E-BOSS: an Extensive stellar BOw Shock Survey. I: Methods and First Catalogue
C. S. Peri, P. Benaglia, D. P. Brookes, I. R. Stevens, N. Isequilla
AAstronomy & Astrophysics manuscript no. E-BOSS˙AA.final c (cid:13)
ESO 2018October 16, 2018
E-BOSS: An Extensive stellar BOw Shock Survey. I: Methods andFirst Catalogue
C. S. Peri , , P. Benaglia , , D. P. Brookes , I. R. Stevens , and N. Isequilla Instituto Argentino de Radioastronom´ıa, CCT-La Plata (CONICET), C.C.5, (1894) Villa Elisa, Argentinae-mail: [email protected] Facultad de Ciencias Astron´omicas y Geof´ısicas, UNLP, Paseo del Bosque s / n, (1900) La Plata, Argentina School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UKReceived Month number, 2011; accepted Month number, 2011
ABSTRACT
Context.
Bow shocks are produced by many astrophysical objects where shock waves are present. Stellar bow shocks, generated byrunaway stars, have been previously detected in small numbers and well-studied. Along with progress in model development andimprovements in observing instruments, our knowledge of the emission produced by these objects and its origin can now be moreclearly understood.
Aims.
We produce a stellar bow-shock catalogue by applying uniform search criteria and a systematic search process. This catalogueis a starting point for statistical studies, to help us address fundamental questions such as, for instance, the conditions under wich astellar bow shock is detectable.
Methods.
By using the newest infrared data releases, we carried out a search for bow shocks produced by early-type runaway stars.We first explored whether a set of known IRAS bow shock candidates are visible in the most recently available IR data, which hasmuch higher resolution and sensitivity. We then carried out a selection of runaway stars from the latest, large runaway catalogueavailable. In this first release, we focused on OB stars and searched for bow-shaped features in the vicinity of these stars.
Results.
We provide a bow-shock candidate survey that gathers a total of 28 members which we call the Extensive stellar BOw ShockSurvey (E-BOSS). We derive the main bow-shock parameters, and present some preliminary statistical results on the detected objects.
Conclusions.
Our analysis of the initial sample and the newly detected objects yields a bow-shock detectability around OB stars of ∼
10 per cent. The detections do not seem to depend particularly on either stellar mass, age or position. The extension of the E-BOSSsample, with upcoming IR data, and by considering, for example, other spectral types as well, will allow us to perform a more detailedstudy of the findings.
Key words.
Astronomical data bases: catalogs – stars: early-type – Infrared: ISM – Infrared: stars
1. Introduction
Many astrophysical objects perturb the interstellar medium andproduce di ff erent kinds of observable structures. Early-type starswith large peculiar velocities (termed runaway stars) are one ex-ample of the perturbing agent. They are responsible for the gen-eration of stellar bow shocks.Runaway stars have been studied for several decades. Thereare currently two proposed mechanisms for the origin of theirhigh velocities (Hoogerwerf et al. 2000). One is the binary super-nova scenario (BSS, Zwicky 1957, Blauuw 1961) and the otheris the dynamical ejection scenario (DES, Poveda et al. 1967,Gies & Bolton 1986). In the BSS, the runaway star that wasoriginally part of a binary system, acquires a high speed when itscompanion explodes as a supernova. In the context of the DES,the runaway star achieves its velocity thanks to the dynamicalinteraction with one or more stars. In some cases, the trajectoryof the stars and the original systems can be reconstructed, andthe mechanism that has kicked the star can be identified. Thegathered evidence has not always enabled strong conclusions tobe made (see for instance the dissenting findings by Comer´on &Pasquali 2007 and Gvaramadze & Bomans 2008). Studies suchas Mo ff at et al. (1998) of runaway stars suggest that the BSS isslightly more likely, and that those stars with significant peculiar supersonic motion relative to the ambient ISM, tend to form bowshocks in the direction of the motion.Abundant studies of individual or smaller groups of runawaystars can be found. However, compilations of large number ofhigh velocity stars are scarce. A good example is the GalacticO-Star Catalog (GOSC, Ma´ız Apell´aniz et al. 2004), which con-tains the physical properties of about 40 of these stars. Tetzla ff et al. (2010) carried out an extensive kinematical and probabil-ity study, that allowed us to identify thousands of runaway stars.The authors used the Hipparcos catalogue (Perryman et al. 1997)and built a database of ∼ ff ects of runaway stars on the environment and the in-teraction between those stars and the interstellar medium (ISM)have been widely documented. A fundamental contribution canbe found in Van Buren and McCray (1988), who presented a listof 15 bow shock-like candidates, found while studying GalacticHII regions detected in IRAS (Infrared Astronomical Satellite)data. Their study triggered an extended search for stellar bow-shock candidates, which resulted in almost 60 similar sourcesof which around 20 were actually candidates (Van Buren et al.1995, Noriega-Crespo et al. 1997: NC97). Some of the candi-dates were studied by Brown & Bomans (2005), using the H α all-sky survey (SHASSA / VTSS). They searched images of 37objects of the list of Van Buren et al. (1995) and detected 8 bowshocks. They also calculated environmental parameters and in all a r X i v : . [ a s t r o - ph . S R ] D ec eri et al.: The Extensive stellar BOw Shock Survey the cases they found consistency with the features of the warmionized medium.In the past few years, searches of relatively small sky re-gions have revealed more stellar bow shocks. Povich et al. (2008)reported the discovery of six stellar bow shocks in the star-forming regions M 17 and RCW 49 from Spitzer GLIMPSE(Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) im-ages. By combining 2MASS (Two Micron All-Sky Survey),Spitzer, MSX (Midcourse Space eXperiment), and IRAS data,they obtained the SEDs of the bow shocks and stars associ-ated with them. Other 10 bow-shock candidates were found byKobulnicky et al. (2010) using mid-IR images from the SpitzerSpace Telescope Cygnus X Legacy Survey. Arnal et al. (2011)exposed a study of the surrounding emission related to the starHD 192281, a member of the OB association Cygnus OB8.They analyzed neutral hydrogen, radio continuum, moleculargas (CO) emission and infrared (IR) data, and derived several pa-rameters of the medium. They concluded that HD 192281 seemsto generate a stellar bow shock and it is possible that triggeredstar formation is underway. Bow shocks have been seen aroundsome massive X-ray binaries, such as Vela X-1 (Kaper et al.1997) and 4U 1907 +
09 (Gvaramadze et al. 2011a).Gvaramadze et al. (2011b) carried out a search for OB starsrunning away from the young stellar cluster NGC 6357. Theydiscovered seven bow shocks, and thoroughly discussed the sce-nario for these structures to develop.During the investigation of the outskirts of Cygnus OB2,Comer´on & Pasquali (2008) discovered a bow-shaped structureclose to the high mass runaway star BD + ◦ + ◦ ff erent radiative processes.In spite of these studies, numerous questions remain to beanswered. How common are stellar bow shocks? In which con-ditions are they produced and detected? Questions such as howthe spectral type, velocity, stellar wind, coordinates of the star,and other parameters influence the formation of a bow shock willbe more clearly addressed as more examples are analyzed.In this paper, we introduce the Extensive BOw Shock Survey(E-BOSS) generated by means of on-line available data fromdi ff erent missions. We used the first-release Wide-field InfraredSurvey Explorer (WISE) images, as a tool to detect new struc-tures and to contribute to what is known about those alreadystudied.In the next section, we briefly discuss the theoretical back-ground and analyze the conditions that could increase the prob-ability of detecting a stellar bow shock. Section 3 describes theprocedure followed to obtain the sample in which we search forbow-shock candidates. In Section 4, we present the bow shocksfound and characterize them. Section 5 shows the statistics per-formed, and Sect. 6 has a corresponding discussion. In the lastsection, we comment on the immediate prospects.
2. Theoretical considerations
Runaway stars move through the interstellar medium (ISM) withvelocities that overcome the field stars velocities and the soundof speed in the ISM. They shock the ISM and produce the so-called bow shocks that sweep up the ISM matter into thin, denseshells (Wilkin 1996). The theoretical study of bow shocks hasbeen developed not only from an analytical point of view butalso with numerical simulations.Wilkin (1996) derived analytical exact solutions for stellarwind bow shocks in the thin-shell limit, stressing the importanceof the conserved momentum within the shell. He developed asimple method to reproduce the shape of the shell, mass col-umn, and velocity of the shocked gas throughout the shell. Later,Wilkin (2000) improved the model studying the modifications ofthe bow shocks in two cases where: (i) a star moves superson-ically with respect to an ambient medium with a density gra-dient perpendicular to the stellar velocity, and (ii) a star with amis-aligned, axisymmetric wind moves in a uniform medium.He found that the region of the stand-o ff point (where ambientand wind pressures balance each other) is tilted in both cases.In that way, the star does not lie in the line that divides the bowshock into two halves.Dgani et al. (1996a, 1996b) peformed a stability analysisof thin isothermal bow shocks. In the first paper, they showedthat the bow shocks produced by stars with fast stellar winds aremore stable than those generated by slow winds. In the secondarticle, the authors then investigated non-linear instabilities andrun numerical simulations to solve the problem. They proposedthat the slower the wind, the highest the instability. They also ap-plied the model to the star α Cam and concluded that the clumpsobserved might be explained by the instabilities.Comer´on & Kaper (1998) conducted a semi-analytical studyof bow shocks produced by OB runaway stars and derived ex-pressions that suggest di ff erent results from those obtained withthe assumption of instantaneous cooling of the shocked gas(Wilkin 1996). They ran numerical simulations that reveal awealth of details in the formation, structure, and evolution of thebow shocks. These features strongly depend on the conditions ofthe medium and star. The bow shocks can either form or not; andif they do form, they can be either stable, unstable, or layered.To complete the study of bow shocks and improve the mod-els, they need to be observed and analyzed. In principle, owingto the presence of the shocks that the runaway stars produce inthe ISM, the dust is heated and in that way re-radiates at infraredwavelengths. As we describe in other sections, bow shocks havebeen observed at infrared (e.g. van Buren et al. 1995, NC97),optical (e.g. Brown & Bomans 2005), and -in a few cases- ra-dio wavelengths, and will eventually be detected at high energywaves (Benaglia et al. 2010).
3. The making of the E-BOSS sample
We searched for stellar bow shocks in various di ff erent databasesdescribed later. We account for a number of criteria that help usto identify new stellar bow shocks.1. We examined the surroundings of early-type runaway stars,as these have high velocities and strong winds that sweep upinterstellar matter and also high luminosities that contributeto the dust heating.2. We selected nearby stars ( d < We generated the initial sample in two di ff erent ways. Weconsidered first bow shock candidates that had previously beendetected in the IRAS data (NC97). Secondly, we carried out asystematic search around runaway stars that could produce bowshocks, using the catalogue of Tetzla ff et al. (2010). The nextsection describes the process in more detail. In the rest of thepaper, we divide the E-BOSS sample into two groups, groups 1and 2. For this group, we took the bow shock candidates database ofNC97. These authors searched for bow shocks and other featuresat IR wavelengths from the HiReS-IRAS maps. Table 1 lists the56 objects that are OB stars from NC97, hereafter called group 1(the WR stars HD 50896 and HD 192163, from the original list,were excluded).
The second group was extracted from the catalogue of Tetzla ff et al. (2010). From a sample of 7663 young stars observed byHipparcos (Perryman et al. 1997), the authors built a catalogueof 2546 runaway stars candidates. Their study lists stellar names,velocities, spectral types, ages, and masses. From this last list,we found 244 stars of spectral type O to B2. We list this 244stars in Table 2; they comprise what we call hereafter group 2. Atotal of 17 stars are common to both groups. We used the NASA / IPAC Infrared Science Archive to gatherrelevant infrared and sub-millimeter missions data (IRAS, MSX,WISE, Spitzer, etc). In practice, data from MSX and WISE haveproven to be the most useful. In particular, WISE has discoveredvarious bow shocks. Although the published WISE data covershalf of the sky, in e ff ect, it covers more than two thirds of bothgroup 1 and group 2 samples. When further data becomes avail-able, it will be added to a subsequent release of the E-BOSSsample.In addition to the infrared data, we searched for bow shockemission at H α , using the Virginia Tech. Spectral Survey (VTSS,Dennison et al. 1997) and the Southern Hemispheric H α SkySurvey Atlas (SHASSA, Gaustad et al. 2001). These surveyscover most of the sky with a spatial resolution of 0.8 (cid:48) forSHASSA and 1.6 (cid:48) for VTSS. We did not find any convincingbow shock candidates for either our group 1 or group 2 sample.This is in contrast to Brown & Bomans (2005), who found 8possible bow shock candidates, starting with a target list of 37stars from van Buren et al. (1995). We note that the stars areoften located in complex H α emission regions making identifi-cation of a bow shock feature di ffi cult. In some cases, we diddetect possible H α emission from a bow shock but which is notcoincident with a clear bow shock detected by WISE (for exam-ple, HD 48099 and HD 149757). In these cases, we relied on theinfrared detection.The detection of radio emission and the measurement of anon-thermal radio spectral index coincident with the location ofthe bow-shock candidate related to the star BD + ◦ http: // irsa.ipac.caltech.edu / http: // wise.ssl.berkeley.edu / NRAO / VLA Sky Survey (NVSS, Condon et al. 1998), whichreturns radio images of the sky in various formats. Most of theradio maps contain only point sources, which are not particularlyrelated to the IR features. However, three E-BOSS objects, apartfrom BD + ◦
4. Results
We searched for WISE and MSX data toward the 56 group-1 tar-gets, at all available wavelengths, with a field size of 1 sq degree.About 55% of the targets have MSX data, and 70% have WISEdata. Table 1 gives the Hipparcos number, alternative names, andthe spectral type of the stars as in NC97, or updated from GOSC(Ma´ız Apell´aniz et al. 2004) whenever possible. Columns 4 and5 list the results obtained with MSX and WISE. We identifiedseveral types of structures around the stars that are representedwith di ff erent symbols in Table 1. The categories are: a pointsource at the position of the star, di ff use emission in the vicinityof the star, no emission, a bow-shaped emission feature, a bub-ble candidate, and extended emission in the field. A ’?’ symbolimplies doubtful feature. The last column reproduces the resultsof NC97. Two special cases are noted in the table. Cappa et al.(2008) studied the environs of HD 92206, and identified an ex-tended HII region. The star HD 36862 is very close to HD 36861(O8III); they both belong to the rich cluster λ Ori (Bouy et al.2009), are not single isolated objects, and have a large spatialvelocity. In both cases, a bow shock might be hidden and wediscarded these two objects from our sample.We found 18 bow-shock candidates (BS-C) out of the 56stars of group 1 (Table 1). Of the 18 BS-C, 3 of them were de-tected with MSX (one is the case of BD + ◦ ff erent results betweenGroup 1 stars and NC97 are due to the high resolution and sen-sitivity of the more recent data. We list the 244 O-B2 runaway candidates extracted from Tetzla ff et al. (2010) in Table 2. We searched the WISE data to identifyBS-C. The table is divided into two parts: the upper part containsthose stars for which WISE data were released, and the lowerportion where they were not.We found a total of 17 BS-C, marked with bold font in thetop part of Table 2; seven of them had been identified in group 1. The 28 objects of the E-BOSS sample are shown in Figures 1 to5. In Table 3, the star name is given in the first column, the groupmembership in column 2, and Galactic coordinates in columns 3and 4. Spectral types are in column 5. The distances, in column6, were taken from several sources, namely Megier et al. (2009),Mason et al. (1998), Schilbach & R¨oser (2008), Hanson (2003),and Thorburn et al. (2003), or derived from Hipparcos parallaxes(van Leeuwen 2007). The wind terminal velocities v ∞ are either from Howarth et al. (1997) or derived using table 3 of Prinja etal. (1990). To compute the stellar mass-loss rates ˙ M , we usedthe routine described by Vink et al. (2001), and stellar parame-ters derived from standard models (e.g. Martins et al. 2005). Thestellar tangential velocities v tg were taken from Tetzla ff et al.(2010), or derived from proper motions (van Leeuwen 2007, seelast two columns of Table 3). Radial velocities v r are from theSecond Catalogue of Radial Velocities with Astrometric Data(Kharchenko et al. 2007).In Figs. 1 to 5, we show the WISE and MSX images of the28 BS-C. Superimposed on the images, we have plotted witharrows two directions, representing the proper motion of the starderived by van Leeuwen (2007), and that of the corrected propermotion after taking into account the Galactic rotation of the ISMat the location of the star (as done for example in Comer´on &Pasquali 2007 and Mo ff at et al. 1998, 1999).For each BS-C, we measured geometrical parameters, suchas the spatial extent l , the width w , and the distance from the starto the midpoint of the bow shock structure R (Table 4, columns2 to 7).The ISM ambient density in the vicinity of the star n ISM canbe estimated using the expression that gives the so-called stag-nation radius R (see Wilkin 1996 for definition and details) R = (cid:115) ˙ Mv ∞ πρ a v ∗ , where the ambient medium density is ρ a = µ n ISM and v ∗ is thespatial stellar velocity. We estimated the volume density of theISM in H atoms at the bow shock position assuming R ∼ R , amass per H atom µ = . × − g, and the helium fractionalabundance Y = .
1. The values obtained for n ISM are given incolumn 8 of Table 4, and should be interpreted with caution. Inmany cases, the width of the bow shock is substantial comparedto R , which adds an uncertainty to the R values used in the lastequation.There are additional factors that might a ff ect the values of R and n ISM , such as errors in the mass-loss rate due to clumping, inaddition to the potential source of errors in the parameters used,as described above.
5. Statistics
In Figs. 6-7, we present the ( l , b ) distribution of group 1 andgroup 2 stars, showing those with and without bow shocks. Theredoes not seem to be any preferential location for stars with bowshocks. We note that there are no bow shocks at high latitudes,but that the small number of stars there means we cannot sayanything conclusive.Figs. 8-9 show the occurrence of bow shocks as a functionof spectral type for each group. We might have expected moredetections of bow shocks from the more massive, earlier-type,or fastest stars, which is not seen. The number of stars in eachsubtype grows with later spectral types, probably reflecting thatthere is no strong bias in the Group 2 stellar sample.Figs. 10-11 show that bow shocks were detected around boththe lower mass stars and the youngest stars, but the very smallnumbers in many of the bins prevents us to draw any clear con-clusion.
6. Discussion
The E-BOSS sample introduced here constitutes the most sub-stantial sample of stellar bow shocks and should provide a reli- able basis to more detailed studies of the structure and formationof bow shocks.For group 1, the availability of MSX and WISE images hasenabled us to improve previous results, which relied on the IRASdata. Some structures were identified as bow shocks, others re-jected, and in some cases new bow shocks were revealed. One in-teresting example is the feature around HD 34078 (HIP 24575).The IRAS data, discussed in NC97, revealed an excess of emis-sion at 60 µ m, but no discernible bow shock. With the WISEbands, two structures can be clearly seen (Fig. 2). There are fil-aments around the star mainly at longer wavelengths (red = = = ∼
10 per cent). On the basis of these statistics, we wouldexpect to find around 8 additional bow shock candidates in theremaining 80 group 2 sources.Returning to the detected BS-C, several bow shocks in bothgroup 1 and group 2 show a complex layered structure, suchas HD 30614 (HIP 22783), HD 42933 (HIP 29276), and HD15629 (HIP 11891). In many cases, but not all, the structuresare aligned with the stellar velocity. An example of a misalignedbow shock candidate is HD 36512 (HIP 25923). We include thisobject in the sample because at this stage we lack any preciseknowledge of the true stellar velocity.HD 48099 (HIP 32076) is maybe the most classic exampleof a bow shock, and this object will be the subject of a future de-tailed study that will include modeling of the infrared emissionin the formation of a bow shock del Valle et al., in preparation).With this sample, we will be able to investigate the IR lu-minosity and dust temperature and compare the scaling of thesequantities with stellar parameters (van Buren & McCray 1998),and also detectability (Stevens et al., in preparation).The current sample is insu ffi ciently large to distinguish prop-erties according to stellar luminosity class, binarity status, or par-ticular stellar classes, such as Of-type stars. However, when newdata are released, the situation will improve.
7. Summary and prospects
We have discovered a significant number of bow shock candi-dates around early-type runaway stars providing a higher quality sample of bow shocks, the E-BOSS sample. For the set, we havedetermined a number of parameters of these objects. We havefound no strong trends concerning the frequency of bow shockswith stellar mass, position, age, velocity, and spectral type.In terms of future work, extending our study to later spectraltypes will allow us to systematically search for and investigateradiative bow shocks (see for example G´asp´ar et al. 2008). Theextensive Tetzla ff et al. (2010) database will also serve as a start-ing point for that study. We will also incorporate in forthcomingE-BOSS versions other runaway databases together with indi-vidual objects from the literature.Detailed studies of individual objects will help us to moreclearly understand the stellar winds of the bow-shock producerstars, the medium in which they travel, and the stellar history,among other things. We plan to continue our studies of individ-ual objects in the E-BOSS sample, as well as statistical studiesof the global sample. Acknowledgements.
C.S. Peri and P.B. are supported by the ANPCyT PICT-2007 / / IPAC Infrared Science Archive, which is operated bythe Jet Propulsion Laboratory, California Institute of Technology, under con-tract with the National Aeronautics and Space Administration, the SIMBADdatabase, operated at CDS, Strasbourg, France, and data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University ofCalifornia, Los Angeles, and the Jet Propulsion Laboratory / California Instituteof Technology, funded by the National Aeronautics and Space Administration.C.S. Peri is grateful to M.V. del Valle for a discussion on theoretical issues. Wealso thank an unknown A&A referee for the comments and suggestions that haveimproved the article.
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Table 1.
Star members of Group 1.
HIP HD / BD / Other Spectral type MSX WISE 19971415 1337 O9IIInn + ... – –2599 2905 / κ Cas B1Iae (cid:63) ⊃ ⊃ (cid:63) • (cid:63) • * (cid:7) ?14514 19374 B1.5V – (cid:63) • (cid:63) (cid:63) ⊃ ?17358 22928 B5III – ⊃ ⊃ × (cid:63) • / α Cam O9.5Iae – ⊃ ⊃ ⊃ • +
39 1328 O9III: × (cid:63) • ——– 36862 / λ Ori B0.5V – [a] ⊃ (cid:12) (cid:12) • × • * (cid:7) ?28881 41161 O8V – ⊃ ⊃ (cid:12) • / δ Pic B3III + ... – ⊃ ⊃ (cid:63) (cid:12) (cid:63) ⊃ ⊃ (cid:63) • • (cid:63) ⊃ ⊃ / τ CMa O9Ib – (cid:12) ⊃ ⊃ (cid:12) • • × – • ——– 92206 O6.5V [b] – • (cid:12) • • • HIP HD / BD Spectral type MSX WISE 199772510 130298 O5 / O6 (cid:63) ⊃ ⊃ • • + ... × ⊃ • / δ Sco B0.2IVe – ⊃ ⊃ / ζ Oph O9V – ⊃ ⊃ + ... (cid:63) (cid:63) † (cid:63) • • † • • * • × • • (cid:63) (cid:12) ⊃ (cid:63) ⊃ ⊃ × ø • ⊃ ⊃ (cid:12) – • • ⊃ – ⊃ ——— +
43 3654 / U824 O4I ⊃ – ⊃ (cid:63) – • • (cid:63) – • / ⊃ • – • / λ Cep O6If(n)p (cid:63) – ⊃ • • ⊃ ?114990 +
63 1964 B0II (cid:63) ⊃ • (cid:63) • Notes.
Stars of group 1 were taken from Noriega Crespo et al. (1997). All were observed by the IRAS satellite and two by the Spitzer-Glimpseprogram ( † ). The first column lists the Hipparcos number of the star; the second one, other identification(s). Column (3) shows the spectralclassification, from the GOSC whenever possible or from NC97 otherwise. Columns (4) and (5) give information about MSX and WISE emissionon the stellar fields, according to the following symbols. (cid:63) : point source on star, ⊃ : bow shock candidate, ⊃ ?: doubtful bow shock candidate, –:stellar field not covered by the survey, × : no star or emission close-by, (cid:12) : extended source on star, • *: confusion with larger structure, ø: di ff useemission, • : emission excess, (cid:7) ?: possible bubble. Column (6) lists the qualifiers (same meaning as before) as in the original work by NC97. [a]The star HD 36862, together with HD 36861 (O8III), belong to a rich cluster, are not single, and have a large spatial velocity. More than onefeature can produce the surrounding IR emission detected. [b] Cappa et al. (2008) studied the environs of HD 92206, and identified an HII region.We discarded these two cases from our sample.6eri et al.: The Extensive stellar BOw Shock Survey Table 2.
Star members of group 2.
HIP Sp.t. HIP Sp.t. HIP Sp.t. HIP Sp.t. HIP Sp.t. HIP Sp.t.278 B2IV 505 O6pe 1805 B0IV
B1V
B1Ia 4532 B1II4983 B2IV-V 5391 B1V 6027 B2III 8725 O8V 9538 B1V 10463 B2IV-V10527 B0.5III 10641 B2Ib 10849 B2V 10974 B2 11099 O8.5V 11279 B2Ia11347 B1Ib 11394 O6 11396 B2 11473 O9.5V 11792 O9V
O512009 B1Iab 12293 B2 13736 B0II-III 13924 O7V 14514 B1.5V 14626 B1V14777 B2 14969 B2IV 15270 B2.5IV-V
B1V 16566 O 17387 B2V18151 B1III 18350 O9.5 18614 O7.5Iab 19218 O8 21626 B2.5V 22061 B2.5V22461 B1II-III 23060 B2V 24072 B2III 24238 B2V
O9.5V
B0V26064 B2IV-V
B0.5V 26889 B0II 27204 B1IV-V 27850 B1V 27941 O628756 B2V 29201 B0V
B0.5IV 29317 B1V 29321 B2V 29563 B2V29678 B1V 30961 B2.5IV-V
O9.5II 31787 B0IV
O6 32300 B0.5IV32602 O6 32947 B2V 33300 B2V 33754 B1Ib
O6 34924 B2III34986 B0.5III 35149 B1.5III 35951 B2V 36369 O6 36778 B2V 37169 O9.5Iab38855 B2V 39172 B2.5V 40047 O5p 44685 B2IV 45880 B2 46760 B2V48715 B1Ib 52670 B2.5V 54572 B2V 58748 B1II 61431 B1Ib
B2V62829 B0.5III 63049 B0IV 63117 O9Ib 63170 B0.5Ia 63256 B2V 64272 B1Ib67663 B2V 68002 B2.5IV-V 68817 B0.5V 69892 O8.5 69996 B2.5IV 70574 B2IV70877 B2III 71264 B2V 72438 B2.5V
O7.5 72710 B2 74778 O8.5V
B2Ib 75141 B1.5IV 75711 B2II / III 76013 B1 76642 B2III 78145 B0.5Ia78582 B2V 79466 B2III 80782 B1.5Iap 80945 B1Ia 81100 O6e 81122 B0Ia81305 O9Ia
O9.5V 81696 O7V
B0Iab 82378 O9.5IV 82691 O7e82775 O8Iab... 82783 O9Ia 83003 O... 83574 B2Iab 83635 B1V 84226 B1Ib84338 B2III 84401 O9 84687 B0V 84745 B2V 85331 O6.5III 85530 B2V85885 B2II 87397 B2III 88004 B1Iab 88496 B2V 88584 O6
O9.5Iab88714 B2Ib 89743 O9.5V 90610 B2V 90804 B2V 90950 B0Ia / Iab 91003 O791049 B2II 91599 B0.5V 92133 B2.4V 93118 O7.5 93796 B1Ib 93934 B2II94934 B2IV 95408 B2V 96130 B1.5III 96362 B2V 97246 B1Ia 97545 B1V97679 B2.5V 117514 B2V3013 B2 38518 B0.5Ib 39429 O8Iaf 39776 B2.5III 40341 B2V 41168 B2IV41463 B2V 41878 B1.5Ib 42316 B1Ib 42354 B2III 43158 B0II / III 43868 B1Ib44251 B2.5V 44368 B0.5Ib 46950 B1.5IV 47868 B0IV 48469 B1V 48527 B2V48730 B2IV-V 48745 B2III 49608 B1III 49934 B2IV 50899 B0Iab / Ib 51624 B1Ib52526 B0Ib 52849 O9V 52898 B2III 54179 B1Iab 54475 O9II 58587 B2IV61958 Op 65388 B2 74368 B0 89902 B2V 94716 B1II-III 97045 B0V97845 B0.5III 98418 O7 98661 B1Iab 99283 B0.5IV 99303 B2.5V 99435 B0.5V99580 O5e 99953 B1V 100088 B1.5V 100142 B2V 100314 B1.5Ia 100409 B1Ib101186 O9.5Ia 101350 B0V 102999 B0IV 103763 B2V 104316 O9 104548 B1V104579 B1V 104814 B0.5V 105186 O8 105912 B2II 106620 B2V 106716 B2V107864 Op 108911 B2Iab 109051 B2.5III 109082 B2V 109311 B1V 109332 B2III109556 B1II 109562 O9Ib 109996 B1II 110025 B2III 110287 B1V 110362 B0.5IV110386 B2IV-V 110662 B1.5IV-V 110817 B0.5Ib 111071 B0IV 112482 B1II 112698 B1V114482 O9.5Iab 114685 O7
Notes.
Top: Stars with
WISE observations (164 stars). Bottom: stars without
WISE observations (80 stars). The spectral types are from Tetzla ff etal. (2010). In bold font: the 17 bow shock candidates detected, see text. 7eri et al.: The Extensive stellar BOw Shock Survey Table 3.
List of the E-BOSS bow shock candidates and corresponding stellar parameters.
Star Group l b
Spectral type d v ∞ ˙ M × v tg v r µ α cos δ µ δ [ ◦ ] [ ◦ ] [pc] [km s − ] [ M (cid:12) yr − ] [km s − ] [km s − ] [mas yr − ] [mas yr − ]HIP 2036 2 120.9137 + + B1V 757 ± a [1200] 0.48 15.2 − − + ± a − − + −
48 0.03 − − < − + ± a − ± a [1200] 0.1 140.0 59.1 − − − + −
19 0.88 − + b − − / < − ± a − − + + ... 2117 ± a + ... 1293 ± a − + + ... ( 900 ) [2570] 0.7 [13] 28 − − − − + − − − + / Ib ( 800 ) [1065] 0.14 28.6 4 − − + − − + ± a [1100] 0.14 [38] − + ± a [1500] 0.02 24.4 −
15 15.26 24.79HIP 82171 2 329.9790 -08.4736 B0.5 Ia 845 ± a − − − + − − + − − c [1980] 0.50 [110] 9 − − + ± a [1735] 0.23 22.3 − − +
43 3654 1 082.4100 + d [2325] 6.5 [14] − − + e [1400] 0.6 [52] − − − Notes.
Galactic coordinates: taken from Simbad. Spectral types: for B-type stars from the Simbad database, for O-type stars GOS Catalog.References for the distance values: (a) Megier et al. (2009), (b) Mason et al. (1998), (c) Schilbach & Roeser (2008), (d) Hanson (2003), (e)Thorburn et al. (2003); distances in brackets: derived from Hipparcos (van Leeuwen 2007) parallaxes. Terminal velocities in square brackets:from Howarth et al. (1997), otherwise inter- or extrapolated from Prinja et al. (1990). Mass-loss rates: derived from Vink et al. (2001). Tangentialvelocities in brackets derived from proper motions (van Leeuwen 2007), otherwise from Tetzla ff et al. (2010). Radial velocities are from theSecond Catalog of Radial Velocities with Astrometric Data (Kharchenko et al. 2007).8eri et al.: The Extensive stellar BOw Shock Survey Table 4.
Observational parameters of the bow shock candidates obtained from the images of MSX and WISE.
Star l w R l w R n
ISM
Comments[arcmin] [pc] [cm − ]HIP 2036 4.5 1.3 1 0.99 0.29 0.22 130 Emission-line starHIP 2599 9 1.3 3 3.81 0.55 1.27 0.4 Emission-line starHIP 11891 4 1 1 1.05 0.26 0.26 3 Star in clusterHIP 16518 4 1 0.7 0.76 0.19 0.13 0.2 Variable starHIP 17358 3 1 1 0.13 0.04 0.04 600 Variable starHIP 22783 33 10 10 15.43 4.67 4.67 0.02 Emission-line starHIP 24575 2 0.5 0.4 0.32 0.08 0.06 3 Double or multiple starHIP 25923 4 1 1.5 1.05 0.26 0.39 1 Variable starHIP 26397 3 1 1 0.31 0.10 0.10 2 StarHIP 28881 9 1.5 3 5.54 0.92 1.85 0.3 Double or multiple starHIP 29276 5 2 2 0.58 0.23 0.23 0.003 Eclipsing binary of beta Lyr typeHIP 31766 5 2 2 2.06 0.82 0.82 0.03 Double or multiple starHIP 32067 13 2.5 3 8.01 1.54 1.85 0.1 Emission-line starHIP 34536 12 3 4 4.51 1.13 1.50 0.01 HII (ionized) regionHIP 38430 2 0.5 0.5 0.52 0.13 0.13 60 Emission-line starHIP 62322 4 1.2 1 0.17 0.05 0.04 0.02 Double or multiple starHIP 72510 4.5 0.8 1.5 0.46 0.08 0.15 0.2 Emission-line starHIP 75095 1.5 0.5 0.5 0.35 0.12 0.12 40 StarHIP 77391 4 1 1 0.93 0.23 0.23 30 StarHIP 78401 25 2 6 1.63 0.13 0.39 2 Double or multiple starHIP 81377 22 2 5 1.42 0.13 0.32 1 Be starHIP 82171 2 0.5 0.7 0.49 0.12 0.17 1 StarHIP 88652 6 1 1.5 1.13 0.19 0.28 2 StarHIP 92865 11 1 3 1.12 0.10 0.31 0.003 Eclipsing binary of beta Lyr typeHIP 97796 13 2.5 6 8.32 1.60 3.84 0.02 Spectroscopic binaryHIP 101186 19 2.5 4 8.21 1.08 1.73 0.1 Emission-line starBD +
43 3654 12 3 3.5 5.06 1.27 1.48 0.2 StarHIP 114990 3.5 0.75 1.5 1.43 0.31 0.61 0.05 Star
Notes.
Columns (2) to (7): length ( l ) and width ( w ) of the bow shock structure, and distance ( R ) from the star to the midpoint of the bow shock, inangular and linear units. Column (8): the ambient density n ISM (see text). The descriptions in the last column are taken from the Simbad database.9eri et al.: The Extensive stellar BOw Shock Survey
RA (J2000) D E C ( J2000 ) HIP 2036
RA (J2000) D E C ( J2000 ) HIP 2599
RA (J2000) D E C ( J2000 ) HIP 11891
RA (J2000) D E C ( J2000 ) HIP 16518
RA (J2000) D E C ( J2000 ) HIP 17358
RA (J2000) D E C ( J2000 ) HIP 22783
Fig. 1.
WISE images of the bow shock candidates around 6 OB stars. Color mapping: blue = green = red = RA (J2000) D E C ( J2000 ) HIP 24575
RA (J2000) D E C ( J2000 ) HIP 25923
RA (J2000) D E C ( J2000 ) HIP 26397
RA (J2000) D E C ( J2000 ) HIP 28881
RA (J2000) D E C ( J2000 ) HIP 29276
RA (J2000) D E C ( J2000 ) HIP 31766
Fig. 2.
Same as in Figure 1, for another six OB stars.
RA (J2000) D E C ( J2000 ) HIP 32067
RA (J2000) D E C ( J2000 ) HIP 34536
RA (J2000) D E C ( J2000 ) HIP 38430
RA (J2000) D E C ( J2000 ) HIP 62322
RA (J2000) D E C ( J2000 ) HIP 72510
RA (J2000) D E C ( J2000 ) HIP 75095
Fig. 3.
Same as in Figs 1-2, for another six OB stars.
RA (J2000) D E C ( J2000 ) HIP 77391
RA (J2000) D E C ( J2000 ) HIP 78401
RA (J2000) D E C ( J2000 ) HIP 81377
RA (J2000) D E C ( J2000 ) HIP 82171
RA (J2000) D E C ( J2000 ) HIP 88652
RA (J2000) D E C ( J2000 ) HIP 92865
Fig. 4.
Same as in Figs 1-3, for another six OB stars.
RA (J2000) D E C ( J2000 ) HIP 97796
RA (J2000) D E C ( J2000 ) HIP 114990
RA (J2000) D E C ( J2000 ) BD +43 3654
RA (J2000) D E C ( J2000 ) HIP 101186
Fig. 5.
WISE images of bow shock candidates as in Figures 1-4, for HIP 97796 and 114990. MSX images for BD + ◦ = = = Spatial distribution (l,b) - Group 1 BS-C (18)No BS-C (30)No data on MSX or WISE (8)
Fig. 6.
Distribution on the (l,b) plane of group-1 stars.
Spatial distribution (l,b) - Group 2 BS-C (17)No BS-C (147)No data on WISE (80)
Fig. 7.
Distribution on the (l,b) plane of group-2 stars. T o t a l : s pe c t r a l t y pe - bo w s ho cks Spectral type Group 1Total bow shocks by spectral typeTotal stars by spectral type
Fig. 8.
Distribution of group-1 stars by spectral types. T o t a l : s pe c t r a l t y pe - bo w s ho cks Spectral typeGroup 2 Total bow shocks by spectral typeTotal stars by spectral type
Fig. 9.
Distribution of group-2 stars by spectral types.
Fig. 10.
Distribution of group-2 stars by stellar mass (5 M (cid:12) bin-ning).
Fig. 11.