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<jats:title>Abstract</jats:title> <jats:p>We searched for shocked carbon chain chemistry (SCCC) sources with C<jats:sub>3</jats:sub>S abundances surpassing those of HC<jats:sub>5</jats:sub>N toward the dark cloud L1251, using the Effelsberg telescope at the <jats:italic>K </jats:italic>band (18–26 GHz). L1251-1 and L1251-3 are identified as the most promising SCCC sources. The two sources harbor young stellar objects. We conducted mapping observations toward L1251-A, the western tail of L1251, at <jats:italic>λ</jats:italic> ∼ 3 mm with the Purple Mountain Observatory 13.7 m and the Nobeyama Radio Observatory 45 m telescopes in lines of C<jats:sub>2</jats:sub>H, N<jats:sub>2</jats:sub>H<jats:sup>+</jats:sup>, CS, HCO<jats:sup>+</jats:sup>, SO, HC<jats:sub>3</jats:sub>N, and C<jats:sup>18</jats:sup>O as well as in CO 3–2 using the James Clerk Maxwell Telescope (JCMT). The spectral data were combined with archival data including Spitzer and Herschel continuum maps for further analysis. Filamentary substructures labeled as F1–F6 were extracted in L1251, with F1 being associated with L1251-A hosting L1251-1. The peak positions of dense gas traced by HCO<jats:sup>+</jats:sup> are misaligned relative to those of the dust clumps. Episodic outflows are common in this region. The twisted morphology of F1 and velocity distribution along L1251-A may originate from stellar feedback. SCCC in L1251-1 may have been caused by outflow activities originated from the infrared source IRS1. The signposts of ongoing SCCC and the broadened line widths of C<jats:sub>3</jats:sub>S and C<jats:sub>4</jats:sub>H in L1251-1 as well as the distribution of HC<jats:sub>3</jats:sub>N are also related to outflow activities in this region. L1251-1 (IRS1) together with the previously identified SCCC source IRS3 demonstrate that L1251-A is an excellent region to study SCCC.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In our companion paper (Brought to Light I: Michea et al.), we reveal spectacular spiral-galaxy-like features in deep optical imaging of nine Virgo early-type dwarf galaxies, hidden beneath a dominating smooth stellar disk. Using a new combination of approaches, we find that bar- and spiral-like features contribute 2.2%–6.4% of the total flux within 2 <jats:italic>R</jats:italic> <jats:sub>eff</jats:sub>. In this study, we conduct high-resolution simulations of cluster harassment of passive dwarf galaxies. Following close pericenter passages of the cluster core, tidal triggering generates features in our model disks that bear a striking resemblance to the observed features. However, we find the disks must be highly rotationally supported (<jats:italic>V</jats:italic> <jats:sub>peak</jats:sub>/<jats:italic>σ</jats:italic> <jats:sub>0</jats:sub> ∼ 3), much higher than typically observed. We propose that some early-type dwarfs may contain a few percent of their mass in a cold, thin disk that is buried in the light of a hot, diffuse disk and only revealed when they undergo tidal triggering. The red optical colors of our sample do not indicate any recent significant star formation, and our simulations show that very plunging pericenter passages (<jats:italic>r</jats:italic> <jats:sub>peri</jats:sub> &lt; 0.25<jats:italic>r</jats:italic> <jats:sub>vir</jats:sub>) are required for tidal triggering. Thus, many cluster early-type dwarfs with less-plunging orbits may host a yet-undetected cold stellar disk component. We discuss possible origin scenarios and consider why similar-mass star-forming galaxies in the field are significantly more thin-disk dominated than in our cluster sample.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Hubble constant (<jats:italic>H</jats:italic> <jats:sub>0</jats:sub>) tension between Type Ia supernovae (SNe Ia) and Planck measurements ranges from 4 to 6<jats:italic>σ</jats:italic>. To investigate this tension, we estimate <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> in the ΛCDM and <jats:inline-formula> <jats:tex-math> <?CDATA ${w}_{0}{w}_{a}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>w</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:msub> <mml:mrow> <mml:mi>w</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>CDM (cold dark matter) models by dividing the Pantheon sample, the largest compilation of SNe Ia, into 3, 4, 20, and 40 bins. We fit the extracted <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> values with a function mimicking the redshift evolution: <jats:inline-formula> <jats:tex-math> <?CDATA $g{(z)={H}_{0}(z)={\tilde{H}}_{0}/(1+z)}^{\alpha }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>g</mml:mi> <mml:msup> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>z</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mi>z</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>˜</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo> <mml:mi>z</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mi>α</mml:mi> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, where <jats:italic>α</jats:italic> indicates an evolutionary parameter and <jats:inline-formula> <jats:tex-math> <?CDATA ${\tilde{H}}_{0}={H}_{0}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>˜</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> at <jats:italic>z</jats:italic> = 0. We set the absolute magnitude of SNe Ia so that <jats:inline-formula> <jats:tex-math> <?CDATA ${H}_{0}\,=73.5\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mspace width="0.25em" /> <mml:mo>=</mml:mo> <mml:mn>73.5</mml:mn> <mml:mspace width="0.25em" /> <mml:mi>km</mml:mi> <mml:mspace width="0.25em" /> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em" /> <mml:msup> <mml:mrow> <mml:mi>Mpc</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>, and we fix fiducial values for <jats:inline-formula> <jats:tex-math> <?CDATA ${{\rm{\Omega }}}_{0m}^{{\rm{\Lambda }}\mathrm{CDM}}=0.298$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">Ω</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">Λ</mml:mi> <mml:mi>CDM</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>=</mml:mo> <mml:mn>0.298</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA ${{\rm{\Omega }}}_{0m}^{{w}_{0}{w}_{a}\mathrm{CDM}}=0.308$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">Ω</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>w</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:msub> <mml:mrow> <mml:mi>w</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> </mml:msub> <mml:mi>CDM</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>=</mml:mo> <mml:mn>0.308</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn6.gif" xlink:type="simple" /> </jats:inline-formula>. We find that <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> evolves with redshift, showing a slowly decreasing trend, with <jats:italic>α</jats:italic> coefficients consistent with zero only from 1.2 to 2.0<jats:italic>σ</jats:italic>. Although the <jats:italic>α</jats:italic> coefficients are compatible with zero in 3<jats:italic>σ</jats:italic>, this however may affect cosmological results. We measure locally a variation of <jats:inline-formula> <jats:tex-math> <?CDATA ${H}_{0}(z=0)-{H}_{0}(z=1)=0.4\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mi>z</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> <mml:mo>−</mml:mo> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mi>z</mml:mi> <mml:mo>=</mml:mo> <mml:mn>1</mml:mn> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:mn>0.4</mml:mn> <mml:mspace width="0.25em" /> <mml:mi>km</mml:mi> <mml:mspace width="0.25em" /> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em" /> <mml:msup> <mml:mrow> <mml:mi>Mpc</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn7.gif" xlink:type="simple" /> </jats:inline-formula> in three and four bins. Extrapolating <jats:inline-formula> <jats:tex-math> <?CDATA ${H}_{0}(z)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mi>z</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn8.gif" xlink:type="simple" /> </jats:inline-formula> to <jats:italic>z</jats:italic> = 1100, the redshift of the last scattering surface, we obtain values of <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> compatible in 1<jats:italic>σ</jats:italic> with Planck measurements independent of the cosmological models and number of bins we investigated. Thus, we have reduced the <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> tension in the range from 54% to 72% for both cosmological models. If the decreasing trend of <jats:inline-formula> <jats:tex-math> <?CDATA ${H}_{0}(z)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mi>z</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabeb73ieqn9.gif" xlink:type="simple" /> </jats:inline-formula> is real, it could be due to astrophysical selection effects or to modified gravity.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Following a tidal disruption event (TDE), the accretion rate can evolve from quiescent to near-Eddington levels and back over timescales of months to years. This provides a unique opportunity to study the formation and evolution of the accretion flow around supermassive black holes (SMBHs). We present 2 yr of multiwavelength monitoring observations of the TDE AT2018fyk at X-ray, UV, optical, and radio wavelengths. We identify three distinct accretion states and two state transitions between them. These appear remarkably similar to the behavior of stellar-mass black holes in outburst. The X-ray spectral properties show a transition from a soft (thermal-dominated) to a hard (power-law-dominated) spectral state around <jats:italic>L</jats:italic> <jats:sub>bol</jats:sub> ∼ few × 10<jats:sup>−2</jats:sup> <jats:italic>L</jats:italic> <jats:sub>Edd</jats:sub> and the strengthening of the corona over time ∼100–200 days after the UV/optical peak. Contemporaneously, the spectral energy distribution (in particular, the UV to X-ray spectral slope <jats:italic>α</jats:italic> <jats:sub>ox</jats:sub>) shows a pronounced softening as the outburst progresses. The X-ray timing properties also show a marked change, initially dominated by variability at long (&gt;day) timescales, while a high-frequency (∼10<jats:sup>−3</jats:sup> Hz) component emerges after the transition into the hard state. At late times (∼500 days after peak), a second accretion state transition occurs, from the hard into the quiescent state, as identified by the sudden collapse of the bolometric (X-ray+UV) emission to levels below 10<jats:sup>−3.4</jats:sup> <jats:italic>L</jats:italic> <jats:sub>Edd</jats:sub>. Our findings illustrate that TDEs can be used to study the scale (in)variance of accretion processes in individual SMBHs. Consequently, they provide a new avenue to study accretion states over seven orders of magnitude in black hole mass, removing limitations inherent to commonly used ensemble studies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Modeling collisionless magnetic reconnection rate is an outstanding challenge in basic plasma physics research. While the seemingly universal rate of an order <jats:inline-formula> <jats:tex-math> <?CDATA ${ \mathcal O }(0.1)$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabf48cieqn1.gif" xlink:type="simple" /> </jats:inline-formula> is often reported in the low-<jats:italic>β</jats:italic> regime, it is not clear how reconnection rate scales with a higher plasma <jats:italic>β</jats:italic>. Due to the complexity of the pressure tensor, the available reconnection rate model is limited to the low plasma-<jats:italic>β</jats:italic> regime, where the thermal pressure is arguably negligible. However, the thermal pressure effect becomes important when <jats:inline-formula> <jats:tex-math> <?CDATA $\beta \gtrsim { \mathcal O }(1)$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabf48cieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. Using first-principle kinetic simulations, we show that both the reconnection rate and outflow speed drop as <jats:italic>β</jats:italic> gets larger. A simple analytical framework is derived to take account of the self-generated pressure anisotropy and pressure gradient in the force balance around the diffusion region, explaining the varying trend of key quantities and reconnection rates in these simulations with different <jats:italic>β</jats:italic>. The predicted scaling of the normalized reconnection rate is <jats:inline-formula> <jats:tex-math> <?CDATA $\simeq { \mathcal O }(0.1/\sqrt{{\beta }_{i0}})$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabf48cieqn3.gif" xlink:type="simple" /> </jats:inline-formula> in the high-<jats:italic>β</jats:italic> limit, where <jats:italic>β</jats:italic> <jats:sub> <jats:italic>i</jats:italic>0</jats:sub> is the ion <jats:italic>β</jats:italic> of the inflow plasma.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>While solar flares are predominantly characterized by an intense broadband enhancement to the solar radiative output, certain spectral lines and continua will, in theory, exhibit flare-induced dimmings. Observations of transitions of orthohelium He <jats:sc>i</jats:sc> <jats:italic>λ</jats:italic> <jats:italic>λ</jats:italic> 10830 Å and the He <jats:sc>i</jats:sc> D3 lines have shown evidence of such dimming, usually followed by enhanced emission. It has been suggested that nonthermal collisional ionization of helium by an electron beam, followed by recombinations to orthohelium, is responsible for overpopulating those levels, leading to stronger absorption. However, it has not been possible observationally to preclude the possibility of overpopulating orthohelium via enhanced photoionization of He <jats:sc>i</jats:sc> by EUV irradiance from the flaring corona followed by recombinations. Here we present radiation hydrodynamics simulations of nonthermal electron-beam-driven flares where (1) both nonthermal collisional ionization of helium and coronal irradiance are included, and (2) only coronal irradiance is included. A grid of simulations covering a range of total energies deposited by the electron beam and a range of nonthermal electron-beam low-energy cutoff values were simulated. In order to obtain flare-induced dimming of the He <jats:sc>i</jats:sc> 10830 Å line, it was necessary for nonthermal collisional ionization to be present. The effect was more prominent in flares with larger low-energy cutoff values and longer lived in weaker flares and flares with a more gradual energy deposition timescale. These results demonstrate the usefulness of orthohelium line emission as a diagnostic of flare energy transport.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The boundaries identification of Kelvin–Helmholtz vortices in observational data has been addressed by searching for single-spacecraft small-scale signatures. A recent hybrid Vlasov–Maxwell simulation of Kelvin–Helmholtz instability has pointed out clear kinetic features that uniquely characterize the vortex during both the nonlinear and turbulent stage of the instability. We compare the simulation results with in situ observations of Kelvin–Helmholtz vortices by the Magnetospheric Multiscale satellites. We find good agreement between simulation and observations. In particular, the edges of the vortex are associated with strong current sheets, while the center is characterized by a low value for the magnitude of the total current density and strong deviation of the ion distribution function from a Maxwellian distribution. We also find a significant temperature anisotropy parallel to the magnetic field inside the vortex region and strong agyrotropies near the edges. We suggest that these kinetic features can be useful for the identification of Kelvin–Helmholtz vortices in in situ data.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Understanding the escape of ionizing (Lyman continuum) photons from galaxies is vital for determining how galaxies contributed to reionization in the early universe. While directly detecting the Lyman continuum from high-redshift galaxies is impossible due to the intergalactic medium, low-redshift galaxies in principle offer this possibility but require observations from space. The first local galaxy for which Lyman continuum escape was found is Haro 11, a luminous blue compact galaxy at <jats:italic>z</jats:italic> = 0.02, where observations with the FUSE satellite revealed an escape fraction of 3.3%. However, the FUSE aperture covers the entire galaxy, and it is not clear from where the Lyman continuum is leaking out. Here we utilize Hubble Space Telescope/Cosmic Origins Spectrograph spectroscopy in the wavelength range 1100–1700 Å of the three knots (A, B, and C) of Haro 11 to study the presence of Ly<jats:italic>α</jats:italic> emission and the properties of intervening gas. We find that all knots have bright Ly<jats:italic>α</jats:italic> emission. UV absorption lines, originating in the neutral interstellar medium, as well as lines probing the ionized medium, are seen extending to blueshifted velocities of 500 km s<jats:sup>−1</jats:sup> in all three knots, demonstrating the presence of an outflowing multiphase medium. We find that knots A and B have large covering fractions of neutral gas, making LyC escape along these sightlines improbable, while knot C has a much lower covering fraction (≲50%). Knot C also has the the highest Ly<jats:italic>α</jats:italic> escape fraction, and we conclude that it is the most likely source of the escaping Lyman continuum detected in Haro 11.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A sample of 1.3 mm continuum cores in the Dragon infrared dark cloud (also known as G28.37+0.07 or G28.34+0.06) is analyzed statistically. Based on their association with molecular outflows, the sample is divided into protostellar and starless cores. Statistical tests suggest that the protostellar cores are more massive than the starless cores, even after temperature and opacity biases are accounted for. We suggest that the mass difference indicates core mass growth since their formation. The mass growth implies that massive star formation may not have to start with massive prestellar cores, depending on the core mass growth rate. Its impact on the relation between core mass function and stellar initial mass function is to be further explored.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present and discuss three extremely r-process enhanced stars located in the massive dwarf spheroidal galaxy Fornax. These stars are very unique with an extreme Eu enrichment (1.25 ≤ [Eu/Fe]≤1.45) at high metallicities (−1.3 ≤ [Fe/H]≤−0.8). They have the largest Eu abundances ever observed in a dwarf galaxy opening new opportunities to further understand the origin of heavy elements formed by the r-process. We derive stellar abundances of Co, Zr, La, Ce, Pr, Nd, Er, and Lu using one-dimensional, local thermodynamic equilibrium codes and model atmospheres in conjunction with state-of-the art yield predictions. We derive Zr in the largest sample of stars (105) known to date in a dwarf galaxy. Accurate stellar abundances combined with a careful assessment of the yield predictions have revealed three metal-rich stars in Fornax showing a pure r-process pattern. We define a new class of stars, namely, Eu-stars, as r-II stars (i.e., [Eu/Fe] &gt; 1) at high metallicities (i.e., [Fe/H] ≳ −1.5). The stellar abundance pattern contains Lu, observed for the first time in a dwarf galaxy, and reveals that a late burst of star formation has facilitated extreme r-process enhancement late in the galaxy’s history (&lt;4 Gyr ago). Due to the large uncertainties associated with the nuclear physics input in the yield predictions, we cannot yet determine the r-process site leading to the three Eu-stars in Fornax. Our results demonstrate that extremely r-rich stars are not only associated with ultra-faint low-mass dwarf galaxies, but can be born also in massive dwarf galaxies.</jats:p>