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Black-hole-triggered star formation in the dwarf galaxy Henize 2-10


Black-hole-driven outflows have been observed in some dwarf galaxies with active galactic nuclei1, and probably play a role in heating and expelling gas (thereby suppressing star formation), as they do in larger galaxies2. The extent to which black-hole outflows can trigger star formation in dwarf galaxies is unclear, because work in this area has previously focused on massive galaxies and the observational evidence is scarce3,4,5. Henize 2-10 is a dwarf starburst galaxy previously reported to have a central massive black hole6,7,8,9, although that interpretation has been disputed because some aspects of the observational evidence are also consistent with a supernova remnant10,11. At a distance of approximately 9 Mpc, it presents an opportunity to resolve the central region and to determine if there is evidence for a black-hole outflow influencing star formation. Here we report optical observations of Henize 2-10 with a linear resolution of a few parsecs. We find an approximately 150-pc-long ionized filament connecting the region of the black hole with a site of recent star formation. Spectroscopy reveals a sinusoid-like position–velocity structure that is well described by a simple precessing bipolar outflow. We conclude that this black-hole outflow triggered the star formation.

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Fig. 1: HST optical image of the dwarf starburst galaxy Henize 2-10.
Fig. 2: Optical spectra and ionized gas kinematics for the central region of Henize 2-10.
Fig. 3: Visualization of the bipolar outflow model and star-forming regions.

Data availability

The spectroscopic data analysed in this study are available from the Mikulski Archive for Space Telescopes (MAST) at


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We are grateful to M. Molina for useful discussions regarding shocks. We also thank M. Whittle and K. Johnson for their assistance with the HST/STIS proposal while A.E.R. was a graduate student at the University of Virginia, and for subsequent discussions. Support for Program number HST-GO-12584.006-A was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. A.E.R. also acknowledges support for this work provided by NASA through EPSCoR grant number 80NSSC20M0231. Z.S. acknowledges support for this project from the Montana Space Grant Consortium.

Author information

Authors and Affiliations



Z.S. reduced and analysed the STIS data and compared the results with models. A.E.R. led the HST/STIS proposal and helped with the data reduction. Both authors worked on the interpretation of the results and the writing of the paper.

Corresponding author

Correspondence to Zachary Schutte.

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Extended data figures and tables

Extended Data Fig. 1 Raw 2D spectra showing the [OI]6300 emission line at the location of the nucleus in the EW slit orientation.

The location of the nucleus is indicated by white circles and the two images correspond to the two dithered sub-exposures.

Extended Data Fig. 2 Combined 2D spectra showing the [OI]6300 emission line at the location of the nucleus in the EW slit orientation.

Same as Extended Data Fig. 1 but showing the reduced 2D image with the dithered sub-exposures combined.

Extended Data Fig. 3 The electron density, ne, along the EW slit orientation.

We measure the electron density along the EW slit from the ratio of [SII]6716/[SII]6731 and find the electron density ranges from \(\sim {10}^{2.5}-{10}^{4}\) cm−3, which is within the range the [SII] ratio is sensitive to density. The high densities are consistent with those predicted by optical emission line diagnostics derived from the Allen et al.25 shock models.

Extended Data Fig. 4 The spatial extraction regions taken along the EW slit orientation.

We place these regions on optical emission line diagnostic diagrams (Extended Data Figs. 57). Top panel: the extraction regions are shown on the narrow band H\(\alpha \) + continuum image from HST to highlight the ionized gas features that several of the spatial extractions probe. Bottom panel: the extraction regions are shown on the archival 0.8 micron HST image, showing young star clusters that the EW slit orientation passes through.

Extended Data Fig. 5 Narrow emission line diagnostic diagrams showing various extraction regions along the EW slit orientation (see Extended Data Fig. 4).

The nucleus (yellow point) falls in the Seyfert region of the [OI]/H\(\alpha \) diagram. The young star-forming region ~70 pc to the east of the low-luminosity AGN is depicted with a blue triangle and star for the primary emission line component and the blue-shifted secondary component, respectively. [OI] is not detected in all of the regions.

Extended Data Fig. 6 Optical emission line diagnostics from the shock and shock+precursor models with varying gas density.

We place the spatial extractions from the EW slit orientation shown in Extended Data Fig. 4 on a grid of shock excitation models (presented in Allen et al.25 with varying gas density (n = 0.01-1000 \({\mathrm{cm}}^{-3}\)) and shock velocity (v = 100-600 km/s). We fix the transverse magnetic field to be b = \(1{\rm{\mu }}\)G and the assume solar metallicity.

Extended Data Fig. 7 Optical emission line diagnostics from the shock and shock+precursor models with varying magnetic field.

The models (presented in Allen et al.25) are shown as a grid with dashed blue lines indicating constant shock velocity and dashed black lines indicating constant transverse magnetic field. For these models, the density is fixed to n = 1000 \({\mathrm{cm}}^{-3}\) and the transverse magnetic field parameter is allowed to vary from b = 0.01-32 \({\rm{\mu }}\)G.

Extended Data Fig. 8 A diagram of the toy model of the bipolar outflow generated by the low-luminosity AGN in Henize 2-10.

Our simple model depends on the outflow velocity of the ionized gas (\({v}_{{outflow}}\)), the angle the outflow makes with its precession axis (\(\theta \)) and the angular frequency with which the outflow precesses (\(\omega \)). Similar models have been used to describe the bending seen in large radio jets15,16.

Extended Data Table 1 Summary of observational results regarding the nature of the nucleus in Henize 2-10

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Schutte, Z., Reines, A.E. Black-hole-triggered star formation in the dwarf galaxy Henize 2-10. Nature 601, 329–333 (2022).

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