The wide brown dwarf binary Oph 1622-2405 and discovery of a wide, low-mass binary in ophiuchus (Oph 1623-2402): A new class of young evaporating wide binaries?

Laird M Close, B. Zuckerman, Inseok Song, Travis S Barman, Christian Marois, Emily L. Rice, Nick Siegler, Bruce Macintosh, E. E. Becklin, Randy Campbell, James E. Lyke, Al Conrad, David Le Mignant

Research output: Contribution to journalArticle

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Abstract

We imaged five objects near the star-forming clouds of Ophiuchus with the Keck Laser Guide Star AO system. We resolved sources 11 (Oph 16222-2405) and 16 (Oph 16233-2402) from Allers and coworkers into binary systems. Source 11 is resolved into a 243 AU binary, the widest known for a very low mass (VLM) binary. The binary nature of source 11 was discovered first by Allers and independently here, during which we obtained the first spatially resolved R ∼ 2000 near-infrared (J and K) spectra, mid-IR photometry, and orbital motion estimates. We estimate for 11A and 11B gravities (log g > 3.75), ages (5 ± 2 Myr), luminosities [log(L/L) = -2.77 ± 0.10 and -2.96 ± 0.10], and temperatures (Teff = 2375 ± 175 K and 2175 ± 175 K). We find self-consistent DUSTY evolutionary model (Chabrier and coworkers) masses of 17-5+4 M J and 14-5+6 MJ, for 11A and 11B, respectively. Our masses are higher than those previously reported (13-15 M J and 7-8 MJ) by Jayawardhana & Ivanov. Hence, we find that the system is unlikely a "planetary mass binary," as do Luhman and coworkers, but it has the second lowest mass and lowest binding energy of any known binary. Oph 11 and Oph 16 belong to a newly recognized population of wide (≳100 AU), young (<10 Myr), roughly equal mass, VLM stellar and brown dwarf binaries. We deduce that ∼6% ± 3% of young (<10 Myr) VLM objects are in such wide systems. However, only 0.3% ± 0.1% of old field VLM objects are found in such wide systems. Thus, young, wide, VLM binary populations may be evaporating, due to stellar encounters in their natal clusters, leading to a field population depleted in wide VLM systems.

Original languageEnglish (US)
Pages (from-to)1492-1506
Number of pages15
JournalAstrophysical Journal
Volume660
Issue number2 I
DOIs
StatePublished - May 10 2007

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young
planetary mass
laser guide stars
old field
estimates
encounters
photometry
binding energy
near infrared
luminosity
gravitation
laser
orbits
stars
gravity
energy
temperature

Keywords

  • Binaries: general
  • Instrumentation: adaptive optics
  • Stars: evolution
  • Stars: formation
  • Stars: individual (2MASS J16222521-2405139, 2MASS J16233609-2402209)
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

The wide brown dwarf binary Oph 1622-2405 and discovery of a wide, low-mass binary in ophiuchus (Oph 1623-2402) : A new class of young evaporating wide binaries? / Close, Laird M; Zuckerman, B.; Song, Inseok; Barman, Travis S; Marois, Christian; Rice, Emily L.; Siegler, Nick; Macintosh, Bruce; Becklin, E. E.; Campbell, Randy; Lyke, James E.; Conrad, Al; Le Mignant, David.

In: Astrophysical Journal, Vol. 660, No. 2 I, 10.05.2007, p. 1492-1506.

Research output: Contribution to journalArticle

Close, LM, Zuckerman, B, Song, I, Barman, TS, Marois, C, Rice, EL, Siegler, N, Macintosh, B, Becklin, EE, Campbell, R, Lyke, JE, Conrad, A & Le Mignant, D 2007, 'The wide brown dwarf binary Oph 1622-2405 and discovery of a wide, low-mass binary in ophiuchus (Oph 1623-2402): A new class of young evaporating wide binaries?', Astrophysical Journal, vol. 660, no. 2 I, pp. 1492-1506. https://doi.org/10.1086/513417
Close, Laird M ; Zuckerman, B. ; Song, Inseok ; Barman, Travis S ; Marois, Christian ; Rice, Emily L. ; Siegler, Nick ; Macintosh, Bruce ; Becklin, E. E. ; Campbell, Randy ; Lyke, James E. ; Conrad, Al ; Le Mignant, David. / The wide brown dwarf binary Oph 1622-2405 and discovery of a wide, low-mass binary in ophiuchus (Oph 1623-2402) : A new class of young evaporating wide binaries?. In: Astrophysical Journal. 2007 ; Vol. 660, No. 2 I. pp. 1492-1506.
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abstract = "We imaged five objects near the star-forming clouds of Ophiuchus with the Keck Laser Guide Star AO system. We resolved sources 11 (Oph 16222-2405) and 16 (Oph 16233-2402) from Allers and coworkers into binary systems. Source 11 is resolved into a 243 AU binary, the widest known for a very low mass (VLM) binary. The binary nature of source 11 was discovered first by Allers and independently here, during which we obtained the first spatially resolved R ∼ 2000 near-infrared (J and K) spectra, mid-IR photometry, and orbital motion estimates. We estimate for 11A and 11B gravities (log g > 3.75), ages (5 ± 2 Myr), luminosities [log(L/L⊙) = -2.77 ± 0.10 and -2.96 ± 0.10], and temperatures (Teff = 2375 ± 175 K and 2175 ± 175 K). We find self-consistent DUSTY evolutionary model (Chabrier and coworkers) masses of 17-5+4 M J and 14-5+6 MJ, for 11A and 11B, respectively. Our masses are higher than those previously reported (13-15 M J and 7-8 MJ) by Jayawardhana & Ivanov. Hence, we find that the system is unlikely a {"}planetary mass binary,{"} as do Luhman and coworkers, but it has the second lowest mass and lowest binding energy of any known binary. Oph 11 and Oph 16 belong to a newly recognized population of wide (≳100 AU), young (<10 Myr), roughly equal mass, VLM stellar and brown dwarf binaries. We deduce that ∼6{\%} ± 3{\%} of young (<10 Myr) VLM objects are in such wide systems. However, only 0.3{\%} ± 0.1{\%} of old field VLM objects are found in such wide systems. Thus, young, wide, VLM binary populations may be evaporating, due to stellar encounters in their natal clusters, leading to a field population depleted in wide VLM systems.",
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AU - Zuckerman, B.

AU - Song, Inseok

AU - Barman, Travis S

AU - Marois, Christian

AU - Rice, Emily L.

AU - Siegler, Nick

AU - Macintosh, Bruce

AU - Becklin, E. E.

AU - Campbell, Randy

AU - Lyke, James E.

AU - Conrad, Al

AU - Le Mignant, David

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N2 - We imaged five objects near the star-forming clouds of Ophiuchus with the Keck Laser Guide Star AO system. We resolved sources 11 (Oph 16222-2405) and 16 (Oph 16233-2402) from Allers and coworkers into binary systems. Source 11 is resolved into a 243 AU binary, the widest known for a very low mass (VLM) binary. The binary nature of source 11 was discovered first by Allers and independently here, during which we obtained the first spatially resolved R ∼ 2000 near-infrared (J and K) spectra, mid-IR photometry, and orbital motion estimates. We estimate for 11A and 11B gravities (log g > 3.75), ages (5 ± 2 Myr), luminosities [log(L/L⊙) = -2.77 ± 0.10 and -2.96 ± 0.10], and temperatures (Teff = 2375 ± 175 K and 2175 ± 175 K). We find self-consistent DUSTY evolutionary model (Chabrier and coworkers) masses of 17-5+4 M J and 14-5+6 MJ, for 11A and 11B, respectively. Our masses are higher than those previously reported (13-15 M J and 7-8 MJ) by Jayawardhana & Ivanov. Hence, we find that the system is unlikely a "planetary mass binary," as do Luhman and coworkers, but it has the second lowest mass and lowest binding energy of any known binary. Oph 11 and Oph 16 belong to a newly recognized population of wide (≳100 AU), young (<10 Myr), roughly equal mass, VLM stellar and brown dwarf binaries. We deduce that ∼6% ± 3% of young (<10 Myr) VLM objects are in such wide systems. However, only 0.3% ± 0.1% of old field VLM objects are found in such wide systems. Thus, young, wide, VLM binary populations may be evaporating, due to stellar encounters in their natal clusters, leading to a field population depleted in wide VLM systems.

AB - We imaged five objects near the star-forming clouds of Ophiuchus with the Keck Laser Guide Star AO system. We resolved sources 11 (Oph 16222-2405) and 16 (Oph 16233-2402) from Allers and coworkers into binary systems. Source 11 is resolved into a 243 AU binary, the widest known for a very low mass (VLM) binary. The binary nature of source 11 was discovered first by Allers and independently here, during which we obtained the first spatially resolved R ∼ 2000 near-infrared (J and K) spectra, mid-IR photometry, and orbital motion estimates. We estimate for 11A and 11B gravities (log g > 3.75), ages (5 ± 2 Myr), luminosities [log(L/L⊙) = -2.77 ± 0.10 and -2.96 ± 0.10], and temperatures (Teff = 2375 ± 175 K and 2175 ± 175 K). We find self-consistent DUSTY evolutionary model (Chabrier and coworkers) masses of 17-5+4 M J and 14-5+6 MJ, for 11A and 11B, respectively. Our masses are higher than those previously reported (13-15 M J and 7-8 MJ) by Jayawardhana & Ivanov. Hence, we find that the system is unlikely a "planetary mass binary," as do Luhman and coworkers, but it has the second lowest mass and lowest binding energy of any known binary. Oph 11 and Oph 16 belong to a newly recognized population of wide (≳100 AU), young (<10 Myr), roughly equal mass, VLM stellar and brown dwarf binaries. We deduce that ∼6% ± 3% of young (<10 Myr) VLM objects are in such wide systems. However, only 0.3% ± 0.1% of old field VLM objects are found in such wide systems. Thus, young, wide, VLM binary populations may be evaporating, due to stellar encounters in their natal clusters, leading to a field population depleted in wide VLM systems.

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KW - Instrumentation: adaptive optics

KW - Stars: evolution

KW - Stars: formation

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KW - Stars: low-mass, brown dwarfs

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