J/ApJ/923/100 SOAR spectrum of V5558 Sgr (NOVA Sgr 2007) (Metzger+, 2021)
Transients from the cataclysmic deaths of cataclysmic variables.
Metzger B.D., Zenati Y., Chomiuk L., Shen K.J., Strader J.
<Astrophys. J., 923, 100-100 (2021)>
=2021ApJ...923..100M 2021ApJ...923..100M (SIMBAD/NED BibCode)
ADC_Keywords: Novae; Spectra, optical
Keywords: Cataclysmic variable stars; Stellar mergers; Classical novae
Stellar accretion disks; Bipolar nebulae
Abstract:
We explore the observational appearance of the merger of a low-mass
star with a white dwarf (WD) binary companion. We are motivated by
recent work finding that multiple tensions between the observed
properties of cataclysmic variables (CVs) and standard evolution
models are resolved if a large fraction of CV binaries merge as a
result of unstable mass transfer. Tidal disruption of the secondary
forms a geometrically thick disk around the WD, which subsequently
accretes at highly super-Eddington rates. Analytic estimates and
numerical hydrodynamical simulations reveal that outflows from the
accretion flow unbind a large fraction ≳90% of the secondary at
velocities ∼500-1000km/s within days of the merger. Hydrogen
recombination in the expanding ejecta powers optical transient
emission lasting about a month with a luminosity ≳1038erg/s,
similar to slow classical novae and luminous red novae from ordinary
stellar mergers. Over longer timescales the mass accreted by the WD
undergoes hydrogen shell burning, inflating the remnant into a giant
of luminosity ∼300-5000L☉, effective temperature Teff∼3000K,
and lifetime ∼104-105yr. We predict that ∼103-104 Milky Way
giants are CV merger products, potentially distinguishable by atypical
surface abundances. We explore whether any Galactic historical slow
classical novae are masquerading CV mergers by identifying four such
post-nova systems with potential giant counterparts for which a CV
merger origin cannot be ruled out. We address whether the historical
transient CK Vul and its gaseous/dusty nebula resulted from a CV
merger.
Description:
We obtained a spectrum of V5558 Sgr on 2021 July 6.1 using the Goodman
High Throughput Spectrograph on the 4.1m Southern Astrophysical
Research (SOAR) telescope, making use of the 400line/mm grating and
covering 4000-7910Å. See Appendix C.6.
Objects:
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RA (ICRS) DE Designation(s)
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18 10 18.26 -18 46 52.2 V5558 Sgr = NOVA Sgr 2007
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig7.dat 54 1977 The 4.1m Southern Astrophysical Research (SOAR)
telescope spectrum of V5558 Sgr
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See also:
B/cb : Cataclysmic Binaries, LMXBs, and related objects (Ritter+, 2004)
V/110 : Catalog of Cataclysmic Variables (Downes+ 2001)
V/123 : Catalog of Cataclysmic Variables (Downes+ 2001-2006)
J/A+A/513/L7 : Post common envelope bin. from SDSS. VIII (Schreiber+, 2010)
J/ApJ/723/1072 : The ELM survey. I. Low-mass white dwarfs (Brown+, 2010)
J/ApJ/730/67 : Radial velocities of low-mass white dwarfs (Brown+, 2011)
J/ApJS/194/28 : The evolution of cataclysmic variables (Knigge+, 2011)
J/ApJS/197/31 : Swift X-ray obs. of classical novae. II. (Schwarz+, 2011)
J/ApJ/788/164 : Known Galactic classical novae (Pagnotta+, 2014)
J/ApJ/834/196 : Galactic novae with m≤10 from 1900 to 2015 (Shafter, 2017)
J/other/NatAs/2.778 : Hyperfine rot. transitions of 26Al19F (Kaminski+ 2018)
J/A+A/630/A75 : Six luminous red novae photometry (Pastorello+, 2019)
J/ApJ/910/134 : Swift-XRT light curves of 13 Galactic novae (Gordon+, 2021)
J/A+A/653/A134 : AT 2018bwo light curves (Blagorodnova+, 2021)
Byte-by-byte Description of file: fig7.dat
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Bytes Format Units Label Explanations
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1- 10 E10.4 0.1nm lambda [3999.7/7911.8] Wavelength; Angstroms
12- 21 E10.4 cW/m/nm Flux [1.5e-15/1.8e-14] Reduced flux (1)
23- 32 E10.4 cW/m/nm Raw [1.5e-15/1.8e-14] Raw flux (1)
34- 43 E10.4 cW/m/nm Bkgrd [1.8e-16/1.2e-15] Background flux (1)
45- 54 E10.4 cW/m/nm e_Flux [1.5e-17/7.4e-17] Uncertainty in Flux (1)
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Note (1): In units of erg/s/cm2/Angstroms.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-May-2023