Bo Reipurth

University of Hawaiʻi at Mānoa, Honolulu, Hawaii, United States

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Publications (236)787.99 Total impact

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    Bo Reipurth, Seppo Mikkola
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    ABSTRACT: We have carried out 200,000 N-body simulations of three identical stellar embryos with masses from a Chabrier IMF and embedded in a molecular core. The bodies are initially non-hierarchical and undergo chaotic motions, while accreting using Bondi-Hoyle accretion. The coupling of dynamics and accretion often leads to one or two dominant bodies controlling the center of the cloud core, while banishing the other(s) to the lower-density outskirts, leading to stunted growth. Eventually each system transforms either to a bound hierarchical configuration or breaks apart into separate single and binary components. The orbital motion is followed for 100 Myr. To illustrate the simulations we introduce the 'triple diagnostic diagram', which plots two dimensionless numbers against each other, representing the binary mass ratio and the mass ratio of the third body to the total system mass. Numerous freefloating BD binaries are formed in these simulations. The separation distribution function is in good correspondence with observations, showing a steep rise at close separations, peaking around 13 AU and then declining more gently. Unresolved BD triple systems may appear as wider BD binaries. Mass ratios are strongly peaked towards unity, as observed, but this is partially due to the initial assumptions. Eccentricities gradually increase towards higher values, due to the lack of viscous interactions in the simulations, which would both shrink the orbits and decrease their eccentricities. The main threat to newly born triple systems is internal instabilities, not external perturbations. Dynamical interactions in newborn triple systems of stellar embryos embedded in and accreting from a cloud core naturally form a population of freefloating BD binaries, and this mechanism may constitute a significant pathway for the formation of BD binaries. (Abstract abbreviated).
    01/2015;
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    ABSTRACT: We present new H$\alpha$ and H$\beta$ images of the HH~1/2 system, and we find that the H$\alpha$/H$\beta$ ratio has high values in ridges along the leading edges of the HH~1 bow shock and of the brighter condensations of HH~2. These ridges have H$\alpha$/H$\beta=4\to 6$, which is consistent with collisional excitation from the $n=1$ to the $n=3$ and 4 levels of hydrogen in a gas of temperatures $T=1.5\to 10\times 10^4$~K. This is therefore the first direct proof that the collisional excitation/ionization region of hydrogen right behind Herbig-Haro shock fronts is detected.
    11/2014;
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    ABSTRACT: We present observations of near-infrared 2.12 micro-meter molecular hydrogen outflows emerging from 1.1 mm dust continuum clumps in the North America and Pelican Nebula (NAP) complex selected from the Bolocam Galactic Plane Survey (BGPS). Hundreds of individual shocks powered by over 50 outflows from young stars are identified, indicating that the dusty molecular clumps surrounding the NGC 7000 / IC 5070 / W80 HII region are among the most active sites of on-going star formation in the Solar vicinity. A spectacular X-shaped outflow, MHO 3400, emerges from a young star system embedded in a dense clump more than a parsec from the ionization front associated with the Pelican Nebula (IC 5070). Suspected to be a binary, the source drives a pair of outflows with orientations differing by 80 degrees. Each flow exhibits S-shaped symmetry and multiple shocks indicating a pulsed and precessing jet. The `Gulf of Mexico' located south of the North America Nebula (NGC 7000), contains a dense cluster of molecular hydrogen objects (MHOs), Herbig-Haro (HH) objects, and over 300 YSOs, indicating a recent burst of star formation. The largest outflow detected thus far in the North America and Pelican Nebula complex, the 1.6 parsec long MHO 3417 flow, emerges from a 500 Solar mass BGPS clump and may be powered by a forming massive star. Several prominent outflows such as MHO 3427 appear to be powered by highly embedded YSOs only visible at a wavelength > 70 micro-meters. An `activity index' formed by dividing the number of shocks by the mass of the cloud containing their source stars is used to estimate the relative evolutionary states of Bolocam clumps. Outflows can be used as indicators of the evolutionary state of clumps detected in mm and sub-mm dust continuum surveys.
    The Astronomical Journal 09/2014; 148(6). · 4.97 Impact Factor
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    ABSTRACT: We present a deep survey of Halpha emission-line stars in the M42 region using wide-field objective prism films. A total of 1699 Halpha emission-line stars were identified, of which 1025 were previously unknown, within an area of 5.5 x 5.5 degrees centred on the Trapezium Cluster. We present Halpha strength estimates, positions, and JHKs photometry extracted from 2MASS, and comparisons to previous surveys. The spatial distribution of the bulk of the stars follows the molecular cloud as seen in CO and these stars are likely to belong to the very young population of stars associated with the Orion Nebula Cluster. Additionally, there is a scattered population of Halpha emission-line stars distributed all over the region surveyed, which may consist partly of foreground stars associated with the young NGC 1980 cluster, as well as some foreground and background dMe or Be stars. The present catalogue adds a large number of candidate low-mass young stars belonging to the Orion population, selected independently of their infrared excess or X-ray emission.
    Astronomy and Astrophysics 06/2014; · 4.48 Impact Factor
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    ABSTRACT: HH 222 is a giant shocked region in the L1641 cloud, and is popularly known as the Orion Streamers or "the waterfall" on account of its unusual structure. At the center of these streamers are two infrared sources coincident with a nonthermal radio jet aligned along the principal streamer. The unique morphology of HH 222 has long been associated with this radio jet. However, new infrared images show that the two sources are distant elliptical galaxies, indicating that the radio jet is merely an improbable line-of-sight coincidence. Accurate proper motion measurements of HH 222 reveal that the shock structure is a giant bow shock moving directly away from the well-known, very young, Herbig Be star V380 Ori. The already known Herbig-Haro object HH 35 forms part of this flow. A new Herbig-Haro object, HH 1041, is found precisely in the opposite direction of HH 222 and is likely to form part of a counterflow. The total projected extent of this HH complex is 5.3 pc, making it among the largest HH flows known. A second outflow episode from V380 Ori is identified as a pair of HH objects, HH 1031 to the northwest and the already known HH 130 to the southeast, along an axis that deviates from that of HH 222/HH 1041 by only 3.°7. V380 Ori is a hierarchical quadruple system, including a faint companion of spectral type M5 or M6, which at an age of ~1 Myr corresponds to an object straddling the stellar-to-brown dwarf boundary. We suggest that the HH 222 giant bow shock is a direct result of the dynamical interactions that led to the conversion from an initial non-hierarchical multiple system into a hierarchical configuration. This event occurred no more than 28,000 yr ago, as derived from the proper motions of the HH 222 giant bow shock.
    The Astronomical Journal 11/2013; 146(5):118-. · 4.05 Impact Factor
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    ABSTRACT: We report photometric observations for comet C/2012 S1 ISON obtained immediately after discovery (22 Sep. 2012; r = 6.28 AU) until moving into solar conjunction in mid-June 2013 using the UH2.2m, and Gemini North 8-m telescopes on Mauna Kea, the Lowell 1.8m in Flagstaff, the Calar Alto 1.2m telescope in Spain, and the VYSOS-5 and VYSOS-20 telescopes on Mauna Loa Hawai’i. An additional pre-discovery data point from the Pan STARRS1 survey extends the light curve back to 28 Jan. 2012 (r = 8.4 AU). The images showed similar tail morphology throughout this period, largely because of projection effects. Additional observations at sub-mm wavelengths using the JCMT on 15 nights between 9 March (r = 4.52 AU) and 16 June 2013 (r = 3.35 AU) were used to search for CO J(3-2), CO J(2-1), HCN J(4-3), and HCN J(3-2) rotation lines. No gas was detected, with preliminary upper limits for CO during 14-15 June (r = 3.3 AU) of Q < 6.4 x 10^27 molec/s based on the observations of the CO J(2-1) line. Using these production rates, the Q(H2O) published by Schleicher (2013; IAUC 9254), and the preliminary radius from the HST measurements (J.-Y. Li et al., 2013; STScI-2013-14) we have generated ice sublimation models consistent with the photometric light curve. The inbound light curve is likely controlled by sublimation of CO or CO2; at these distances water is not a strong contributor to the outgassing. Without more sensitive limits on CO, we cannot yet constrain which of these volatiles is controlling the activity. It is clear from the photometric light curve that the fractional active area of the nucleus increased linearly by about a factor of 2 from Jan. 2012 until mid Jan. 2013 (r ~ 5 AU) at which point the activity decreased by 30% by early May 2013. This suggests that a limited supply of volatile material was driving the current activity.
    10/2013;
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    ABSTRACT: We report photometric observations for comet C/2012 S1 (ISON) obtained during the time period immediately after discovery (r=6.28 AU) until it moved into solar conjunction in mid-2013 June using the UH2.2m, and Gemini North 8-m telescopes on Mauna Kea, the Lowell 1.8m in Flagstaff, the Calar Alto 1.2m telescope in Spain, the VYSOS-5 telescopes on Mauna Loa Hawaii and data from the CARA network. Additional pre-discovery data from the Pan STARRS1 survey extends the light curve back to 2011 September 30 (r=9.4 AU). The images showed a similar tail morphology due to small micron sized particles throughout 2013. Observations at sub-mm wavelengths using the JCMT on 15 nights between 2013 March 9 (r=4.52 AU) and June 16 (r=3.35 AU) were used to search for CO and HCN rotation lines. No gas was detected, with upper limits for CO ranging between (3.5-4.5)E27 molec/s. Combined with published water production rate estimates we have generated ice sublimation models consistent with the photometric light curve. The inbound light curve is likely controlled by sublimation of CO2. At these distances water is not a strong contributor to the outgassing. We also infer that there was a long slow outburst of activity beginning in late 2011 peaking in mid-2013 January (r~5 AU) at which point the activity decreased again through 2013 June. We suggest that this outburst was driven by CO injecting large water ice grains into the coma. Observations as the comet came out of solar conjunction seem to confi?rm our models.
    The Astrophysical Journal 09/2013; 776(2013-10-03-2). · 6.28 Impact Factor
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    ABSTRACT: Our general understanding of multiple star and planet formation is primarily based on observations of young multiple systems in low density regions like Tau-Aur and Oph. Since many, if not most, of the stars are born in clusters, observational constraints from young binaries in those environments are fundamental for understanding both the formation of multiple systems and planets in multiple systems throughout the Galaxy. We build upon the largest survey for young binaries in the Orion Nebula Cluster (ONC) which is based on Hubble Space Telescope observations to derive both stellar and circumstellar properties of newborn binary systems in this cluster environment. We present Adaptive Optics spatially-resolved JHKL'-band photometry and K-band R$\sim$\,5000 spectra for a sample of 8 ONC binary systems from this database. We characterize the stellar properties of binary components and obtain a census of protoplanetary disks through K-L' color excess. For a combined sample of ONC binaries including 7 additional systems with NIR spectroscopy from the literature, we derive mass ratio and relative age distributions. We compare the stellar and circumstellar properties of binaries in ONC with those in Tau-Aur and Oph from samples of binaries with stellar properties derived for each component from spectra and/or visual photometry and with a disk census obtained through K-L color excess. The mass ratio distribution of ONC binaries is found to be indistinguishable from that of Tau-Aur and, to some extent, to that of Oph in the separation range 85-560\,AU and for primary mass in the range 0.15 to 0.8\,M$_{\sun}$.A trend toward a lower mass ratio with larger separation is suggested in ONC binaries which is not seen in Tau-Aur binaries.The components of ONC binaries are found to be significantly more coeval than the overall ONC population and as coeval as components of binaries in Tau-Aur and Oph[...]
    Astronomy and Astrophysics 07/2013; · 4.48 Impact Factor
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    Josh Walawender, Bo Reipurth, John Bally
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    ABSTRACT: We have searched the Lynds 988 dark cloud complex for optical (\ha{} and \sii{}) and near-IR (\mh{} 2.12 $\mu$m) shocks from protostellar outflows. We find 20 new Herbig-Haro objects and 6 new \mh{} shocks (MHO objects), 3 of which are cross detections. Using the morphology in the optical and near-IR, we connect several of these shocks into at least 5 distinct outflow systems and identify their source protostars from catalogs of infrared sources. Two outflows in the cloud, from IRAS 21014+5001 and IRAS 21007+4951, are in excess of 1 pc in length. The IRAS 21007+4951 outflow has carved a large cavity in the cloud through which background stars can be seen. Also, we have found an optical shock which is the counterflow to the previously discovered "northwest outflow" from LkHa 324SE.
    The Astronomical Journal 07/2013; 146(3). · 4.97 Impact Factor
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    ABSTRACT: We present a study of the nearby isolated star forming region B62, a well-defined Bok globule in northern Ophiuchus. On large scales, we identify the H-alpha emission line stars, several of which are associated with compact reflection nebulae, together with two large Herbig-Haro flows, named HH 1000 and HH 1001. On small scales, we focus on the young stellar object IRAS 17130-2053 located near the center of the globule. This embedded Class I source is found to be a binary in our near-infrared images, and drives the bipolar Herbig-Haro flow HH 1000 as well as a molecular outflow. We present new interferometric observations by the Submillimeter Array and study the molecular environment in multiple dense gas tracers with high resolution.
    07/2013;
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    ABSTRACT: Multiple systems have long been used to probe the origin and evolution of stars of all masses. Only in the past 10-15 years have such studies been extended to brown dwarfs and the lowest mass stars through binary surveys of both young star forming regions and the older field population. In addition, a groundswell of interest in M dwarfs in recent years has resulted in large, modern datasets for these most common stars in the Galaxy, thereby enabling renewed perspectives on their multiplicity properties. These latest observational results have in turn fueled the many theories competing to explain the formation of low-mass stars and brown dwarfs. This Cool Stars 17 splinter session examined the current state of this field by reviewing results from the numerous observational techniques - radial velocities, astrometry, direct imaging, and synoptic surveys - that have been used to study multiplicity from the earliest embedded protostars to objects in young star forming regions, old and intermediate-age clusters, as well as the more heterogeneous field population.
    Astronomische Nachrichten 02/2013; · 1.12 Impact Factor
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    Bo Reipurth, Seppo Mikkola
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    ABSTRACT: The formation of very wide binary systems, such as the α Centauri system with Proxima (also known as α Centauri C) separated from α Centauri (which itself is a close binary A/B) by 15,000 astronomical units (1 au is the distance from Earth to the Sun), challenges current theories of star formation, because their separation can exceed the typical size of a collapsing cloud core. Various hypotheses have been proposed to overcome this problem, including the suggestion that ultrawide binaries result from the dissolution of a star cluster-when a cluster star gravitationally captures another, distant, cluster star. Recent observations have shown that very wide binaries are frequently members of triple systems and that close binaries often have a distant third companion. Here we report N-body simulations of the dynamical evolution of newborn triple systems still embedded in their nascent cloud cores that match observations of very wide systems. We find that although the triple systems are born very compact-and therefore initially are more protected against disruption by passing stars-they can develop extreme hierarchical architectures on timescales of millions of years as one component is dynamically scattered into a very distant orbit. The energy of ejection comes from shrinking the orbits of the other two stars, often making them look from a distance like a single star. Such loosely bound triple systems will therefore appear to be very wide binaries.
    Nature 12/2012; · 42.35 Impact Factor
  • John Bally, Josh Walawender, Bo Reipurth
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    ABSTRACT: We report the discovery of new Herbig-Haro shocks in the southeastern portion of the Taurus molecular cloud complex. The embedded protostar IRAS04325+2402, located in the eastern end of the B18 dark cloud in the cloud region known as L1535, drives a parsec-scale outflow with a length of at least 134' (5.5 pc) toward P.A. = 17°/197° making this the largest protostellar outflow found thus far in Taurus. The southern terminus of this flow located about 65' (~2.7 pc) from the IRAS source consists of a large previously discovered shock, HH 434-436. The northern lobe contains three faint shocks with the most distant being HH 696 located 2.8 pc north of the source. Two smaller shocks, HH 699 and HH 703, are found midway between the IRAS source and HH 434-436. HH 703 has a proper motion of 170 ± 30 km s–1 toward P.A. = 195° ± 10°. Additionally, we report the discovery of a dozen new Herbig-Haro objects tracing outflows and protostellar jets in B18 and near IC 2087, at least two of which have also attained parsec-scale dimensions. These observations demonstrate that some low-mass stars forming from the Taurus clouds drive giant flows which can excite shocks in the inter-cloud medium degrees from their sources, providing further evidence for the generation of large-scale mass motions and turbulence by protostellar outflows.
    The Astronomical Journal 10/2012; 144(5):143. · 4.97 Impact Factor
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    ABSTRACT: We present a study of the HH 110/270 system based on three sets of optical images obtained with the ESO New Technology Telescope, the Subaru Telescope, and the Hubble Space Telescope (HST). The ground-based observations are made in the H{alpha} and [S II] emission lines and the HST observations are made in the H{alpha} line only. Ground-based observations reveal the existence of nine knots, which have not been previously discussed and offer some important insight into the HH 110/270 history. We perform a kinematic study of the HH 110/270 system and an analysis of its emission properties. We measure proper motions of all the knots in the system. Four of the newly identified knots belong to the HH 270 jet. Their positions indicate that the jet's axis changed its direction in the past. We speculate that similar changes may have occurred many times in the past and this could be part of the reason for the unusual structure of the HH 110 jet. The HST observations allow us to resolve individual knots into their substructures and to measure their proper motions. These measurements show that the knots are highly turbulent structures. Finally, we report the discovery of four new Herbig-Haro (HH) objects located near the HH 110/270 system.
    The Astronomical Journal 05/2012; 143(5). · 4.97 Impact Factor
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    Bo Reipurth, Colin Aspin, G. H. Herbig
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    ABSTRACT: Detailed observations of a recently recognized eruptive variable, V900 Mon, are presented. The star is located in the small cloud L1656, a little-studied region of modest star formation activity in Monoceros, and is presently at a magnitude of r ~ 16, surrounded by a bright compact reflection nebula, where only a 20th magnitude star was seen on the red first-epoch POSS plate. Optical spectra show a red absorption-line spectrum not later than mid-K, and the Hα line and the Na I D 12 doublet display prominent P Cygni profiles with massive absorption troughs indicating a cool outflowing wind. Near-infrared spectra show deep CO bandhead absorption and pronounced molecular bands of water vapor indicative of a much cooler object. This spectral appearance is very similar to that of FU Orionis, except that V900 Mon has a much higher reddening of AV ~ 13 mag. The energy distribution of V900 Mon, compiled from non-simultaneous observations and thus dependent on possible luminosity changes, shows that V900 Mon is a Class I protostar with a massive cool envelope. At a distance of about 1100 pc, V900 Mon has a luminosity of 106 L ☉ in the range of 0.55-160 μm. These data identify V900 Mon as a new member of the rare class of FU Orionis variables.
    The Astrophysical Journal Letters 02/2012; 748(1):L5. · 5.60 Impact Factor
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    ABSTRACT: CBET 2795 available at Central Bureau for Astronomical Telegrams.
    Central Bureau Electronic Telegrams. 08/2011;
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    ABSTRACT: New GCVS names are announced for several young variable stars of special astrophysical interest. These stars will enter the 80th Name List of Variable Stars but are given GCVS names now in order to make it possible for investigators to use permanent names in their publications.
    Peremennye Zvezdy. 05/2011;
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    T Armond, B Reipurth, J Bally, C Aspin, ⋆⋆
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    ABSTRACT: We present an optical/infrared study of the dense molecular cloud, L935, dubbed "The Gulf of Mexico", which separates the North America and the Pelican nebulae, and we demonstrate that this area is a very active star forming region. A wide-field imaging study with interference filters has revealed 35 new Herbig-Haro objects in the Gulf of Mexico. A grism survey has identified 41 Hα emission-line stars, 30 of them new. A small cluster of partly embedded pre-main sequence stars is located around the known LkHα 185-189 group of stars, which includes the recently erupting FUor HBC 722.
    Astronomy and Astrophysics 03/2011; 528. · 4.48 Impact Factor
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    ABSTRACT: We present an optical/infrared study of the dense molecular cloud, L935, dubbed "The Gulf of Mexico", which separates the North America and the Pelican nebulae, and we demonstrate that this area is a very active star forming region. A wide-field imaging study with interference filters has revealed 35 new Herbig-Haro objects in the Gulf of Mexico. A grism survey has identified 41 Halpha emission-line stars, 30 of them new. A small cluster of partly embedded pre-main sequence stars is located around the known LkHalpha 185-189 group of stars, which includes the recently erupting FUor HBC 722.
    01/2011;

Publication Stats

3k Citations
787.99 Total Impact Points

Institutions

  • 2010–2014
    • University of Hawaiʻi at Mānoa
      • Institute of Astronomy
      Honolulu, Hawaii, United States
  • 2012
    • Instituto de Geofísica
      Coyoacán, The Federal District, Mexico
  • 2002–2012
    • University of Hawaiʻi at Hilo
      Hilo, Hawaii, United States
  • 2008–2009
    • University of Hawai'i System
      Honolulu, Hawaii, United States
    • National Taiwan University
      • Department of Physics
      T’ai-pei, Taipei, Taiwan
    • National Taiwan Normal University
      T’ai-pei, Taipei, Taiwan
  • 2002–2008
    • Honolulu University
      Honolulu, Hawaii, United States
  • 1998–2008
    • University of Colorado at Boulder
      • • Center for Astrophysics and Space Astronomy
      • • Department of Astrophysical and Planetary Sciences
      Boulder, CO, United States
    • Universidad Nacional Autónoma de México
      • Institute of Astronomy
      Ciudad de México, The Federal District, Mexico
  • 1992–2006
    • University of Victoria
      • Department of Physics and Astronomy
      Victoria, British Columbia, Canada
    • Kokugakuin University
      Edo, Tōkyō, Japan
  • 2004
    • Ruhr-Universität Bochum
      Bochum, North Rhine-Westphalia, Germany
  • 2002–2003
    • The University of Arizona
      Tucson, Arizona, United States
  • 1997–1999
    • University of Colorado
      Denver, Colorado, United States
  • 1993–1994
    • University of Santiago, Chile
      CiudadSantiago, Santiago, Chile
    • University of Houston – Victoria
      Houston, Texas, United States