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Thread: How often do we get close passages?

  1. #31
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    Several papers have recently focused on Scholz's Star, WISE J072003.20-084651.2, which apparently made a close flyby within human existence, though not within human history. Again, papers are listed most recent first, then on back in time. The last paper is the actual discovery paper for Scholz's Star.

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    http://adsabs.harvard.edu/abs/2018MNRAS.476L...1D

    Where the Solar system meets the solar neighbourhood: patterns in the distribution of radiants of observed hyperbolic minor bodies

    de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl; Aarseth, Sverre J.
    05/2018

    Observed hyperbolic minor bodies might have an interstellar origin, but they can be natives of the Solar system as well. Fly-bys with the known planets or the Sun may result in the hyperbolic ejection of an originally bound minor body; in addition, members of the Oort cloud could be forced to follow inbound hyperbolic paths as a result of secular perturbations induced by the Galactic disc or, less frequently, due to impulsive interactions with passing stars. These four processes must leave distinctive signatures in the distribution of radiants of observed hyperbolic objects, both in terms of coordinates and velocity. Here, we perform a systematic numerical exploration of the past orbital evolution of known hyperbolic minor bodies using a full N-body approach and statistical analyses to study their radiants. Our results confirm the theoretical expectations that strong anisotropies are present in the data. We also identify a statistically significant overdensity of high-speed radiants towards the constellation of Gemini that could be due to the closest and most recent known fly-by of a star to the Solar system, that of the so-called Scholz's star. In addition to and besides 1I/2017 U1 (`Oumuamua), we single out eight candidate interstellar comets based on their radiants' velocities.

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    http://adsabs.harvard.edu/abs/2015AJ....149..104B

    WISE J072003.20-084651.2: an Old and Active M9.5 + T5 Spectral Binary 6 pc from the Sun

    Burgasser, Adam J.; Gillon, Michaël; Melis, Carl; Bowler, Brendan P.; Michelsen, Eric L.; Bardalez Gagliuffi, Daniella; Gelino, Christopher R.; Jehin, E.; Delrez, L.; Manfroid, J.; Blake, Cullen H.
    03/2015

    We report observations of the recently discovered, nearby late-M dwarf WISE J072003.20-084651.2. New astrometric measurements obtained with the TRAPPIST telescope improve the distance measurement to 6.0 ± 1.0 pc and confirm the low tangential velocity (3.5 ± 0.6 km s-1) reported by Scholz. Low-resolution optical spectroscopy indicates a spectral type of M9.5 and prominent Halpha emission (< {{log }10}{{L}Halpha }/{{L}bol}> = -4.68 ± 0.06), but no evidence of subsolar metallicity or Li i absorption. Near-infrared spectroscopy reveals subtle peculiarities that can be explained by the presence of a T5 binary companion, and high-resolution laser guide star adaptive optics imaging reveals a faint (DeltaH = 4.1) candidate source 0\buildrel{\prime\prime}\over{.} 14 (0.8 AU) from the primary. With high-resolution optical and near-infrared spectroscopy, we measure a stable radial velocity of +83.8 ± 0.3 km s-1, indicative of old disk kinematics and consistent with the angular separation of the possible companion. We measure a projected rotational velocity of v sin i = 8.0 ± 0.5 km s-1 and find evidence of low-level variabilty (˜1.5%) in a 13 day TRAPPIST light curve, but cannot robustly constrain the rotational period. We also observe episodic changes in brightness (1%-2%) and occasional flare bursts (4%-8%) with a 0.8% duty cycle, and order-of-magnitude variations in Halpha line strength. Combined, these observations reveal WISE J0720-0846 to be an old, very low-mass binary whose components straddle the hydrogen burning minimum mass, and whose primary is a relatively rapid rotator and magnetically active. It is one of only two known binaries among late M dwarfs within 10 pc of the Sun, both of which harbor a mid T-type brown dwarf companion. We show that while this specific configuration is rare (≲1.6% probability), roughly 25% of binary companions to late-type M dwarfs in the local population are likely low-temperature T or Y brown dwarfs.

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    http://adsabs.harvard.edu/abs/2014A%26A...561A.113S

    Neighbours hiding in the Galactic plane, a new M/L dwarf candidate for the 8 pc sample

    Scholz, R.-D.
    01/2014

    Aims: Using Wide-field Infrared Survey Explorer (WISE) data and previous optical and near-infrared sky surveys, we try to identify still missing stellar and substellar neighbours of the Sun.
    Methods: When checking the brightest red WISE sources for proper motions and colours expected for nearby M and L dwarfs, we also approached the thin Galactic plane. Astrometry (proper motion and parallax measurements) and the available photometry were used to obtain first estimates of the distance and type of nearby candidates.
    Results: We have discovered WISE J072003.20-084651.2, an object with moderately high proper motion (mu ≈ 120 mas/yr) that lies at low Galactic latitude (b = +2.3°), with similar brightness (J ≈ 10.6, w2 ≈ 8.9) and colours (I - J ≈ 3.2, J - Ks ≈ 1.2, w1 - w2 ≈ 0.3) as the nearest known M-type brown dwarf LP 944-20. With a photometric classification as an M9 ± 1 dwarf, its photometric distance lies in the range between about 5 and 7 pc, based on comparison with absolute magnitudes of LP 944-20 alone or of a sample of M8-L0 dwarfs. The slightly larger distance derived from our preliminary trigonometric parallax (7.0 ± 1.9 pc) may indicate a close binary nature. The new neighbour is an excellent target for planet search and low-mass star/brown dwarf studies.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  2. #32
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    Possibly the paper that started it all.

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    http://adsabs.harvard.edu/abs/1996EM%26P...72...19M

    Encounters of the Sun with Nearby Stars in the Past and Future

    Mülläri, A. A.; Orlov, V. V.
    02/1996

    The relative space motions of the Sun and nearby stars are considered. The coordinates and velocities of the stars are taken from the Catalogue of Nearby Stars by Gliese and Jahreiss (1991). The minimum space separation between the Sun and every star as well as the corresponding moment of time are calculated by two ways. Firstly, the straight line motions are considered. Secondly, the effect of the Galaxy potential is taken into account. The Galaxy model proposed by Kutuzov and Ossipkov (1989) is used. Twenty five stars approaching the Sun closer than two parsecs are selected. The effects of the uncertainties in the observational data are studied. The influence of the encounters to the Oort cloud is discussed.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  3. #33
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    And notes about a star I have trouble finding information on in arvix

    https://en.wikipedia.org/wiki/Gamma_Microscopii
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  4. #34
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    Quote Originally Posted by Roger E. Moore View Post
    And notes about a star I have trouble finding information on in arvix

    https://en.wikipedia.org/wiki/Gamma_Microscopii
    Did you try searching with its HIP catalog number? The Google search string
    "HIP 103738" site:arxiv.org
    returned links to five papers, all discussing close-encounters. I haven't compared these results with papers you've already mentioned, though.

    Note: I've edited the list below, sorting it into order of increasing publication date, and adding the title of one of them.

    [PDF]Close encounters of the stellar kind
    https://arxiv.org/pdf/1412.3648
    by CAL Bailer-Jones - ‎2014 - ‎Cited by 24 - ‎Related articles
    Dec 11, 2014 - The nominal orbit of Hip 103738 (gamma Microscopii) rela- tive to the Sun in Galactic cylindrical coordinates (r, z,φ) over the past. 7.8Myr.

    [PDF]On the accuracy of close stellar approaches determination
    https://arxiv.org/pdf/1502.05518
    by PA Dybczyński - ‎2015 - ‎Cited by 20 - ‎Related articles
    Feb 19, 2015 - Distribution of clones of HIP 103738. Figure 9. Distribution of clones HIP 87052 nominal proximity points obtained on the basis of different astro ...

    [PDF]Finding the imprints of stellar encounters in long period comets
    https://arxiv.org/pdf/1509.07222
    by F Feng - ‎2015 - ‎Cited by 17 - ‎Related articles
    Oct 3, 2015 - encounters are HIP 103738 (gamma Microscopii) and HIP 14576. (Algol), both of which are massive and relatively slow. The radial velocity of ...

    [PDF]arXiv:1707.05277v4 [astro-ph.SR] 21 Dec 2017 [A CATALOGUE OF CLOSE ENCOUNTER PAIRS]
    https://arxiv.org/pdf/1707.05277
    by F Feng - ‎2017 - ‎Cited by 2 - ‎Related articles
    Dec 21, 2017 - HIP 103738 xh. 0.929 0.919 0.442 1.528. -3.85. -3.86. -4.18. -3.57. 17.97. 17.94. 16.67. 19.20. HIP 71683 xh. 0.976 0.976 0.947 1.007. 0.03.

    [PDF]New stellar encounters discovered in the second Gaia data release
    https://arxiv.org/pdf/1805.07581
    by CAL Bailer-Jones - ‎2018 - ‎Related articles
    May 19, 2018 - Hip 103738 (gamma Microscopii). This G6 giant was the potentially most massive encounter coming within 1pc in pa- per 1, found to have ...
    Selden

  5. #35
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    Oh! Outstanding! Thank you!

    I think arvix keeps interpreting "Microscopii" as "microscope", because of the papers I get back from a search string.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  6. #36
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    Quote Originally Posted by Roger E. Moore View Post
    Oh! Outstanding! Thank you!
    You're very welcome.
    I think arvix keeps interpreting "Microscopii" as "microscope", because of the papers I get back from a search string.
    I also tried a search using the star's formal IAU TLA "GAM Mic", but that didn't find anything. I wonder if there might be some older papers (pre-Hipparcos). Hmm. They'd probably use its Draper catalog number "HD 199951".

    [... searching ...]

    That search returns the following (again sorted by increasing date), although they don't actually predate Hipparcos:

    [PDF]XID: Cross-Association of ROSAT/Bright Source Catalog X-ray ...
    https://arxiv.org/pdf/astro-ph/0004053
    by RE Rutledge - ‎2000 - ‎Cited by 78 - ‎Related articles
    210117.46−321528.0. HD 199951. **. G4III. 5.543 : 4.677 ... ... ... ... 210117.46−321528.0. IRAS 20582−3227. IR ./. : 1RXSJ210139.7+680936. 0.0514 (0.0089).

    [PDF]Elemental Abundances of Solar Sibling Candidates
    https://arxiv.org/pdf/1405.1723
    by I Ramirez - ‎2014 - ‎Cited by 22 - ‎Related articles
    May 7, 2014 - at most ∼ 6300 K. HD 199951, on the other hand, appears to be a giant star of younger age than solar. All of our other targets have stellar ...

    [PDF]On the accuracy of close stellar approaches determination
    https://arxiv.org/pdf/1502.05518
    by PA Dybczyński - ‎2015 - ‎Cited by 20 - ‎Related articles
    Feb 19, 2015 - HD 199951. A. 1.18. -3.86. 2.36. -3.90 c, f. 110893. HD 239960. A. 1.92. 0.09. 1.92. 0.09 a, b, c, e, f a - Jiménez-Torres et al. (2011), b - Bobylev ...

    ETA1: That last was included in the previous list of papers.
    ETA2: Another source of references to papers about particular stars is Simbad, which claims that HD 199951 (or one of its 38 synonyms) is referenced in at least 71 papers since 1850. Scroll down to the bottom of
    http://simbad.u-strasbg.fr/simbad/si...bmit=submit+id
    Last edited by selden; 2018-Aug-03 at 02:20 PM.
    Selden

  7. #37
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    Thank you again!

    And a relevant recent paper...

    https://arxiv.org/abs/1808.00053

    Habitability in the Omega Centauri Cluster

    Stephen R. Kane, Sarah J. Deveny
    (Submitted on 31 Jul 2018)

    The search for exoplanets has encompassed a broad range of stellar environments, from single stars in the solar neighborhood to multiple stars and various open clusters. The stellar environment has a profound effect on planet formation and stability evolution and is thus a key component of exoplanetary studies. Dense stellar environments, such as those found in globular clusters, provide particularly strong constraints on sustainability of habitable planetary conditions. Here, we use Hubble Space Telescope observations of the core of the Omega Centauri cluster to derive fundamental parameters for the core stars. These parameters are used to calculate the extent of the Habitable Zone of the observed stars. We describe the distribution of Habitable Zones in the cluster and compare them with the stellar density and expected stellar encounter rate and cluster dynamics. We thus determine the effect of the stellar environment within the Omega Centauri core on the habitability of planets that reside within the cluster. Our results show that the distribution of Habitable Zone outer boundaries generally lie within 0.5 AU of the host stars, but that this small cross-sectional area is counter-balanced by a relatively high rate of stellar close encounters that would disrupt planetary orbits within the Habitable Zone of typical Omega Centauri stars.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  8. #38
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    Quote Originally Posted by Tom Mazanec View Post
    Gliese 710 is now expected to miss the solar system by 13,000 AU about the year 1,352,000 AD https://en.wikipedia.org/wiki/Gliese_710
    From that link:
    "There is even a 1/10,000 chance of the star penetrating into the region (d < 1,000 AU) where the influence of the passing star on Kuiper belt objects is significant."

    Eesh!

    I wonder if Gliese 710 was what was called DM61 366 in THE STARFLIGHT HANDBOOK.

  9. 2018-Aug-05, 10:34 PM

  10. #39
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    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  11. #40
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    https://arxiv.org/abs/1707.05277

    A catalogue of close encounter pairs

    Fabo Feng, Hugh R. A. Jones, Tabassum S. Tanvir
    (Submitted on 17 Jul 2017 (v1), last revised 21 Dec 2017 (this version, v4))

    We provide a catalogue of pairs of stars whose periapses are less than 1pc within the past or future 100 Myr. We use astrometric data from TGAS, Hipparcos and radial velocity data from RAVE and XHIP to find the space motions and hence the initial conditions of 229, 441 stars in Galactic coordinates. We simulate the orbits of these stars and focus on the time, distance and velocity at periastron for 8149 pairs using the k-d tree algorithm to find nearest neighbors. We find an anisotropy in the directions of encounter pairs caused by the solar apex motion, indicating a role of peculiar motion imposing an anisotropic tidal force on planetary systems. We call this effect "kinematic tide". Among the encounter pairs there are 4 encounters with the Solar System with periapses less than 1 pc and 96 pairs with periapses less than 0.1 pc. We also find 577 close encounters of stars which host planetary systems and/or debris disks. We discuss a range of uses for an encounter catalogue and present an example of how the time-varying network of stellar motions will be crucial for efficient interstellar travel between planetary systems.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  12. #41
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    Seems to be closely related to this topic.........


    https://arxiv.org/abs/1808.05531

    Photo-evaporation of proto-planetary gas discs due to flybys of external single stars in different orbits

    Yuan-Zhe Dai, Hui-Gen Liu, Wen-bo Wu, Ji-Wei Xie, Ming Yang, Hui Zhang
    (Submitted on 16 Aug 2018)

    During the evolution of proto-planetary disc, photo-evaporations of both central and external stars play important roles. Considering the complicated radiation surroundings in the clusters, where the star formed, the proto-planetary discs survive in different lifetimes due to flyby events. In this paper, we mainly focus on the disc around a T Tauri star, which encounters with another main-sequence star with different temperatures in hyperbolic orbits with different peri-center distances, eccentricities and inclinations. We find the criterion for gap-opening due to photo-evaporation of central star after the flyby event. A gap is opened in the late stage of gas disc, and induce that the gap only influence the planet formation and migration limitedly. If the flyby orbit has a moderate value of peri-center distance, which weakly depends on the eccentricity and inclination, the external photo-evaporation lead to a maximum mass loss during the flyby event. Flyby stars in orbits with smaller eccentricities or larger inclinations induce larger mass loss. Adopting a simple multiple flyby models, we conclude that in open clusters, gas discs usually survive in typical lifetimes between 1 and 10 Myr, except there are many massive stars in dense open clusters. In globular clusters, discs disperse very quickly and hardly produce the gas giant planets. The fast-depleted discs are probably responsible for the null detection of giant planets in globular clusters.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

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