The Carbon Star DY Persei May Be a Cool R Coronae Borealis Variable
Optical and near-IR photometry suggests that the carbon star DY Persei exhibits fadings similar to those of R Coronae Borealis (RCB) variables. Photometric surveys of the Galaxy and Magellanic Clouds uncovered new DY Per variables with infrared photometry identifying them with cool carbon stars, per...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acc574 |
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| author | D. A. García-Hernández N. Kameswara Rao David L. Lambert K. Eriksson A. B. S. Reddy Thomas Masseron |
| author_facet | D. A. García-Hernández N. Kameswara Rao David L. Lambert K. Eriksson A. B. S. Reddy Thomas Masseron |
| author_sort | D. A. García-Hernández |
| collection | DOAJ |
| description | Optical and near-IR photometry suggests that the carbon star DY Persei exhibits fadings similar to those of R Coronae Borealis (RCB) variables. Photometric surveys of the Galaxy and Magellanic Clouds uncovered new DY Per variables with infrared photometry identifying them with cool carbon stars, perhaps, with an unusual tendency to shed mass. In an attempt to resolve DY Per’s identity crisis—a cool carbon giant or a cool RCB variable?—we analyze a high-resolution IGRINS H &K-band spectrum of DY Per. The CO first-overtone bands in the K band of DY Per show a high abundance of ^18 O such that ^16 O/ ^18 O = 4 ± 1, a ratio sharply at odds with published results for regular cool carbon giants with ^16 O/ ^18 O ∼ 1000 but this exceptionally low ratio is characteristic of RCB variables and HdC stars. This similarity suggests that DY Per indeed may be a cool RCB variable. Current opinion considers RCB variables to result from the merger of a He onto a CO white dwarf; observed abundances of these H-deficient stars including the exceptionally low ^16 O/ ^18 O ratios are in fair accord with predicted compositions for white dwarf merger products. An H-deficiency for DY Per is not directly observable but is suggested from the strength of an HF line and an assumption that F may be overabundant, as observed and predicted for RCB stars. |
| first_indexed | 2024-03-12T04:08:39Z |
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| id | doaj.art-21efa1982df04490a6322c0ecde86a67 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:08:39Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-21efa1982df04490a6322c0ecde86a672023-09-03T11:09:50ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0194811510.3847/1538-4357/acc574The Carbon Star DY Persei May Be a Cool R Coronae Borealis VariableD. A. García-Hernández0https://orcid.org/0000-0002-1693-2721N. Kameswara Rao1David L. Lambert2https://orcid.org/0000-0003-1814-3379K. Eriksson3A. B. S. Reddy4Thomas Masseron5https://orcid.org/0000-0002-6939-0831Instituto de Astrofísica de Canarias , C/ Via Láctea s/n, E-38205 La Laguna, Spain ; agarcia@iac.es; Departamento de Astrofísica, Universidad de La Laguna (ULL) , E-38206 La Laguna, SpainIndian Institute of Astrophysics , Bangalore 560034, IndiaThe W.J. McDonald Observatory & Department of Astronomy, University of Texas at Austin , Austin, TX 78712, USATheoretical Astrophysics, Department of Physics and Astronomy, Uppsala University , Box 516, SE-751 20, Uppsala, SwedenIndian Institute of Astrophysics , Bangalore 560034, IndiaInstituto de Astrofísica de Canarias , C/ Via Láctea s/n, E-38205 La Laguna, Spain ; agarcia@iac.es; Departamento de Astrofísica, Universidad de La Laguna (ULL) , E-38206 La Laguna, SpainOptical and near-IR photometry suggests that the carbon star DY Persei exhibits fadings similar to those of R Coronae Borealis (RCB) variables. Photometric surveys of the Galaxy and Magellanic Clouds uncovered new DY Per variables with infrared photometry identifying them with cool carbon stars, perhaps, with an unusual tendency to shed mass. In an attempt to resolve DY Per’s identity crisis—a cool carbon giant or a cool RCB variable?—we analyze a high-resolution IGRINS H &K-band spectrum of DY Per. The CO first-overtone bands in the K band of DY Per show a high abundance of ^18 O such that ^16 O/ ^18 O = 4 ± 1, a ratio sharply at odds with published results for regular cool carbon giants with ^16 O/ ^18 O ∼ 1000 but this exceptionally low ratio is characteristic of RCB variables and HdC stars. This similarity suggests that DY Per indeed may be a cool RCB variable. Current opinion considers RCB variables to result from the merger of a He onto a CO white dwarf; observed abundances of these H-deficient stars including the exceptionally low ^16 O/ ^18 O ratios are in fair accord with predicted compositions for white dwarf merger products. An H-deficiency for DY Per is not directly observable but is suggested from the strength of an HF line and an assumption that F may be overabundant, as observed and predicted for RCB stars.https://doi.org/10.3847/1538-4357/acc574Chemically peculiar starsR Coronae Borealis variable starsChemical abundancesStellar atmospheresLate-type starsStellar evolution |
| spellingShingle | D. A. García-Hernández N. Kameswara Rao David L. Lambert K. Eriksson A. B. S. Reddy Thomas Masseron The Carbon Star DY Persei May Be a Cool R Coronae Borealis Variable The Astrophysical Journal Chemically peculiar stars R Coronae Borealis variable stars Chemical abundances Stellar atmospheres Late-type stars Stellar evolution |
| title | The Carbon Star DY Persei May Be a Cool R Coronae Borealis Variable |
| title_full | The Carbon Star DY Persei May Be a Cool R Coronae Borealis Variable |
| title_fullStr | The Carbon Star DY Persei May Be a Cool R Coronae Borealis Variable |
| title_full_unstemmed | The Carbon Star DY Persei May Be a Cool R Coronae Borealis Variable |
| title_short | The Carbon Star DY Persei May Be a Cool R Coronae Borealis Variable |
| title_sort | carbon star dy persei may be a cool r coronae borealis variable |
| topic | Chemically peculiar stars R Coronae Borealis variable stars Chemical abundances Stellar atmospheres Late-type stars Stellar evolution |
| url | https://doi.org/10.3847/1538-4357/acc574 |
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