New Insights into the Formation of the Blue Main Sequence in NGC 1850

Yang, Yujiao; Li, Chengyuan; Deng, Licai; Grijs, Richard de; Milone, A. P.

doi:10.3847/1538-4357/aabe26

Cited by 12 publications

(13 citation statements)

References 34 publications

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“…Following a similar procedure to Saracino et al (2021), we compared the object's HST/WFC3 photometry to a grid of MIST isochrones (Choi et al 2016). We assumed a distance modulus of (𝑚 − 𝑀) 0 = 18.40 ± 0.05 mag, extinction 𝐴 𝑉 = 0.35 ± 0.1 mag, and metallicity [Fe/H] = −0.3 (Bastian et al 2016;Yang et al 2018), with a Cardelli et al (1989) extinction law with 𝑅 𝑉 = 3.1.…”

Section: Radius Of the Rv-variable Starmentioning

confidence: 99%

NGC 1850 BH1 is another stripped-star binary masquerading as a black hole

El-Badry,

Burdge

2021

Preprint

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We show that the radial velocity-variable star in the black hole candidate NGC 1850 BH1 cannot be a normal ∼ 5 𝑀 subgiant, as was proposed, but is an overluminous stripped-envelope star with mass ∼ 1𝑀 . The result follows directly from the star's observed radius and the orbital period -density relation for Roche lobe-filling stars: the star's density, as constrained by the observed ellipsoidal variability, is too low for its mass to exceed ∼ 1.5 𝑀 . This lower mass significantly reduces the implied mass of the unseen companion and qualitative interpretation of the system, such that a normal main-sequence companion with mass (2.5 − 5) 𝑀 is fully consistent with the data. We explore evolutionary scenarios that could produce the binary using MESA and find that its properties can be matched by models in which a ∼ 5 𝑀 primary loses most of its envelope to a companion and is observed in a bloated state before contracting to become a core helium burning sdOB star. This is similar to the scenario proposed to explain the binaries LB-1 and HR 6819. Though it likely does not contain a black hole, NGC 1850 BH1 provides an interesting test case for binary evolution models, particularly given its membership in a cluster of known age.

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Section: Radius Of the Rv-variable Starmentioning

confidence: 99%

NGC 1850 BH1 is another stripped-star binary masquerading as a black hole

El-Badry,

Burdge

2021

Preprint

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“…Recently, Somboonpanyakul et al (2018) found through Chandra imaging, that the bright X-ray emitting AGN masqueraded the presence of a massive extended X-ray cool-core galaxy cluster. The discovery was the outcome of their targeted search for over-densities of red galaxies around such ROSAT -detected AGN (see also, Green et al 2017;Yang et al 2018), and confirmed the underlying cluster indicated by the spatially coincident Planck Sunyaev-Zeldovich source PSZ2 G317.79+26.63 (offset of 1.7 from the radio position, thus within the 95% confidence error of 2.4 ; Planck Collaboration 2016). Thus PKS 1353-341 can now be classified as the brightest cluster galaxy (BCG) hosting a radioand X-ray bright AGN at the center of a luminous X-ray cluster.…”

Section: Introductionmentioning

confidence: 60%

Extended Radio Structures and a Compact X-Ray Cool-core in the Cluster Source PKS 1353–341

Cheung

Giacintucci

2019

ApJ

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We present a radio and X-ray study of PKS 1353-341, the brightest cluster galaxy radio source at the center of a recent Chandra-discovered X-ray cluster. Our multi-frequency VLA images reveal an edge-brightened (FR-II), double-lobed structure with total ∼50 kpc extent and 1.5 GHz power of 1.2 × 10 25 W Hz −1 , separated from the bright, arcsecond-scale core. We reanalyzed the Chandra data and found the X-ray emitting AGN is offset by ∼9 kpc from a compact X-ray cool-core with temperature, kT = 3.1 ± 0.5 keV, and a radius of ∼22 kpc, surrounded by a hotter kT = 6.3 ± 0.7 keV gas out to ∼50 kpc. The offset suggests sloshing inside the cool-core induced by a minor merger or a past outburst of the AGN that produced the large-scale radio lobes. The comparable spatial scales of the lobes with the interface between the different temperature X-ray plasma indicate the lobes are actively heating the outer layers of what is now a remnant compact cool-core. Our dual-frequency VLBA images reveal substructure in the central radio source, consisting of a radio core with double-sided pc-scale jets pointing toward the kpc-scale structures. The northern jet is detected only at 8.4 GHz, indicating its emission is behind an absorbing torus or disk. We also measured faster apparent motions in the southern jet up to 1.9 ± 1.1c than in the northern jet (0.8 ± 0.5c). While the VLBA observations indicate the southern jet is aligned slightly closer to our line of sight, the asymmetries are overall modest and imply minimal projection effects in the large-scale radio structures.

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“…This method compares the CMD of the cluster region with that of its reference field and statistically subtracts stars from the cluster CMD by assuming that field stars will have the same color-magnitude distribution in the cluster region. This method has been widely used for LMC clusters (e.g., Milone et al 2018;Yang et al 2018). However, it cannot be directly applied in this paper, because (1) both the numbers of genuine cluster members and contaminating field stars are very small in the BSS regions.…”

Section: Resultsmentioning

confidence: 99%

Blue Straggler Stars beyond the Milky Way. IV. Radial Distributions and Dynamical Implications

Sun

Deng

et al. 2019

ApJ

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Blue straggler stars have been proposeed as powerful indicators to measure the dynamical state of Galactic globular clusters. Here we examine for the first time if this framework of blue straggler stars as dynamical clocks, which was specifically developed for Galactic globular clusters, may also hold for younger globular clusters in the Large Magellanic Cloud. Using Hubble Space Telescope observations, we study seven Large Magellanic Cloud star clusters with ages between ∼700 Myr and 7 Gyr. We confirm that our sample clusters are consistent with the empirical correlation previously derived for Galactic globular clusters, within a modest tolerance. We suggest that to further examine if blue straggler stars can measure the dynamical state of their host clusters over an extended range of dynamical ages, more studies of dynamically older Magellanic Cloud clusters are required. We discuss the physical implications of our results in terms of their central, dimensionless King potential, as well as the initial retention fraction of black holes.

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New Insights into the Formation of the Blue Main Sequence in NGC 1850

Cited by 12 publications

References 34 publications

NGC 1850 BH1 is another stripped-star binary masquerading as a black hole

NGC 1850 BH1 is another stripped-star binary masquerading as a black hole

Extended Radio Structures and a Compact X-Ray Cool-core in the Cluster Source PKS 1353–341

Blue Straggler Stars beyond the Milky Way. IV. Radial Distributions and Dynamical Implications

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