THE PALOMAR/KECK ADAPTIVE OPTICS SURVEY OF YOUNG SOLAR ANALOGS: EVIDENCE FOR A UNIVERSAL COMPANION MASS FUNCTION

By S. Metchev, L. Hillenbrand. 2008

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We present results from an adaptive optics survey for substellar and stellar companions to Sun-like stars. The survey targeted 266 F5–K5 stars in the 3 Myr–3 Gyr age range with distances of 10–190 pc. Results from the survey include the discovery of two brown dwarf companions (HD 49197B and HD 203030B), 24 new stellar binaries, and a triple system. We infer that the frequency of 0.012–0.072 M☉ brown dwarfs in 28–1590 AU orbits around young solar analogs is 3.2+3.1−2.7% (2σ limits). The result demonstrates that the deficiency of substellar companions at wide orbital separations from Sun-like stars is less pronounced than in the radial velocity “brown dwarf desert.” We infer that the mass distribution of companions in 28–1590 AU orbits around solar-mass stars follows a continuous dN/dM2 ∝ M−0.42 relation over the 0.01–1.0 M☉ secondary mass range. While this functional form is similar to that for isolated objects less than 0.1 M☉, over the entire 0.01–1.0 M☉ range, the mass functions of companions and of isolated objects differ significantly. Based on this conclusion and on similar results from other direct imaging and radial velocity companion surveys in the literature, we argue that the companion mass function follows the same universal form over the entire range between 0 and 1590 AU in orbital semimajor axis and ≈ 0.01–20 M☉ in companion mass. In this context, the relative dearth of substellar versus stellar secondaries at all orbital separations arises naturally from the inferred form of the companion mass function.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/abbf5e97df39ec72e2f98d8816a9a7c0d1ed3514

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Citations in the corpus

FROM BINARIES TO MULTIPLES. I. DATA ON F AND G DWARFS WITHIN 67 pc OF THE SUN (2014, background): “Only a small fraction of nearby dwarfs were targeted by AO in search of companions to exo-planet hosts (Eggenberger et al. 2007), to spectroscopic binaries (Tokovinin et al. 2006), or to young stars (Metchev & Hillenbrand 2009; Chauvin et al. 2010).”
THE RUNTS OF THE LITTER: WHY PLANETS FORMED THROUGH GRAVITATIONAL INSTABILITY CAN ONLY BE FAILED BINARY STARS (2009, background): “Note that the overall dearth of brown dwarf companions to solar mass stars is not a selection effect (Metchev & Hillenbrand 2009; Zuckerman & Song 2009).”
Imaging Extrasolar Giant Planets (2016, background): “The Palomar and Keck adaptive optics survey by Metchev & Hillenbrand (2009) is another especially valuable contribution; they imaged 266 FGK stars and discovered two brown dwarf companions, HD 49197 B (Metchev & Hillenbrand 2004) and HD 203030 B (Metchev & Hillenbrand 2006), implying a substellar…”
Stellar Multiplicity (2013, background): “In addition, we note that substellar companions to solar-type stars in open clusters are rare (Itoh et al. 2011, Metchev & Hillenbrand 2009), although a few have been recently discovered (Geißler et al. 2012, Rodriguez et al. 2012).”
Mapping the Shores of the Brown Dwarf Desert. I. Upper Scorpius (2007, background): “In contrast, imaging surveys targeting wider separations have found that the frequency of such companions may not be anomalously low, but rather an extension of the binary mass-ratio function to lower masses (Metchev & Hillenbrand 2009).”
Adaptive Optics for Astronomy (2012, background): “In the former case, AO has been cardinal in searches for low mass companions in the vicinity of higher mass stars, from an early survey of OB stars using ADONIS (Shatsky & Tokovinin 2002) to observations around solar analogues (Metchev & Hillenbrand 2009).”
LOW-MASS TERTIARY COMPANIONS TO SPECTROSCOPIC BINARIES. I. COMMON PROPER MOTION SURVEY FOR WIDE COMPANIONS USING 2MASS (2009, methodology): “However, when comparing the substellar tertiary rate of this sample, 3.8±2.2%, to that of similar surveys (McCarthy & Zuckerman 2004; Metchev & Hillenbrand 2009), 3.2%, we found little difference, though it should be noted that all cases deal with small-number statistics.”
TWO WIDE PLANETARY-MASS COMPANIONS TO SOLAR-TYPE STARS IN UPPER SCORPIUS (2010, background): “…sensitive to the presence of ULMCs, and a full treatment should consider all surveys that have properly reported null detections and detection limits (e.g. Sartoretti et al. 1998; Massarotti et al. 2005; Tanner et al. 2007; Lafrenière et al. 2008a; Metchev & Hillenbrand 2009; Chauvin et al. 2010).”
PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, background): “Metchev & Hillenbrand (2009) compared all published direct imaging searches for brown dwarf companions as of 2009 and found a tentative trend between the frequency of brown dwarf companions and both stellar host mass and separation.”
The M-dwarfs in Multiples (MinMs) survey – I. Stellar multiplicity among low-mass stars within 15 pc (2015, methodology): “Previous comparisons with automated detection procedures have verified the reliability of visual inspection (Metchev & Hillenbrand 2009), and we repeated the inspection multiple times for each target on both individual and combined frames.”
MAPPING THE SHORES OF THE BROWN DWARF DESERT. II. MULTIPLE STAR FORMATION IN TAURUS–AURIGA (2011, background): “This lower limit is similar to the completeness-corrected frequency of 3.2+3.1 −2.7% reported by Metchev & Hillenbrand (2009) for a slightly narrower range of separations (28–1590 AU) and companion masses (12–72 MJup).”
OBSERVATIONS OF HIERARCHICAL SOLAR-TYPE MULTIPLE STAR SYSTEMS (2015, background): “The object was already targeted by Metchev & Hillenbrand (2009) in their survey of young stars, but the binary was not detected.”
A SURVEY OF STELLAR FAMILIES: MULTIPLICITY OF SOLAR-TYPE STARS (2009, background): “…surveys (e.g., Marcy et al. 2004; Mayor et al. 2004; Butler et al. 2006) and high-contrast imaging efforts (e.g., Burgasser et al. 2003; Metchev & Hillenbrand 2009) since the prior studies yield observational results of substellar companions and enable us to better constrain our…”
THE GEMINI/NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF PLANETS AROUND YOUNG MOVING GROUP STARS (2013, methodology): “We also retrieved the substellar companions AB Pic B (Chauvin et al. 2005b) and HR 7329 B (Lowrance et al. 2000) as well as the known stellar companion to HD 82688 (Metchev & Hillenbrand 2009).”
PALM-3000: EXOPLANET ADAPTIVE OPTICS FOR THE 5 m HALE TELESCOPE (2013, background): “…performance and successful investigations of brown dwarf companions (Boccaletti et al. 2003; Lloyd et al. 2006; González-Garćıa et al. 2006; Metchev and Hillenbrand 2009), the ability of PALM-241 to directly image stellar companion exoplanets using the full 5.1-m aperture was limited to…”