White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] Ratio
We present results from our ongoing far-ultraviolet archival analysis of cataclysmic variable white dwarf (WD) abundances for six more systems: four SU UMa dwarf novae (BW Scl, SW UMa, BC UMa, and VW Hyi) together with the dwarf nova RX And, and the novalike DW UMa. To derive a reliable nitrogen abu...
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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/ad0546 |
| _version_ | 1797384804994383872 |
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| author | Patrick Godon Edward M. Sion |
| author_facet | Patrick Godon Edward M. Sion |
| author_sort | Patrick Godon |
| collection | DOAJ |
| description | We present results from our ongoing far-ultraviolet archival analysis of cataclysmic variable white dwarf (WD) abundances for six more systems: four SU UMa dwarf novae (BW Scl, SW UMa, BC UMa, and VW Hyi) together with the dwarf nova RX And, and the novalike DW UMa. To derive a reliable nitrogen abundance, for the four SU UMa systems (with a WD temperature T _wd ∼ 14,000 to ∼22,000 K), we use the dominant N i (1492 Å) absorption line; for DW UMa (with T _wd possibly as high as 60,000 K), we use the N v (∼1240 Å) doublet; and for RX And (with T _wd = 33,800 K), we use the N iii (1183.0 and 1184.6 Å) absorption lines. We find a [N/C] ratio of the order of 1–100 (in solar units). Oxygen, silicon, phosphorus are mostly underabundant while aluminum is mostly overabundant. We also derive magnesium, sulfur, calcium, and iron for a few systems. VW Hyi has a solar composition secondary implying the suprasolar [N/C] ratio very likely originates in the WD itself, e.g., accretion-driven dredge-up, mixing, and convection bringing material from deeper regions to the WD surface. If the donor star in the other five systems is nonevolved, the WD is the origin for the [N/C] ratio in these systems, either directly as in VW Hyi or due to contamination of the donor and accretion disk by the repetitive explosive CNO burning during the common envelope stage of the nova explosions. |
| first_indexed | 2024-03-08T21:44:03Z |
| format | Article |
| id | doaj.art-590e340088ec4063a9f6462d13cb7d68 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-08T21:44:03Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-590e340088ec4063a9f6462d13cb7d682023-12-20T10:32:54ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0196013710.3847/1538-4357/ad0546White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] RatioPatrick Godon0https://orcid.org/0000-0002-4806-5319Edward M. Sion1https://orcid.org/0000-0003-4440-0551Villanova University , 800 E. Lancaster Ave., Villanova, PA 19085, USA ; patrick.godon@villanova.edu; Johns Hopkins University , 3400 N. Charles St., Baltimore, MD 21218, USAVillanova University , 800 E. Lancaster Ave., Villanova, PA 19085, USA ; patrick.godon@villanova.eduWe present results from our ongoing far-ultraviolet archival analysis of cataclysmic variable white dwarf (WD) abundances for six more systems: four SU UMa dwarf novae (BW Scl, SW UMa, BC UMa, and VW Hyi) together with the dwarf nova RX And, and the novalike DW UMa. To derive a reliable nitrogen abundance, for the four SU UMa systems (with a WD temperature T _wd ∼ 14,000 to ∼22,000 K), we use the dominant N i (1492 Å) absorption line; for DW UMa (with T _wd possibly as high as 60,000 K), we use the N v (∼1240 Å) doublet; and for RX And (with T _wd = 33,800 K), we use the N iii (1183.0 and 1184.6 Å) absorption lines. We find a [N/C] ratio of the order of 1–100 (in solar units). Oxygen, silicon, phosphorus are mostly underabundant while aluminum is mostly overabundant. We also derive magnesium, sulfur, calcium, and iron for a few systems. VW Hyi has a solar composition secondary implying the suprasolar [N/C] ratio very likely originates in the WD itself, e.g., accretion-driven dredge-up, mixing, and convection bringing material from deeper regions to the WD surface. If the donor star in the other five systems is nonevolved, the WD is the origin for the [N/C] ratio in these systems, either directly as in VW Hyi or due to contamination of the donor and accretion disk by the repetitive explosive CNO burning during the common envelope stage of the nova explosions.https://doi.org/10.3847/1538-4357/ad0546White dwarf starsDwarf novaeNova-like variable starsCataclysmic variable starsSU Ursae Majoris stars |
| spellingShingle | Patrick Godon Edward M. Sion White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] Ratio The Astrophysical Journal White dwarf stars Dwarf novae Nova-like variable stars Cataclysmic variable stars SU Ursae Majoris stars |
| title | White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] Ratio |
| title_full | White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] Ratio |
| title_fullStr | White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] Ratio |
| title_full_unstemmed | White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] Ratio |
| title_short | White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] Ratio |
| title_sort | white dwarf photospheric abundances in cataclysmic variables iv deriving the n c ratio |
| topic | White dwarf stars Dwarf novae Nova-like variable stars Cataclysmic variable stars SU Ursae Majoris stars |
| url | https://doi.org/10.3847/1538-4357/ad0546 |
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