dc.creator | Dixon, William V. | |
dc.creator | Chayer, Pierre | |
dc.creator | Latour, Marilyn | |
dc.creator | Miller Bertolami, Marcelo Miguel | |
dc.creator | Benjamin, Robert A. | |
dc.date.accessioned | 2018-04-19T12:26:34Z | |
dc.date.accessioned | 2018-11-06T12:17:09Z | |
dc.date.available | 2018-04-19T12:26:34Z | |
dc.date.available | 2018-11-06T12:17:09Z | |
dc.date.created | 2018-04-19T12:26:34Z | |
dc.date.issued | 2017-09 | |
dc.identifier | Dixon, William V.; Chayer, Pierre; Latour, Marilyn; Miller Bertolami, Marcelo Miguel; Benjamin, Robert A.; Observations of the ultraviolet-bright star Y453 in the globular cluster M4 (NGC 6121); IOP Publishing; Astronomical Journal; 154; 3; 9-2017 | |
dc.identifier | 0004-6256 | |
dc.identifier | http://hdl.handle.net/11336/42581 | |
dc.identifier | CONICET Digital | |
dc.identifier | CONICET | |
dc.identifier.uri | http://repositorioslatinoamericanos.uchile.cl/handle/2250/1865158 | |
dc.description.abstract | We present a spectral analysis of the UV-bright star Y453 in M4. Model fits to the star´s optical spectrum yield Teff ∼ 56,000 K. Fits to the star´s FUV spectrum, obtained with the Cosmic Origins Spectrograph on board the Hubble Space Telescope, reveal it to be considerably hotter, with Teff ∼ 72,000 K. We adopt Teff = 72,000 ± 2000 K and log g = 5.7 ± 0.2 as our best-fit parameters. Scaling the model spectrum to match the star´s optical and near-infrared magnitudes, we derive a mass M∗ = 0.53±0.24 M⊙ and luminosity = log L/L⊙ 2.84±0.05, consistent with the values expected of an evolved star in a globular cluster. Comparing the star with post-horizontal-branch evolutionary tracks, we conclude that it most likely evolved from the blue horizontal branch, departing the asymptotic giant branch before third dredge-up. It should thus exhibit the abundance pattern (O-poor and Na-rich) characteristic of the second-generation (SG) stars in M4. We derive the star´s photospheric abundances of He, C, N, O, Si, S, Ti, Cr, Fe, and Ni. CNO abundances are roughly 0.25 dex greater than those of the cluster´s SG stars, while the Si and S abundances match the cluster values. Abundances of the iron-peak elements (except for iron itself) are enhanced by 1-3 dex. Rather than revealing the star´s origin and evolution, this pattern reflects the combined effects of diffusive and mechanical processes in the stellar atmosphere. | |
dc.language | eng | |
dc.publisher | IOP Publishing | |
dc.relation | info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.3847/1538-3881/aa8450 | |
dc.relation | info:eu-repo/semantics/altIdentifier/url/http://iopscience.iop.org/article/10.3847/1538-3881/aa8450/meta | |
dc.rights | https://creativecommons.org/licenses/by-nc-sa/2.5/ar/ | |
dc.rights | info:eu-repo/semantics/openAccess | |
dc.subject | Abundances | |
dc.subject | Atmospheres | |
dc.subject | Ultraviolet | |
dc.subject | Stars | |
dc.subject | NGC 6121 (estrella) | |
dc.subject | Y453 (estrella) | |
dc.title | Observations of the ultraviolet-bright star Y453 in the globular cluster M4 (NGC 6121) | |
dc.type | Artículos de revistas | |
dc.type | Artículos de revistas | |
dc.type | Artículos de revistas | |