Mapping the Shores of the Brown Dwarf Desert. I. Upper Scorpius

By A. Kraus, Michael J. Ireland, F. Martinache, J. Lloyd. 2007

218 citations recorded by the source corpus.

We present the results of a survey for stellar and substellar companions to 82 young stars in the nearby OB association Upper Scorpius. This survey used nonredundant aperture mask interferometry to achieve typical contrast limits of Δ K ∼ 5–6 at the diffraction limit, revealing 12 new binary companions that lay below the detection limits of traditional high-resolution imaging; we also summarize a complementary snapshot imaging survey that discovered seven directly resolved companions. The overall frequency of binary companions (~35−4+5% at separations of 6-435 AU) appears to be equivalent to field stars of similar mass, but companions could be more common among lower mass stars than for the field. The companion mass function has statistically significant differences compared to several suggested mass functions for the field, and we suggest an alternate lognormal parameterization of the mass function. Our survey limits encompass the entire brown dwarf mass range, but we only detected a single companion that might be a brown dwarf; this deficit resembles the so-called brown dwarf desert that has been observed by radial velocity planet searches. Finally, our survey’s deep detection limits extend into the top of the planetary mass function, reaching 8-12 MJup for half of our sample. We have not identified any planetary companions at high confidence (≳99.5%), but we have identified four candidate companions at lower confidence (≳97.5%) that merit additional follow-up to confirm or disprove their existence.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/bbf322f1b5ac3f70872bdc3eb11054399a4eb494

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In Astronomy and Astrophysics

1. Michael C. Liu
2. A. Kraus
3. T. Dupuy
4. B. Bowler
5. A. Mann
6. Michael J. Ireland
7. E. Gaidos
8. D. Charbonneau

Citations in the corpus

• They are small worlds after all: revised properties of Kepler M dwarf stars and their planets (2015, methodology): “NRM data were analyzed following the method of Kraus et al. (2008) and Kraus et al. (2011).”
• THE PALOMAR/KECK ADAPTIVE OPTICS SURVEY OF YOUNG SOLAR ANALOGS: EVIDENCE FOR A UNIVERSAL COMPANION MASS FUNCTION (2008, methodology): “A similar log-normal CMF was inferred independently by Kraus et al. (2008) in their analysis of resolved binaries in Upper Scorpius.”
• THE ROLE OF MULTIPLICITY IN DISK EVOLUTION AND PLANET FORMATION (2011, background): “The high frequency of multiple star systems (e.g., Kraus et al. 2008, 2011) and the potentially dramatic dynamical effect of binary companions on disks mean that we must determine the relationship between disks and binary companions in order to fully understand disk evolution and planet formation.”
• MAPPING THE SHORES OF THE BROWN DWARF DESERT. II. MULTIPLE STAR FORMATION IN TAURUS–AURIGA (2011, methodology): “Most surveys of young stars in these regions (e.g., Ghez et al. 1993, Leinart et al. 1993; Simon et al. 1995; Kouwenhoven et al. 2007; Kraus et al. 2008) find a significantly higher binary frequency than in the field, such that the binary frequency of solar-type stars in Taurus might approach 100%.”
• Stellar Multiplicity (2013, methodology): “The latter conclusion also matches the results of Kouwenhoven et al. (2007b) for intermediate-mass multiple systems in Upper Scorpius.”
• LkCa 15: A YOUNG EXOPLANET CAUGHT AT FORMATION? (2011, methodology): “Data Analysis The data analysis up to the calibration step was identical to that used in previous papers (Ireland et al. 2008; Kraus et al. 2008).”
• Binary Companions of Evolved Stars in APOGEE DR14: Search Method and Catalog of ∼5000 Companions (2018, background): “For example, binary stars have mass ratios that span from ≈0.03 to 1 (e.g., Kraus et al. 2008), and have periods from days to millions of years (e.g., Raghavan et al. 2010).”
• ZODIACAL EXOPLANETS IN TIME (ZEIT). III. A SHORT-PERIOD PLANET ORBITING A PRE-MAIN-SEQUENCE STAR IN THE UPPER SCORPIUS OB ASSOCIATION (2016, background): “The appendix of Kraus et al. (2008) contains a full explanation of the data reduction and binary profilefitting for aperture masking data.”
• Imaging Extrasolar Giant Planets (2016, result): “Combining these results with those from Kraus et al. (2008) and their own shallow imaging survey, Lafrenière et al. (2014) find that the frequency of 5–40 MJup companions between 50–250 AU is <1.8% and between 250–1000AU is 4.0+3.0 −1.2% assuming hot-start evolutionary models.”
• THE IMPACT OF STELLAR MULTIPLICITY ON PLANETARY SYSTEMS. I. THE RUINOUS INFLUENCE OF CLOSE BINARY COMPANIONS (2016, methodology): “As we described in Kraus et al. (2008, 2011), aperture-masking observations can yield contrasts as deep as ΔK∼6 at λ/ D and ΔK∼4 at 1/3 λ/D with observations of ∼5–15 minutes, and we have used the technique to identify dozens of binary companions that fall inside the detection limits of traditional…”
• Dearth of short-period Neptunian exoplanets - a desert in period-mass and period-radius planes (2016, background): “In this sense, the Neptunian desert might be similar to the shortperiod brown-dwarf desert (e.g., Grether & Lineweaver 2006; Cheetham et al. 2015; Bouchy et al. 2015), in the range of ∼ 20–80MJup, which distinguishes between planets and stellar companions (e.g., Armitage & Bonnell 2002; Ma & Ge…”
• THE VLA NASCENT DISK AND MULTIPLICITY SURVEY OF PERSEUS PROTOSTARS (VANDAM). II. MULTIPLICITY OF PROTOSTARS IN THE PERSEUS MOLECULAR CLOUD (2016, background): “Multiplicity is becoming well-characterized for pre-main sequence stars (Class II and III sources) with radial velocity and high-contrast imaging techniques (e.g., Reipurth et al. 2007; Kraus et al. 2008, 2011; Kraus & Hillenbrand 2012).”
• GIANT PLANET MIGRATION, DISK EVOLUTION, AND THE ORIGIN OF TRANSITIONAL DISKS (2009, unknown): “…using high-resoluti n imaging have discovered significant numbers of close binaries even in regions that had previously been well studied (Ireland & Kraus 2008; Kraus et al. 2008), suggesting that the fraction of stars that exist as binaries with separations of∼ 3–30AU is not well constrained.”
• Inverse dynamical population synthesis: Constraining the initial conditions of young stellar clusters by studying their binary populations (2012, methodology): “Here we use the data of Kraus et al. (2008), who observe 82 systems finding 27 companion stars at separations of 6− 435 AU.”
• The Close Binary Fraction of Solar-type Stars Is Strongly Anticorrelated with Metallicity (2018, background): “…stars, i.e., slightly older Class II and III protostars, in various star-forming environments such as Taurus, Upper Scorpius, Ophiuchus, and Orion exhibit a factor of ≈2 binary excess across intermediate separations a≈10–100 au (Ghez et al. 1993; Kraus et al. 2008, 2011; Duchêne et al. 2018).”
• TWO WIDE PLANETARY-MASS COMPANIONS TO SOLAR-TYPE STARS IN UPPER SCORPIUS (2010, background): “The survey consists of a subset of the aperture-masking interferometry sample reported by Kraus et al. (2008).”
• Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839–0446358 (2008, methodology): “′′16 in separation (the lower limit corresponding to the diffraction limit of the aperture mask) using the Monte-Carlo approach described in Kraus et al. (2008).”