Infrared Spectroscopy of the Secondary Star in ST Leonis Minoris: Implications for Evolution and High‐/Low‐State Behavior in Cataclysmic Variables

Howell, Steve B.; Ciardi, David R.; Dhillon, V. S.; Skidmore, Warren

doi:10.1086/308382

Cited by 40 publications

(48 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Again, we stress the fact that we measured the M5.5±0.5 spectral type of the secondary star in HS 0220+0603 from the average of spectra taken at orbital phases around its inferior conjunction, so any information on spectral type change along the orbit is lost. An illustrative example is the case of the polar CV ST LMi, whose secondary star shows a changing temperature with a much cooler region at orbital phase 0.8 (Howell et al 2000). Therefore, more detailed studies of the secondary stars in the nova-like variables which populate the 3-4 h orbital period range during low states should be conducted in order to check how frequent these secondary stars are.…”

Section: The M-type Companionmentioning

confidence: 99%

“…Livio & Pringle (1994) and King & Cannizzo (1998) proposed an accumulation of large starspots close to the inner Lagrangian point (L1) as a way of inhibiting Roche-lobe overflow, but Howell et al (2000) put the case of the polar ST LMi forward to challenge this scenario and proposed that it is changes in the level of magnetic activity of the secondary star that may be behind the observed high-/low-state transitions. This idea had been already explored by Bianchini (1992), who invoked solar-like magnetic cycles with time scales of about a decade.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamical masses of a nova-like variable on the edge of the period gap

Rodríguez‐Gil

Shahbaz

Marsh

et al. 2015

Mon. Not. R. Astron. Soc.

Self Cite

View full text Add to dashboard Cite

We present the first dynamical determination of the binary parameters of an eclipsing SW Sextantis star in the 3-4 hour orbital period range during a low state. We obtained time-resolved optical spectroscopy and photometry of HS 0220+0603 during its 2004-2005 low brightness state, as revealed in the combined SMARTS, IAC80 and M1 Group long-term optical light curve.The optical spectra taken during primary eclipse reveal a secondary star spectral type of M5.5±0.5 as derived from molecular band-head indices. The spectra also provide the first detection of a DAB white dwarf in a cataclysmic variable. By modelling its optical spectrum we estimate a white dwarf temperature of 30 000 ± 5 000 K.By combining the results of modelling the white dwarf eclipse from ULTRA-CAM light curves with those obtained by simultaneously fitting the emission-and absorption-line radial velocity curves and I-band ellipsoidal light curves, we measure the stellar masses to be M 1 = 0.87 ± 0.09 M and M 2 = 0.47 ± 0.05 M for the white dwarf and the M dwarf, respectively, and an inclination of the orbital plane of i ≈ 79 o . A radius of 0.0103 ± 0.0007 R is obtained for the white dwarf. The secondary star in HS 0220+0603 is likely too cool and undersized for its mass.

show abstract

Section: The M-type Companionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamical masses of a nova-like variable on the edge of the period gap

Rodríguez‐Gil

Shahbaz

Marsh

et al. 2015

Mon. Not. R. Astron. Soc.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Phase-resolved K-band spectroscopy of a polar in a low state has been presented only once before, for the star ST LMi (Howell et al 2000). These authors discovered a localized cooler region on the secondary star and concluded that the most likely cause was starspots.…”

Section: Am Her In the Irmentioning

confidence: 99%

A Multiwavelength Study of AM Herculis during the 2002-2004 Low States

Kafka

Honeycutt

Howell

et al. 2005

View full text Add to dashboard Cite

We present two epochs of low-state, near-IR spectroscopy of the polar prototype AM Her, along with K-band spectroscopy and JHK photometry. Combining our data with long-term (RoboScope) photometry of the system, we determine a new spectroscopic ephemeris for AM Her. According to the new ephemeris, the primary photometric minimum of the high-state light curve of the system is centered at phase zero. Our K-band spectrum, in which the Br and He i (2.06 m) lines are essentially absent, confirms that during the low state, accretion was negligible. Ellipsoidal variations dominate the J-band light curve, whereas cyclotron harmonics are prominent in the H-and K-band light curves. Cyclotron emission during a time of negligible accretion has been observed in other low-Ṁ polars. The H line is often triple peaked, and all three components follow the motion of the secondary star. The central peak likely originates from the irradiated inner hemisphere of the secondary. The blue/red satellite components reach velocities of $300 km s À1 with respect to the secondary and coincide in phase with flaring events recently discovered from a photometric campaign. We argue that the satellite behavior is consistent with motions in large loop coronal structures on the secondary star.

show abstract

“…ST LMi (=CW 1103+254) is a short-period polar (P orb ¼ 114 minutes) containing a 0.7 M primary (Ramsay et al 2004) with a likely temperature of 11,000 K (Araujo- Betancor et al 2005;Sion 1999) and a M5-M6 secondary ( Knigge 2006;Harrison et al 2005;Howell et al 2000;Warner 1995) at a distance of 115-138 pc (Araujo-Betancor et al 2005;Kafka et al 2007). It was classified as an AM Her object by Stockman et al (1983) on the basis of its highly variable polarization.…”

Section: Introductionmentioning

confidence: 99%

Cyclotron Modeling Phase‐Resolved Infrared Spectroscopy of Polars. III. AM Herculis and ST Leo Minoris

Campbell

Harrison

Kafka

2008

Astrophysical Journal

View full text Add to dashboard Cite

We present phase-resolved low-resolution infrared spectra of AM Her and ST LMi, two low-field polars that we observed with SPEX on the IRTF. Optical /NIR light curves are also published to help constrain the viewing geometry and brightness of the objects at the time they were observed. Currently, only limited IR spectra have been published for these objects, and none with the phase-coverage presented here. In both cases, the resulting spectra are dominated by emission from the secondary star in the NIR. However, the emission regions are also self-eclipsed, allowing us to isolate the cyclotron emission through subtraction of the dim-phase spectrum. We use a constant-lambda prescription to model the changing cyclotron features seen in the resulting data. For AM Her, we find a best-fit model of B ¼ 13:6 MG, kT ¼ 4:0 keV, and log Ã ¼ 5:0. The cyclotron derived accretion geometry is consistent with i ¼ 50 and ¼ 85 . For ST LMi, B ¼ 12:1 MG, kT ¼ 3:3 keV, and log Ã ¼ 5:7, with i ¼ 55 and ¼ 128 .

show abstract

Infrared Spectroscopy of the Secondary Star in ST Leonis Minoris: Implications for Evolution and High‐/Low‐State Behavior in Cataclysmic Variables

Cited by 40 publications

References 28 publications

Dynamical masses of a nova-like variable on the edge of the period gap

Dynamical masses of a nova-like variable on the edge of the period gap

A Multiwavelength Study of AM Herculis during the 2002-2004 Low States

Cyclotron Modeling Phase‐Resolved Infrared Spectroscopy of Polars. III. AM Herculis and ST Leo Minoris

Contact Info

Product

Resources

About