document: in the course of an extensive search for very wide , common proper motion companions to nearby hipparcos stars from the nomad catalog @xcite , we came across an optically faint and red star at an angular separation of @xmath5 , position angle @xmath6 from the active and rapidly rotating g9v star hip 115147 ( bd + 78 826 , hd 220140 , v368 cep ) . 
   this faint star was subsequently identified with lspm j2322 + 7847 , a candidate nearby low - mass dwarf detected by @xcite from the lspm - north catalog @xcite . 
   the original identification of this star as one with significant proper motion traces to luyten ( 1967 ) where it was reported as a magnitude 17 object with @xmath7 mas  yr@xmath8  at a position angle of @xmath9 and assigned the name lp12 - 90 .    in the present paper 
   we present new @xmath2 photometry of hip 115147 , its known visual companion hip 115147b and lspm j2322 + 7847 , and obtain preliminary trigonometric parallax astrometry for the latter companion . 
   then we discuss the possible young age and origin of this interesting triple system . 
   following the identification of lspm j2322 + 7847 as a potential widely separated common proper motion companion to hip 115147 , @xmath2 photometry on the cousins system was obtained for the fainter star on ut 30 august 2005 using the 1.0-meter reflector at the flagstaff station . 
   the photometry was calibrated with an instrumental zero point term and a first order airmass term . 
   the calibration field was the standard field pg2213 - 006 from @xcite . 
   additional photometric observations were subsequently obtained on ut 16 and 17 june 2007 when the individual components of the brighter system hip 115147ab ( sep .  11 " ) were also measured . 
   the photometric results are presented in table 1 along with @xmath10 photometry extracted from 2mass , proper motions from nomad and parallax determinations . 
   the estimated uncertainties in the @xmath2 measures are @xmath11 mag in the case of lspm j2322 + 7847 and @xmath12 - 0.04 mag for the hip 115147 components where the short exposure times introduced additional error from scintillation and shutter timing . 
   since the august 2005 photometry indicated that lspm j2322 + 7847 was most likely an m - dwarf at approximately the same distance as hip 115147 , it was added to the trigonometric parallax program at usno s flagstaff station . through june 2007 
   , a total of 66 acceptable ccd observations have been accumulated on this field , covering an epoch range of 1.65 years . 
   the same tek2k ccd , observational procedures , and reduction algorithms have been employed as summarized in @xcite . using a total of 29 reference stars , the current preliminary solution yields @xmath13 mas . 
   this solution appears to be very robust , with the separate solutions for parallax in the ra and dec directions in very satisfactory agreement ( @xmath14 mas versus @xmath15 mas , respectively ) . 
   correction to absolute parallax was performed using usno @xmath16 photometry for the individual reference stars along with a calibrated @xmath17 versus @xmath18 relationship to derive a mean photometric parallax of @xmath19 mas for the 29 star ensemble . together 
   this then translates to @xmath20 mas for lspm j2322 + 7847 . 
   the star hip 115147 was identified with the bright x - ray source h2311 + 77 , which led @xcite to suggest rs cvn - type activity . 
   it was shown later on that the star is not evolved , and that it is not a short - period spectroscopic binary , justifying the currently accepted classification as a very young ,  naked " post - t tauri dwarf @xcite . 
   being one of the most powerful x - ray emitters in the solar neighborhood @xcite at @xmath21 ergs s@xmath8 @xcite , the star has the same space velocity as the local young stream ( or local association , @xcite ) . 
   this association limits its age to @xmath22 myr . 
   this stream includes isolated stars , groups and associations of diverse ages , some as young as 1 myr ( e.g. , in lupus and ophiuchus ) . 
   therefore , the assignment to this stream by itself does not lend a more precise estimation of age . 
   an x - ray luminosity of @xmath23 is typical of weak - lined tt stars in taurus - auriga - perseus , but significantly larger than that of classical tt stars ; if anything , it points at an age older than a few myr . 
   hip 115147 is listed as variable star v368 cep @xcite . 
   the slight variability allowed @xcite to determine the period of rotation of this star , 2.74 d. the fast rotation is responsible for the high degree of chromospheric and coronal activity . 
   the primary star is identified as the extreme ultraviolet source euve j@xmath24 with strong detections at @xmath25 band , as well as at 250 ev in x - rays @xcite . 
   hip 115147 is one of the 181 extreme - ultraviolet sources in the rosat wfc all - sky bright source survey identified with late - type main - sequence stars @xcite , with high signal - to noise detections in both @xmath26-@xmath27 and @xmath28-@xmath29 passbands . 
   an unusually high level of chromospheric activity of @xmath30 was determined by @xcite ; a spectral type k2v is also specified in the latter paper as opposed to g9v given in the simbad database . 
   since the rate of rotation diminishes fairly quickly with age in single stars , so does x - ray luminosity , and open clusters older than @xmath31 persei ( 50 myr ) are usually more quiescent than the youngest ones ( ic 2602 and ic 2391 ) . 
   the high degree of chromospheric and extreme ultraviolet activity suggests a very young age , possibly less than 20 myr . 
   v368 cep is more powerful in x - rays than an average k - type pleiades member by a factor of 10 , indicating an age less than 100 myr . 
   finally , the equivalent width of at @xmath32    is smaller than the upper limit for the pleiades by @xmath33    according to @xcite , which points at an age similar to the pleiades or older . 
   however , the lithium surface content is a poor estimator of age for young stars because of the large intrinsic spread of this parameter in stars of the same mass and age . 
   we are left with the most reliable and frequently used method of age estimation by model isochrones . using the photometric data from the literature and our own ( table  1 ) , we plot hr diagrams in the 2mass @xmath34 and @xmath3 , and @xmath35 passbands in figs . 
   [ jk.fig ] and [ vk.fig ] . for reference 
   , the theoretical isochrones at @xmath36 , @xmath37 and @xmath38 myr are drawn from @xcite . according to the data in @xcite derived from strmgren _ 
   uvby@xmath39 _ photometry , the star hip 115147 has a markedly subsolar metallicity at [ fe / h]@xmath40 . 
   this determination has to be taken with caution , because the photometrically derived metallicities are sensitive to the color index @xmath41 ( b. nordstrm 2007 , priv . 
   comm . ) , which may be abnormally high for chromospherically active stars @xcite . a wider range of metal abundances is supplied in the evolution models of @xcite , and we present also a 25 myr isochrone for @xmath42 from their models in fig .  [ jk.fig ] with a dashed line . 
   we find that the siess et al . 
   50 myr isochrone ( @xmath43 ) provides the best fit for all three alleged comoving components ( marked with crossed circles ) , including the secondary m dwarf hip 115147 b , separated by @xmath44 from the primary @xcite . 
   this pair is listed in the wds @xcite as wds 23194@xmath45 ( lds 2035 , discovered by luyten in 1969 ) , at separation @xmath46 and position angle @xmath47 . 
   the relative position did not change significantly between the first ac2000.2 measures taken in 1901 and the latest epoch 2000 in 2mass ( w. hartkopf & g. wycoff 2007 , priv . 
   comm . ) , confirming that the inner pair is physical . 
   the small deviation of the faintest component lspm j2322 + 7847 from the siess 50 myr isochrone appears to arise mostly from a sudden twist of the isochrone at the latest data point corresponding to mass @xmath48 . 
   we are not in a position to discuss if this twist has a certain physical meaning , but the overall match is good , and the estimated mass of the star is roughly @xmath48 . 
   the younger isochrones for 16 and 7 myr from @xcite lie significantly higher in fig . 
   [ jk.fig ] than the matching 50 myr isochrone . 
   the 25 myr isochrone from @xcite at a lower metallicity provides a poor fit to our stars , predicting much bluer colors , but these models may be strongly biased for young ages as was found by @xcite for solar - type stars in the alpha persei open cluster at 52 myr . 
   the members of the very young twa association are shown in fig . 
   [ jk.fig ] with open circles . 
   these stars are certainly much younger than hip 115147 and its companions . 
   they appear to be brighter and redder than the 7 myr isochrone corresponding to the probable age of this group ( see also * ? ? ? 
   * ) , but this deviation may be the result of the near - infrared @xmath49 and @xmath34 excess commonly observed in classical t tauri stars and attributed to a hot inner rim in their dusty accretion disks @xcite . since our stars under investigation have no accretion disks and their metal abundance may be lower , we need to find a young star with similar parameters . 
   it was pointed out by @xcite that a few young stars currently in the solar neighborhood , that traveled from the vicinity of the ophiuchus star forming region , share the moderately poor metal abundance of hip 115147 as determined from the _ 
   uvby@xmath39 _ photometry , probably affected by the high degree of chromospheric activity . 
   one of these stars is the extremely active dwarf pz tel , a likely member of the @xmath39 pic associations estimated to be 12 - 20 myr old . 
   this star is indicated with an open square in fig . 
   [ jk.fig ] . 
   its position matches the 16 myr , @xmath43 isochrone quite well . 
   pz tel is significantly brighter than hip 115147 in @xmath3 having approximately the same color ; thus , the latter star and its companions are probably older than 16 myr . 
   it is verified in fig . 
   [ vk.fig ] that this difference in @xmath50 between the two stars is not originating in a @xmath3-band excess , since both hip 115147 and lspm j2322 + 7847 match best the 52 myr , @xmath43 isochrone in a @xmath50 versus @xmath51 diagram as well . the latter star is brighter in @xmath3 than the empirically determined main sequence for field dwarfs from @xcite by 1 mag . if this star were an unrelated old m6 dwarf , its distance would be only 12 pc . 
   our trigonometric parallax ( table 1 ) yields a distance @xmath52 pc . 
   a number of stars with outstanding signs of activity and young age scattered in the solar vicinity can be traced back to their places of origin in , or close to , the ob associations in the sco - cen complex @xcite . 
   the star hip 115147 has come from the vicinity of the molecular cloud ldn 1709 in the ophiuchus star forming region , flanking the sco - cen complex at @xmath53 @xcite . 
   the closest approach to the estimated center of that association is 10.7 pc , while the separation today is 170 pc . 
   the closest approach 16 myr ago saw the star flying by at a relative velocity of 10.8 km  s@xmath8 . 
   if hip 115147 was born in the ophiuchus association , its probable age should be 16 myr , considerably younger than the previous isochrone analysis and the lithium abundance suggest . 
   because of the high departing velocity , it is more likely that this close fly - by is a chance occurrence . 
   finally , we note that the difference in proper motion between hip 115147 and lspm j2322 + 7847 , which appears to be statistically significant , may be caused by a systematic error of 5 to 10 mas  yr@xmath8   in the nomad proper motions for very faint stars . 
   the formal errors specified in nomad may be strongly underestimated for this optically dim star , whose position at the mean epoch 1979 is based on schmidt plates . the proper motion difference , if it is true , implies that the two stars are not gravitationally bound as a truly multiple system . 
   this is commonly observed among very young stars in the solar neighborhood ; for example , the common proper motion pair at mic and au mic ( approximately 10 myr old ) are separated by at least 0.23 pc and have proper motions different by @xmath54% , but their physical association is not in doubt . at the suggested age ( 20 - 50 myr ) , the hip 115147 companions are likely to stay close to each other as a moving group . 
   more accurate absolute proper motions for both companions and spectroscopic radial velocities are required to clarify the dynamical status of the system . 
   the currently available evidence is consistent with lspm j2322 + 7847 being one of the youngest , later - type stars in the near solar neighborhood . 
   we thank t. tilleman and c. dahn for taking some of the parallax images . 
   the research described in this paper was in part carried out at the jet propulsion laboratory , california institute of technology , under a contract with the national aeronautics and space administration . 
   this research has made use of the simbad database , operated at cds , strasbourg , france ; and data products from the 2mass , which is a joint project of the university of massachusetts and the infrared processing and analysis center , california technology institute , funded by nasa and the nsf . 
   ra j2000 & 23 19 26.632 & 23 19 24.53 & 23 22 53.873 + dec . j2000 & + 79 00 12.67 & + 79 00 03.8 & + 78 47 38.81 + @xmath55 & @xmath1 & & @xmath0 + proper motion & @xmath56 & @xmath57 & @xmath58 + @xmath59 & 8.60 & 13.75 & 17.99 + @xmath35 & 7.73 & 12.24 & 16.16 + @xmath60 & 7.17 & 11.04 & 14.61 + @xmath61 & 6.76 & 9.54 & 12.54 + @xmath34 & 5.90 & 8.04 & 10.42 + @xmath62 & 5.51 & 7.39 & 9.84 + @xmath3 & 5.40 & 7.20 & 9.52 +
summary: we report a late m - type , common proper motion companion to a nearby young visual binary hip 115147 ( v368 cep ) , separated by 963 arcseconds from the primary k0 dwarf . 
   this optically dim star has been identified as a candidate high proper motion , nearby dwarf lspm j2322 + 7847 by lpine in 2005 . 
   the wide companion is one of the latest post - t tauri low mass stars found within 20 pc . 
   we obtain a trigonometric parallax of @xmath0 mas , in good agreement with the hipparcos parallax of the primary star ( @xmath1 mas ) . our @xmath2 photometric data and near - infrared data from 2mass are consistent with lspm j2322 + 7847 being brighter by 1 magnitude in @xmath3 than field m dwarfs at @xmath4 , which indicates its pre - main sequence status . 
   we conclude that the most likely age of the primary hip 115147 and its 11-arcsecond companion hip 115147b is 20 - 50 myr . 
   the primary appears to be older than its close analog pz tel ( age 12 - 20 myr ) and members of the twa association ( 7 myr ) . 
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