Sirius B Imaged in the Mid-Infrared: No Evidence for a Remnant Planetary System

Skemer, Andrew J.; Close, Laird M.

doi:10.1088/0004-637x/730/1/53

Cited by 39 publications

(16 citation statements)

References 24 publications

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“…The work most similar to our analysis here is the detection of Sirius B at 10µm by Skemer & Close (2011), in fact, it was part of our motivation for the present study. Skemer & Close (2011) used the well known orbit of the white dwarf companion to Sirius to de-orbit 4 years worth of images.…”

Section: Related Worksupporting

confidence: 58%

Direct Imaging in the Habitable Zone and the Problem of Orbital Motion

Males

Skemer

2013

ApJ

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High contrast imaging searches for exoplanets have been conducted on 2.4-10 m telescopes, typically at H band (1.6µm) and used exposure times of ∼ 1hr to search for planets with semimajor axes of 10 AU. We are beginning to plan for surveys using extreme-AO systems on the next generation of 30-meter class telescopes, where we hope to begin probing the habitable zones (HZs) of nearby stars. Here we highlight a heretofore ignorable problem in direct imaging: planets orbit their stars. Under the parameters of current surveys, orbital motion is negligible over the duration of a typical observation. However, this motion is not negligible when using large diameter telescopes to observe at relatively close stellar distances (1-10pc), over the long exposure times (10-20 hrs) necessary for direct detection of older planets in the HZ. We show that this motion will limit our achievable signal-to-noise ratio and degrade observational completeness. Even on current 8m class telescopes, orbital motion will need to be accounted for in an attempt to detect HZ planets around the nearest sun-like stars α Cen A&B, a binary system now known to harbor at least one planet. Here we derive some basic tools for analyzing this problem, and ultimately show that the prospects are good for de-orbiting a series of shorter exposures to correct for orbital motion. * This result is equivalent to defining the gravitational constant in the focal plane as G = (0.0834D/(λd)) 2 and using the equation for speed in a circular orbit v circ = GM * a .

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Section: Related Worksupporting

confidence: 58%

Direct Imaging in the Habitable Zone and the Problem of Orbital Motion

Males

Skemer

2013

ApJ

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“…Remarkably, aside from the HST observations reported here, astrometry of SiriusB has been almost entirely neglected by professional astronomers for more than the past three decades, subsequent to a final 1986 photographic observation reported by Jasinta & Hidayat (1999). The only exception of which we are aware is a single measurement in 2005 derived from MIR observations with the Gemini South telescope (Skemer & Close 2011). Ten measurements by two amateur astronomers based on CCD frames obtained with small telescopes between 2008 and 2016 have been reported, their most recent publications being Anton (2014) and Daley (2016).…”

Section: Discussionmentioning

confidence: 81%

The Sirius System and Its Astrophysical Puzzles: Hubble Space Telescope and Ground-based Astrometry^∗

Bond

Schaefer

Gilliland

et al. 2017

ApJ

286

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Sirius, the seventh-nearest stellar system, is a visual binary containing the metallic-line A1V star SiriusA, the brightest star in the sky, orbited in a 50.13year period by SiriusB, the brightest and nearest white dwarf (WD). Using images obtained over nearly two decades with the Hubble Space Telescope (HST), along with photographic observations covering almost 20 years and nearly 2300 historical measurements dating back to the 19th century, we determine precise orbital elements for the visual binary. Combined with the parallax and the motion of the A component, these elements yield dynamical masses of M 2.063 0.023   and M 1.018 0.011   for SiriusA and B, respectively. Our precise HST astrometry rules out third bodies orbiting either star in the system, down to masses of ∼15-M 25 Jup . The location of SiriusB in the Hertzsprung-Russell diagram is in excellent agreement with theoretical cooling tracks for WDs of its dynamical mass, and implies a cooling age of ∼126Myr. The position of SiriusB on the mass-radius plane is also consistent with WD theory, assuming a carbon-oxygen core. Including the pre-WD evolutionary timescale of the assumed progenitor, the total age of SiriusB is about 228±10Myr. We calculated evolutionary tracks for stars with the dynamical mass of SiriusA, using two independent codes. We find it necessary to assume a slightly subsolar metallicity, of about Z 0.85  , to fit its location on the luminosity-radius plane. The age of SiriusA based on these models is about 237-247Myr, with uncertainties of±15Myr, consistent with that of the WD companion. We discuss astrophysical puzzles presented by the Sirius system, including the probability that the two stars must have interacted in the past, even though there is no direct evidence for this and the orbital eccentricity remains high.

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“…We use the unsaturated PSF of Sirius B in the Br α images for photometric calibration. Although no prior Br α photometry of Sirius B exists, its overall brightness in the near-to mid-infrared can be predicted by a 25,193 ± 37 K blackbody (Barstow et al 2005;Skemer & Close 2011). Model spectra by Lejeune et al (1997) for a range of log g values up to 5 cm s −2 for T eff = 25,000 K indicate that while absorption lines are present in the mid-infrared, they exhibit rather small equivalent width.…”

Section: Subaru Ircs Br α Datamentioning

confidence: 94%

Piercing the Glare: A Direct Imaging Search for Planets in the Sirius System

Thalmann¹,

Usuda²,

Kenworthy³

et al. 2011

ApJ

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Astrometric monitoring of the Sirius binary system over the past century has yielded several predictions for an unseen third system component, the most recent one suggesting a 50 M Jup object in a ∼6.3 year orbit around Sirius A. Here we present two epochs of high-contrast imaging observations performed with Subaru IRCS and AO188 in the 4.05 μm narrowband Br α filter. These data surpass previous observations by an order of magnitude in detectable companion mass, allowing us to probe the relevant separation range down to the planetary-mass regime (6-12 M Jup at 1 , 2-4 M Jup at 2 , and 1.6 M Jup beyond 4). We complement these data with one epoch of M-band observations from MMT/AO Clio, which reach comparable performance. No data set reveals any companion candidates above the 5σ level, allowing us to refute the existence of Sirius C as suggested by the previous astrometric analysis. Furthermore, our Br α photometry of Sirius B confirms the lack of an infrared excess beyond the white dwarf's blackbody spectrum.

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Sirius B Imaged in the Mid-Infrared: No Evidence for a Remnant Planetary System

Cited by 39 publications

References 24 publications

Direct Imaging in the Habitable Zone and the Problem of Orbital Motion

Direct Imaging in the Habitable Zone and the Problem of Orbital Motion

The Sirius System and Its Astrophysical Puzzles: Hubble Space Telescope and Ground-based Astrometry^∗

Piercing the Glare: A Direct Imaging Search for Planets in the Sirius System

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Sirius B Imaged in the Mid-Infrared: No Evidence for a Remnant Planetary System

Cited by 39 publications

References 24 publications

Direct Imaging in the Habitable Zone and the Problem of Orbital Motion

Direct Imaging in the Habitable Zone and the Problem of Orbital Motion

The Sirius System and Its Astrophysical Puzzles: Hubble Space Telescope and Ground-based Astrometry∗

Piercing the Glare: A Direct Imaging Search for Planets in the Sirius System

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Product

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The Sirius System and Its Astrophysical Puzzles: Hubble Space Telescope and Ground-based Astrometry^∗