a cluster and its radius are correlated, so the average surface density $N_{\rm star}/\pi R_{\rm cluster}^2$ stays within a factor of about five even as membership ranges from a few to a thousand stars. That near-constant surface density corresponds to a column density between roughly $A_V \sim 1$ and $10$, the same regime as Larson's law for molecular clouds, suggesting cluster birth is tied to gas column density. The paper also shows clusters are commonly elongated, clumpy, and surrounded by low-density halos, and that the youngest protostars trace the filamentary gas, implying these shapes come from the natal cloud rather than later dynamics.

What carries the argument

The machinery is a uniform census of young stellar objects across complete clouds: Spitzer IRAC and MIPS infrared-excess classification to pick out disk-bearing and envelope-bearing members, plus 2MASS star-count maps with a $6\sigma$ peak threshold and $2\sigma$ closed contours for the ground-based sample. Clusters are then defined by explicit rules, groups of 10 or more IR-excess sources linked within 0.32 pc for the Spitzer sample and closed $2\sigma$ contours around peaks exceeding $6\sigma$ above background for the 2MASS sample, and plotted in an $N_{\rm star}$ versus $R_{\rm cluster}$ diagram with lines of constant $A_V$. This diagram is what carries the central claim: it turns two separately measured quantities into a surface density whose narrow range is read as a physical column-density scale for cluster birth.

Extended reading notes

Core claim

On the paper's own terms, the discovery is that embedded clusters form a continuum of environments, not a class of isolated objects, and that their sizes and populations obey a tight relation: $N_{\rm star}$ spans two orders of magnitude and $R_{\rm cluster}$ nearly two, yet $N_{\rm star}/\pi R_{\rm cluster}^2$ varies by less than an order of magnitude, bracketed by lines of constant $A_V = 1$ and $A_V = 10$. The same pattern appears in samples identified by 2MASS star counts and by Spitzer infrared-excess sources, so it is not tied to one cluster-finding method. The paper further claims that the spatial structure of clusters, including elongation, sub-clustering, and halos, mirrors the structure of the parental molecular cloud, most clearly for Class I/0 protostars, and that within 1 kpc fewer than half of young stars sit in strong FUV and EUV fields, with dynamical encounters too rare to truncate disks on solar-system scales.

Load-bearing premise

The whole surface-density correlation rests on how a cluster is defined: change the minimum membership, the linking radius, or the contour thresholds, and both the measured radii and the membership counts change, which the paper itself notes may shape the lower envelope of the relation.

Editorial extensions

If this is right

If the $N_{\rm star}$ versus $R_{\rm cluster}$ relation holds, embedded clusters are born with a characteristic column density near $A_V \sim 1$ to $10$, and cluster birth can be connected directly to Larson's column-density law for molecular clouds.
Because protostar distributions trace filamentary and clumpy gas, cluster elongation and sub-clustering are initial conditions imposed by the natal cloud, so models of cluster formation must reproduce the cloud's fragmentation rather than only later dynamical evolution.
Since fewer than half of nearby young stars are in strong FUV and EUV fields, photoevaporation by massive stars is an environment-dependent disk destruction mechanism, not a universal one.
With cluster densities and lifetimes implying rare close encounters within 100 AU, dynamical encounters should not be the dominant channel for truncating protoplanetary disks on solar-system scales.
Typical gas dispersal times, star formation durations, and crossing times are all about $1$ to $3$ Myr, so embedded clusters are unlikely to reach virial equilibrium before their gas is removed.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

Beyond the paper: the near-constant surface density implies that richer clusters, such as the young super star clusters seen elsewhere in the Galaxy, may grow by increasing radius rather than by strongly increasing central density; that is testable once such clusters are surveyed at comparable completeness.
Beyond the paper: the observed protostar spacing of roughly $0.1$ pc matching the local Jeans length points to a fragmentation scale, which the paper notes but does not itself establish; a direct comparison of protostar nearest-neighbor spacings with Jeans-length maps in more clouds would test it.
Beyond the paper: if cluster definition thresholds partly set the lower envelope of the relation, then the constant surface density may be partly a selection effect; a simulation-based study of how the $N_{\rm star}$ versus $R_{\rm cluster}$ relation responds to selection would separate the physical signal from the method.
Beyond the paper: the finding that morphologies are primordial rather than dynamical suggests that the eventual dissolution of these clusters should be modeled from realistic, elongated, and sub-clustered initial conditions instead of smooth spherical clusters.

Original abstract

We examine the properties of embedded clusters within 1 kiloparsec using new data from the Spitzer Space Telescope, as well as recent results from 2MASS and other ground-based near-infrared surveys. We use surveys of entire molecular clouds to understand the range and distribution of cluster membership, size and surface density. The Spitzer data demonstrate clearly that there is a continuum of star- forming environments, from relative isolation to dense clusters. The number of members of a cluster is correlated with the cluster radius, such that the average surface density of clusters having a few to a thousand members varies by a factor of only a few. The spatial distributions of Spitzer-identified young stellar objects frequently show elongation, low density halos, and sub-clustering. The spatial distributions of protostars resemble the distribution of dense molecular gas, suggesting that their morphologies result directly from the fragmentation of the natal gas. We also examine the effects of the cluster environments on star and planet formation. Although Far-UV and Extreme-UV radiation from massive stars can truncate disks in a few million years, fewer than half of the young stars in our sample (embedded clusters within 1 kpc) are found in regions of strong FUV and EUV fields. Typical volume densities and lifetimes of the observed clusters suggest that dynamical interactions are not an important mechanism for truncating disks on solar system size scales.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 6,969 input tokens.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.23 · human participants 0.01 · controlled comparison 0.08 · randomized assignment 0.01 · states quantitative result 0.94 · compares with prior results 0.26 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; show every role.

We examine the properties of embedded clusters within 1 kiloparsec using new data from the Spitzer Space Telescope, as well as recent results from 2MASS and other ground-based near-infrared surveys. We use surveys of entire molecular clouds to understand the range and distribution of cluster membership, size and surface density. The Spitzer data demonstrate clearly that there is a continuum of star- forming environments, from relative isolation to dense clusters. The number of members of a cluster is correlated with the cluster radius, such that the average surface density of clusters having a few to a thousand members varies by a factor of only a few. The spatial distributions of Spitzer-identified young stellar objects frequently show elongation, low density halos, and sub-clustering. The spatial distributions of protostars resemble the distribution of dense molecular gas, suggesting that their morphologies result directly from the fragmentation of the natal gas. We also examine the effects of the cluster environments on star and planet formation. Although Far-UV and Extreme-UV radiation from massive stars can truncate disks in a few million years, fewer than half of the young stars in our sample (embedded clusters within 1 kpc) are found in regions of strong FUV and EUV fields. Typical volume densities and lifetimes of the observed clusters suggest that dynamical interactions are not an important mechanism for truncating disks on solar system size scales.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	We examine the properties of embedded clusters within 1 kiloparsec using new data from the Spitzer Space Telescope, as well as recent results from 2MASS and other ground-based near-infrared surveys.	method 0.60	0.87	0.03	asserted 0.75
s1	We use surveys of entire molecular clouds to understand the range and distribution of cluster membership, size and surface density.	method 0.95	0.81	0.03	asserted 0.75
s2	The Spitzer data demonstrate clearly that there is a continuum of star- forming environments, from relative isolation to dense clusters.	result 0.99	0.83	0.32	asserted 1.00
s3	The number of members of a cluster is correlated with the cluster radius, such that the average surface density of clusters having a few to a thousand members varies by a factor of only a few.	result 1.00	0.88	0.19	asserted 1.00
s4	The spatial distributions of Spitzer-identified young stellar objects frequently show elongation, low density halos, and sub-clustering.	result 1.00	0.89	0.07	asserted 1.00
s5	The spatial distributions of protostars resemble the distribution of dense molecular gas, suggesting that their morphologies result directly from the fragmentation of the natal gas.	interpretation 0.94	0.76	0.13	hedged possibility 0.99
s6	We also examine the effects of the cluster environments on star and planet formation.	contribution 0.99	0.85	0.03	unclear 0.93
s7	Although Far-UV and Extreme-UV radiation from massive stars can truncate disks in a few million years, fewer than half of the young stars in our sample (embedded clusters within 1 kpc) are found in regions of strong FUV and EUV fields.	result 1.00	0.90	0.12	asserted 0.95
s8	Typical volume densities and lifetimes of the observed clusters suggest that dynamical interactions are not an important mechanism for truncating disks on solar system size scales.	interpretation 0.80	0.81	0.18	asserted 0.81

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from analysis of existing data 0.63.

What was examined, and what was not

sources read

arXiv listing abstract v1

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

S sections
T body sentences
C citations
R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures

**Figure 1.** — Identifying and classifying young stars using near

**Figure 2.** — IRAC 4.5 µm and MIPS 24 µm images of IRAS4 in NGC 1333. MIPS detects each of the three VLA sources, while IRAC detects their outflows but not the driving sources. detect class II and class III objects, with perhaps some bias toward class III objects (Flacomio et al., 2003). The main limitation of X-ray observations is the lack of sensitivity toward lower mass stars. A complete sample of stars requires a sensitivity toward souces with luminosities as low as 1027 erg cm−2 s −1 (Feigelson et al., 2005), the sensitivity of most existing observations are an order of magnitude…

**Figure 3.** — IRAS 20050 surface densities derived from the stati

**Figure 4.** — The spatial distribution of all Spitzer identified i

**Figure 5.** — The distribution of the fraction of stars in clus

**Figure 7.** — The distribution of infrared excess sources in ten c

**Figure 8.** — The spatial distributions of Spitzer identified class I/0 (dark circles) and Class II (light circles) objects in four clusters: L1688 in Ophiuchus, Serpens, Mon R2 and IRAS 20050. The Class I/0 sources are often distributed along filamentary structures, while the Class II sources are more widely distributed. Many small groups of protostars are dense enough that interactions bewteen individual objects may occur. The manner in which a cluster spreads out and dissolves after its gas is removed is another important problem. After gas removal, clusters are expected to retain some…

Showing 7 of the paper's 8 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:astro-ph/0603096 by the authors.

References

Works cited (8)

[1]

Adams F. C. (2000) Astrophys. J., 542, 964-973. Adams F. C. and Laughlin G. (2001) Icarus, 150, 151-162. Adams F. C., Lada C. J., and Shu F. H. (1987) Astrophys. J., 312, 788-806. Adams F. C., Hollenbach D., Laughlin G., and Gorti U. (2004) Astrophys. J., 611, 360-379. Adams F. C., Proszkow E. M., Fatuzzo M., and Myers P. C. (2006) Astrophy. J., in press,...

View on Pith Pith review arXiv 2000
[378]

McMillan S. L. W. and Hut P. (1996)Astrophys. J., 467, 348-358. Megeath S. T., Herter T., Beichman C., Gautier N., Hester J. J ., Rayner J., and Shupe D. (1996) Astron. Astrophys., 307, 775-

View on Pith 1996
[409]

Flaherty K., Pipher J. L., Megeath S. T., Winston E. A., Gutermuth R. A., and Muzerolle J. (2006) in prep. Gladwin P. P., Kitsionas S., Bofﬁn H. M. J., and Whitworth A. P. (1999) Mon. Not. R. Astron. Soc., 302, 305-313. Gomez M., Hartmann L., Kenyon S. J., and Hewett R. (1993) As- tron. J., 105, 1927-1937. Greene T. P., Wilking B. A., Andr´ e, P., Young, ...

View on Pith 2006
[540]

Horner D. J., Lada E. A., and Lada C. J. (1997) Astron. J. 113 , 1788-1798. Huard T. (2006) private communication. Johnstone D., Hollenbach D. J., and Bally J. (1998) Astrophys. J., 499, 758-776. Kaas A. A. (1999) Astron. J., 118, 558-571. Kaas A. A., Olofsson G., Bontemps S., Andr´ e P., Nordh L. et al. (2004) Astron. Astrophys. 421, 623-642. Kobayashi H...

View on Pith 1997
[790]

Megeath S. T. and Wilson T. L. (1997)Astron. J., 114, 1106-1120. Megeath S. T., Biller B., Dame, T. M., Leass E., Whitaker R. S. , and Wilson T. L. (2002) Hot Star Workshop III: The Earliest Stages of MAssive Star Formation (P. A. Crowther, ed.), pp. 257-265. ASP Conf. Series, San Francisco. Megeath S. T., Allen L. E., Gutermuth R. A., Pipher J. L., Myer ...

View on Pith 1997
[1976]

Lada C. J., Muench A. A., Haisch K. E., Lada E. A., Alves J. F., Tollestrup E. V ., and Willner S. P. (2000) Astron. J., 120 , 3162-3176. Lada C. J. and Lada E. A. (2003) Ann. Rev. Astron. Astrophys., 41, 57-115. Lada C. J., Margulis M., and Dearborn D. (1984), Astrophys. J., 285, 141-152. Larson R. B. (1985) Mon. Not. R. Astron. Soc., 214 , 379-398. Leis...

View on Pith 2000
[2049]

Muzerolle J., Megeath S. T., Gutermuth R. A., Allen L. E., Pipher J. L. et al. (2004) Astrophys. J. Suppl., 154, 379-384. Muzerolle J., Megeath S. T., Flaherty K., Allen L. E., Young E. T. et al. (2006) in prep. Myers P. C. and Ladd E. F. (1993)Astrophys. J., 413, L47-L50. Nutter D. J., Ward-Thompson D., and Andr´ e P. (2005)Mon. Not. R. Astron. Soc., 357...

View on Pith Pith review arXiv 2004
[5073]

Hillenbrand L. A. (1995) Ph.D. Thesis, University of Mas- sachusetts. Hillenbrand L. A., Strom S. E., Vrba F. J., and Keene J. (1992) Astrophys. J., 397, 613-643. Hillenbrand L. A., Massey P., Strom S. E., and Merrill K. M. (1993) Astron. J., 106, 1906-1946. Hillenbrand L. A. and Hartmann L. (1998)Astrophys. J., 492,

View on Pith 1995

Forward citations

Cited by 4 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. OpenAlex reports about 6 citations worldwide. Full citation record

Long-term investigation of an open cluster Berkeley 65
astro-ph.SR 2025-05 conditional novelty 6.0 of 10

New photometric study of open cluster Berkeley 65 derives distance 2.0±0.1 kpc, age ~160 Myr, a mass function break near 1.7 solar masses, and a catalog of 80 variable stars, and argues the cluster is dynamically disrupted.
White dwarf planets in star clusters: gravitational scattering versus mass-loss effects
astro-ph.EP 2026-06 unverdicted novelty 5.0 of 10

N-body simulations find stellar mass-loss effects dominate gravitational scattering in altering giant planet orbits around white dwarfs formed in star clusters, independent of density and initial conditions.
Identifying and Determining Atmospheric Parameters of BHB Stars Based on LAMOST DR11
astro-ph.SR 2026-07 conditional novelty 4.0 of 10

A catalog of 13,988 BHB spectra (10,236 unique stars) from LAMOST DR11 with SLAM-based atmospheric parameters, using color indices to break the Teff–logg degeneracy.
Planet or brown dwarf? Constraints on the formation of H-type objects in IC348
astro-ph.EP 2026-06 unverdicted novelty 4.0 of 10

H-type objects in IC348 show spatial distributions matching stars and brown dwarfs, unlike the more dispersed distribution of simulated ejected planets, indicating a star-like formation origin.

How the literature uses it

6 arXiv papers cite this in 6 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 2 sentences without a confident label

Uses its method or tool 1 paper

* (J–H) vs. (H–K) c–c NIR diagram [ref] ; * K–[3.6] vs. [3.6]–[4.5] c–c diagram, which combines NIR and MIR photometric data [ref] ; * Spitzer MIR [3.6]-[4.5] vs. [5.8]-[8.0] and [3.6]-[5.8] vs. [8.0]-[24] c-c diagrams [ref] ; * WISE MIR [3.4]-[4.6] vs. [4.6]-[12] and [3.4]-[4.6] vs. [4.6]-[22] diagrams [ref] .

Searching for stellar population in the molecular cloud GRSMC 045.49+00.04 · Selection of young stellar population · 0.98

Cites it as support 1 paper

Thus, the density spectrum of stellar groups is continuous [ref] , and modern OB associations are not necessarily subject to global expansion [ref] .

Search for OB associations in {\sl Gaia} early Data Release 3 · Introduction · 0.96

Cites it as background 2 papers

Open clusters represent a very small proportion of birth clusters that remain gravitationally bound into the present day [ref] .

Testing the chemical homogeneity of chemically tagged dissolved birth clusters · Introduction · 0.87
Observations of present star formation show that stars form in a wide variety of environments from gravitationally-bound clusters to hierarchical structures and even in isolation [ref] .

The Age of the Carina Young Association and Potential Membership of HD 95086 · Cluster expansion · 0.81

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.

[1] [1]

Adams F. C. (2000) Astrophys. J., 542, 964-973. Adams F. C. and Laughlin G. (2001) Icarus, 150, 151-162. Adams F. C., Lada C. J., and Shu F. H. (1987) Astrophys. J., 312, 788-806. Adams F. C., Hollenbach D., Laughlin G., and Gorti U. (2004) Astrophys. J., 611, 360-379. Adams F. C., Proszkow E. M., Fatuzzo M., and Myers P. C. (2006) Astrophy. J., in press,...

View on Pith Pith review arXiv 2000

[2] [378]

McMillan S. L. W. and Hut P. (1996)Astrophys. J., 467, 348-358. Megeath S. T., Herter T., Beichman C., Gautier N., Hester J. J ., Rayner J., and Shupe D. (1996) Astron. Astrophys., 307, 775-

View on Pith 1996

[3] [409]

Flaherty K., Pipher J. L., Megeath S. T., Winston E. A., Gutermuth R. A., and Muzerolle J. (2006) in prep. Gladwin P. P., Kitsionas S., Bofﬁn H. M. J., and Whitworth A. P. (1999) Mon. Not. R. Astron. Soc., 302, 305-313. Gomez M., Hartmann L., Kenyon S. J., and Hewett R. (1993) As- tron. J., 105, 1927-1937. Greene T. P., Wilking B. A., Andr´ e, P., Young, ...

View on Pith 2006

[4] [540]

Horner D. J., Lada E. A., and Lada C. J. (1997) Astron. J. 113 , 1788-1798. Huard T. (2006) private communication. Johnstone D., Hollenbach D. J., and Bally J. (1998) Astrophys. J., 499, 758-776. Kaas A. A. (1999) Astron. J., 118, 558-571. Kaas A. A., Olofsson G., Bontemps S., Andr´ e P., Nordh L. et al. (2004) Astron. Astrophys. 421, 623-642. Kobayashi H...

View on Pith 1997

[5] [790]

Megeath S. T. and Wilson T. L. (1997)Astron. J., 114, 1106-1120. Megeath S. T., Biller B., Dame, T. M., Leass E., Whitaker R. S. , and Wilson T. L. (2002) Hot Star Workshop III: The Earliest Stages of MAssive Star Formation (P. A. Crowther, ed.), pp. 257-265. ASP Conf. Series, San Francisco. Megeath S. T., Allen L. E., Gutermuth R. A., Pipher J. L., Myer ...

View on Pith 1997

[6] [1976]

Lada C. J., Muench A. A., Haisch K. E., Lada E. A., Alves J. F., Tollestrup E. V ., and Willner S. P. (2000) Astron. J., 120 , 3162-3176. Lada C. J. and Lada E. A. (2003) Ann. Rev. Astron. Astrophys., 41, 57-115. Lada C. J., Margulis M., and Dearborn D. (1984), Astrophys. J., 285, 141-152. Larson R. B. (1985) Mon. Not. R. Astron. Soc., 214 , 379-398. Leis...

View on Pith 2000

[7] [2049]

Muzerolle J., Megeath S. T., Gutermuth R. A., Allen L. E., Pipher J. L. et al. (2004) Astrophys. J. Suppl., 154, 379-384. Muzerolle J., Megeath S. T., Flaherty K., Allen L. E., Young E. T. et al. (2006) in prep. Myers P. C. and Ladd E. F. (1993)Astrophys. J., 413, L47-L50. Nutter D. J., Ward-Thompson D., and Andr´ e P. (2005)Mon. Not. R. Astron. Soc., 357...

View on Pith Pith review arXiv 2004

[8] [5073]

Hillenbrand L. A. (1995) Ph.D. Thesis, University of Mas- sachusetts. Hillenbrand L. A., Strom S. E., Vrba F. J., and Keene J. (1992) Astrophys. J., 397, 613-643. Hillenbrand L. A., Massey P., Strom S. E., and Merrill K. M. (1993) Astron. J., 106, 1906-1946. Hillenbrand L. A. and Hartmann L. (1998)Astrophys. J., 492,

View on Pith 1995