Extremely Inefficient Star Formation in the Outer Disks of Nearby Galaxies

2); (2) MPIA Heidelberg; 3); (3) Nrao; (4) Univ. of Hertfordshire; (5) Univ. of Cape Town; (6) Carnegie Observatories); A. Leroy (2; B. Madore (6) ((1) UC Berkeley; E. Brinks (4)

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Extremely Inefficient Star Formation in the Outer Disks of Nearby Galaxies

F. Bigiel (1, 2), A. Leroy (2, 3), F. Walter (2), L. Blitz (1), E. Brinks (4), W.J.G. de Blok (5)

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B. Madore (6) ((1) UC Berkeley, (2) MPIA Heidelberg, (3) NRAO, (4) Univ. of Hertfordshire, (5) Univ. of Cape Town, (6) Carnegie Observatories)

Cosmology and Nongalactic Astrophysics · Submitted 20 Jul 2010

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim When compared with results from inside r25, we find outer disk star formation to be distinct in several ways: it is extremely inefficient (depletion times of many Hubble times) with column densities and SFRs lower than found anywhere inside the optical disks.

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arXiv ID1007.3498 (version 1)

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

Citation2), (2) MPIA Heidelberg, 3), (3) Nrao, (4) Univ. of Hertfordshire, (5) Univ. of Cape Town, (6) Carnegie Observatories), A. Leroy (2, B. Madore (6) ((1) UC Berkeley, E. Brinks (4), F. Bigiel (1, F. Walter (2), L. Blitz (1), W.J.G. de Blok (5). "Extremely Inefficient Star Formation in the Outer Disks of Nearby Galaxies." arXiv:1007.3498 (2010). https://pith.science/paper/MUZOGGEI

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The paper's own sentences, arranged. 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.

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What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.24 · human participants 0.01 · controlled comparison 0.51 · randomized assignment 0.01 · states quantitative result 0.96 · compares with prior results 0.91 · 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.

(Abridged) We combine data from The HI Nearby Galaxy Survey and the GALEX Nearby Galaxy Survey to study the relationship between atomic hydrogen (HI) and far-ultraviolet (FUV) emission outside the optical radius (r25) in 17 spiral and 5 dwarf galaxies. In this regime, HI is likely to represent most of the ISM and FUV emission to trace recent star formation with little bias due to extinction, so that the two quantities closely trace the underlying relationship between gas and star formation rate (SFR). The azimuthally averaged HI and FUV intensities both decline with increasing radius in this regime, with the scale length of the FUV profile typically half that of the HI profile. Despite the mismatch in profiles, there is a significant spatial correlation (at 15" resolution) between local FUV and HI intensities; near r25 this correlation is quite strong, in fact stronger than anywhere inside r25, and shows a decline towards larger radii. The star formation efficiency (SFE) - defined as the ratio of FUV/HI and thus the inverse of the gas depletion time - decreases with galactocentric radius across the outer disks, though much shallower than across the optical disks. On average, we find the gas depletion times to be well above a Hubble time (~10^11 yr). We observe a clear relationship between FUV/HI and HI column in the outer disks, with the SFE increasing with increasing HI column. Despite observing systematic variations in FUV/HI, we find no clear evidence for step-function type star formation thresholds. When compared with results from inside r25, we find outer disk star formation to be distinct in several ways: it is extremely inefficient (depletion times of many Hubble times) with column densities and SFRs lower than found anywhere inside the optical disks. It appears that the HI column is one of, perhaps even the key environmental factor in setting the SFR in outer galaxy disks.

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	(Abridged) We combine data from The HI Nearby Galaxy Survey and the GALEX Nearby Galaxy Survey to study the relationship between atomic hydrogen (HI) and far-ultraviolet (FUV) emission outside the optical radius (r25) in 17 spiral and 5 dwarf galaxies.	method 0.62	0.94	0.02	asserted 0.83
s1	In this regime, HI is likely to represent most of the ISM and FUV emission to trace recent star formation with little bias due to extinction, so that the two quantities closely trace the underlying relationship between gas and star formation rate (SFR).	interpretation 0.49	0.17	0.04	hedged possibility 0.99
s2	The azimuthally averaged HI and FUV intensities both decline with increasing radius in this regime, with the scale length of the FUV profile typically half that of the HI profile.	result 1.00	0.91	0.05	asserted 1.00
s3	Despite the mismatch in profiles, there is a significant spatial correlation (at 15" resolution) between local FUV and HI intensities; near r25 this correlation is quite strong, in fact stronger than anywhere inside r25, and shows a decline towards larger radii.	result 1.00	0.94	0.05	asserted 1.00
s4	The star formation efficiency (SFE) - defined as the ratio of FUV/HI and thus the inverse of the gas depletion time - decreases with galactocentric radius across the outer disks, though much shallower than across the optical disks.	result 1.00	0.94	0.21	asserted 1.00
s5	On average, we find the gas depletion times to be well above a Hubble time (~10^11 yr).	result 1.00	0.96	0.23	asserted 1.00
s6	We observe a clear relationship between FUV/HI and HI column in the outer disks, with the SFE increasing with increasing HI column.	result 1.00	0.96	0.09	asserted 1.00
s7	Despite observing systematic variations in FUV/HI, we find no clear evidence for step-function type star formation thresholds.	result 0.99	0.96	0.07	asserted 0.97
s8	When compared with results from inside r25, we find outer disk star formation to be distinct in several ways: it is extremely inefficient (depletion times of many Hubble times) with column densities and SFRs lower than found anywhere inside the optical disks.	result 0.99	0.96	0.72	asserted 1.00
s9	It appears that the HI column is one of, perhaps even the key environmental factor in setting the SFR in outer galaxy disks.	interpretation 1.00	0.70	0.40	hedged possibility 0.90

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from analysis of existing data 0.99.

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

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P abstract

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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

The paper

Original abstract

(Abridged) We combine data from The HI Nearby Galaxy Survey and the GALEX Nearby Galaxy Survey to study the relationship between atomic hydrogen (HI) and far-ultraviolet (FUV) emission outside the optical radius (r25) in 17 spiral and 5 dwarf galaxies. In this regime, HI is likely to represent most of the ISM and FUV emission to trace recent star formation with little bias due to extinction, so that the two quantities closely trace the underlying relationship between gas and star formation rate (SFR). The azimuthally averaged HI and FUV intensities both decline with increasing radius in this regime, with the scale length of the FUV profile typically half that of the HI profile. Despite the mismatch in profiles, there is a significant spatial correlation (at 15" resolution) between local FUV and HI intensities; near r25 this correlation is quite strong, in fact stronger than anywhere inside r25, and shows a decline towards larger radii. The star formation efficiency (SFE) - defined as the ratio of FUV/HI and thus the inverse of the gas depletion time - decreases with galactocentric radius across the outer disks, though much shallower than across the optical disks. On average, we find the gas depletion times to be well above a Hubble time (~10^11 yr). We observe a clear relationship between FUV/HI and HI column in the outer disks, with the SFE increasing with increasing HI column. Despite observing systematic variations in FUV/HI, we find no clear evidence for step-function type star formation thresholds. When compared with results from inside r25, we find outer disk star formation to be distinct in several ways: it is extremely inefficient (depletion times of many Hubble times) with column densities and SFRs lower than found anywhere inside the optical disks. It appears that the HI column is one of, perhaps even the key environmental factor in setting the SFR in outer galaxy disks.

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References

Forward citations

Cited by 7 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

Survival is not Enough: Dust Sputtering, Growth, and H$_2$ Formation in Galactic Winds
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The origin and distribution of diffuse HI in the close interacting MHONGOOSE galaxy systems
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Deep hydrogen maps of two close galaxy systems reveal diffuse tidal gas redistributed by mild fly-bys while galaxy disks stay intact, plus a record-low-mass gas-poor dwarf galaxy.
FEAST: Spatially Resolved Star Formation History of the NGC 4485/NGC 4490 System and its Tidal Bridge from JWST/NIRCam Color Magnitude Diagrams
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The resolved star formation history of NGC 4485/4490 shows two system-wide bursts, peaking near 500-800 Myr and 10-30 Myr ago, that the authors link to the pair's two predicted close encounters.
Chemical complexity in feedback from supernova remnants: first detection of PO+ in IC443 and W44
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First detection of PO+ toward supernova remnants IC443 and W44, with PO+/PN ratios of at least 1 to 5, suggesting SNR shocks shift phosphorus chemistry toward an ion-dominated regime.
RIGEL: Ultra-faint dwarf galaxy diversity shaped by inhomogeneous cosmic reionization
astro-ph.GA 2026-09 accept novelty 6.0 of 10

Simulations with realistic patchy reionization show that the diversity of ultra-faint dwarf galaxies is primarily controlled by the halo mass at the moment of reionization.

Show 2 more citing papers

A Multiwavelength Inventory for the Local Group L-band Survey I: Atlas and Radial Profiles of Local Group Galaxies
astro-ph.GA 2026-07 conditional novelty 6.0 of 10

Atomic gas is the most extended component in six Local Group galaxies, and atomic-gas depletion times rise from about 1 Gyr in the inner disks to tens-to-hundreds of Gyr in the outer disks.
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.

How later papers used it

75 later papers cite it

Evidence: substantial. 62 of the citing papers share no author with it, and 26 of those carry a confident label from Pith's citation classifier.

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1 later paper by other authors is listed below: 1 compared its own results with it. 1 more paper by the same authors is listed: 1 used its method or tool.

Uses its method or tool 1 of 4 papers with this label · 1 by the same authors

By the same authors

Converted measured FUV intensities into star formation rate surface densities, assuming FUV emission arises mostly from young massive stars forming at a steady rate, using this paper's approach.

Tightly Correlated HI and FUV Emission in the Outskirts of M83 (2010) (same authors) · 1.00 · paraphrased: the licence does not allow quoting

Compares with it 1 of 21 papers with this label

Compared its own runaway model's feature with measurements of star formation in outer regions of observed spiral galaxies from this paper, finding a striking similarity.

Runaway stars masquerading as star formation in galactic outskirts (2020) · 1.00 · paraphrased: the licence does not allow quoting

How the literature uses it

6 arXiv papers cite this in 8 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 · 4 sentences without a confident label

Uses its method or tool 1 paper

Assuming FUV emission to arise mostly from young massive stars forming at a steady rate, we can convert the measured FUV intensities into star formation rate surface densities, $Σ_SFR$ [ref] .

Tightly Correlated HI and FUV Emission in the Outskirts of M83 · Radial Trends · 1.00

Uses its data or values 1 paper

Observational data from [ref] , [ref] , [ref] , [ref] , and [ref] correspond to pixel-wise measurements of sizes $1$, $0.75$, $0.6$, $1$ and $0.3$ kpc, respectively.

Kennicutt-Schmidt relation of galaxies over 13 billion years in the COLIBRE hydrodynamical simulations · KS relation: comparison with observations and characterisation · 0.84

Compares with it 1 paper

For the total neutral hydrogen, we find that 's predictions are in between the observational estimates at surface densities $≲10^1.5 M_⊙ pc^-2$, while at higher densities, there is agreement with [ref] , which is the only data set available at those surface densities.

Kennicutt-Schmidt relation of galaxies over 13 billion years in the COLIBRE hydrodynamical simulations · KS relation: comparison with observations and characterisation · 0.94

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