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The mysterious Ofp class and the magnetic O-star Theta Ori C

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Revista Mexicana de Astronom′?a y Astrof′?sica ,00,??–??(2008)THE MYSTERIOUS OF?P CLASS AND THE MAGNETIC O-STAR θ1Ori C:CONFRONTING OBSERVATIONS Ya¨e l Naz′e 1Nolan R.Walborn 2and Fabrice Martins 3RESUMEN En a?n os recientes,las estrellas de la categor′?a Of?p han revelado una multitud de fen′o menos peculiares:per?les de l′?neas variables,cambios fotom′e tricos,y exceso de luminosidad en rayos X son solamente algunas de sus caracter′?sticas.Aqu′?repasamos sus propiedades f′?sicas,para facilitar comparaciones entre los miembros Gal′a cticos de esta https://www.sodocs.net/doc/8c16191075.html,o uno de ellos se ha propuesto como semejante al rotador magn′e tico oblicuo θ1Ori C,aunque con un per′?odo m′a s largo,este ′u ltimo objeto est′a tambi′e n inclu′?do en nuestro estudio,para iluminar sus similitudes y diferencias con la categor′?a Of?p.ABSTRACT In recent years,the stars of the Of?p category have revealed a wealth of peculiar phenomena:varying line pro?les,photometric changes,and X-ray over-luminosity are only a few of their characteristics.Here we review their physical properties,to facilitate comparisons among the Galactic members of this class.As one of them has been proposed to resemble the magnetic oblique rotator θ1Ori C,though with a longer period,this latter object is also included in our study to illuminate its similarities and di?erences with the Of?p category.Key Words:Stars:early-type —Stars:individual (HD 108,HD 148937,HD 191612,θ1Ori C)—Stars:variables:other 1.INTRODUCTION In astronomy,the study of peculiar objects often provides crucial information.Indeed,a rare phenomenon could be linked to short-lived phases in the evolution of stars or galaxies.It might thus represent a ‘missing link’in our understanding of the Universe,therefore deserving an in-depth analysis.Though rare,O-type stars are nevertheless important as they are the main sources of ionizing radiation,mechanical energy,and certain chemical elements in galaxies.However,their lifetimes are short (a few million years)and their rapid evolutionary phases are thus very di?cult to study.To better understand these hot,massive objects,it is thus important to probe the properties of the most peculiar ones,such as the Of?p stars.

The Of?p category was de?ned by Walborn (1972,1973)to classify stellar spectra displaying certain pecu-liarities,notably strong C iii emission lines around 4650?A (more details on classi?cation criteria below).At ?rst,only two stars belonged to this category,HD 108and HD 148937,but a third one was soon added,HD 191612(Walborn 1973).A few others have now been identi?ed in the Magellanic Clouds (Heydari-Malayeri &Melnick 1992;Walborn et al.2000;Massey &Du?y 2001;Evans et al.2004).In recent years,these peculiar objects attracted quite a lot of attention because of the discovery of recurrent line-pro?le variations and X-ray over-luminosities.A magnetic ?eld was even reported for HD 191612,making it the second O-type star with a detected magnetic signature -the ?rst one being θ1Ori C (Donati et al.2002;Donati et al.2006).

The aim of this short review is to summarize the properties of the Of?p stars,in the visible,UV,and X-ray domains,and to compare them to those of θ1Ori C,a known magnetic oblique rotator.This paper is

organized

2NAZ′E,WALBORN,&MARTINS

Fig.1.Variations over the15d period of the spectra ofθ1Ori C(left,?gure from Stahl et al.1996)and evolution of the red spectrum of HD108between1997and2003(right,?gure from Naz′e et al.2004).

as follows.Section2describes the main properties derived from the UV/visible spectra of these stars,Section 3presents their photometric characteristics,Section4describes their observations in the X-ray domain,and Section5gives our conclusions.

2.VISIBLE AND UV SPECTRUM

The study of O-type stars has long focused on the UV/visible spectra of these objects.Indeed,a wealth of information can be derived from them.To cite only a few:lines varying in position indicate binarity;relative line strengths indicate temperature;and emission-line pro?le variations relate to peculiar phenomena such as transient wind inhomogeneities,wind-wind collisions,or a disk con?ned by an oblique magnetic?eld.We present here the properties derived from the spectra of the Of?p stars and ofθ1Ori C.

2.1.Spectral Type

Thoughθ1Ori C is often studied,its spectral classi?cation is still under debate.It is generally considered to be O7V(Stahl et al.2008),but Walborn(1981)found a changing spectral type,which remains to be con?rmed.In the context of this review,it is important to note the absence of strong C iiiλ4650in emission, which is one of the main characteristics de?ning Of?p stars.

The f?p designation should only be added when several spectral criteria are ful?lled.The most important one is of course the presence of a strong C iiiλ4650emission,i.e.of an intensity comparable to that of the neighboring N iii lines.Additional features are common amongst Galactic Of?p stars:composite pro?les for the Balmer hydrogen lines,with a narrow P Cygni/emission component superimposed on a broad(photospheric) absorption;P Cygni He i pro?le or asymmetric He i lines,with the red wing being steeper than the blue one; other peculiarities such as weak Si ivλλ1393,1402wind pro?les unlike for Of supergiants,and,in some cases, the Si iiiλλ4552,4568,4575triplet in emission.

Comparing the He i to He ii absorption lines,HD148937appears rather early,with a type O5.5-6f?p (Naz′e et al.2008),but the cases of HD108and HD191612seem more complex.In fact,the spectral types of these two stars are not constant:using the classical He i-He ii indicators,they alternate between O4and O8.5 for HD108(Naz′e et al.2001,2004),or O6.5and O8for HD191612(Howarth et al.2007).As the C iiiλ4650 emission is only present when these stars appear very early,the f?p designation is only added in this case, whereas the fp classi?cation is su?cient when the spectral type is the latest4.

2.2.Line Pro?le Variability

Hints at spectral changes inθ1Ori C were already reported by Conti(1972).The variability was fur-ther studied by Walborn(1981);Stahl et al.(1993);Walborn&Nichols(1994);Stahl et al.(1996,2008).The largest variations are observed for the Balmer hydrogen and He iiλ4686lines(Fig.1).However,the equivalent widths(EWs)of other lines,e.g.the photospheric lines of He iλ4471,He iiλ4542,O iiiλ5592,C ivλ5801, appear to change in harmony with those of H and He iiλ4686,though with a smaller amplitude(15%change vs100%)and with an opposite behaviour(maximum absorption when maximum emission is seen for H lines).Clear line pro?le variability was also found in the UV range for the Si ivλλ1393,1402,C ivλλ1548,1550 O vλ1371N ivλ1718lines,which display a maximum absorption when the H lines present a maximum emis-sion(Walborn&Nichols1994;Stahl et al.1996).In addition,Walborn(1981)mentioned variations of the He iλ4471/He iiλ4542ratio,but this was not observed in subsequent studies(see e.g.Stahl et al.1996,2008).

Among the Of?p stars,HD108has been the most studied,but con?icting results about its nature were reported:a short-period binary(Hutchings1975;Aslanov&Barannikov1989,the system having even survived a supernova event according to Bekenstein1976);a single star experiencing wind variability and/or harboring a

CONFRONTING OBSERVATIONS OF OF?P STARS ANDθ1Ori C3 Fig. 2.Evolution of the equivalent widths of

He iλ4471(crosses),He iiλ4542(?lled circles), and Hβ(open triangles)in the spectrum of HD108(?gure from Naz′e et al.2006).Fig.3.Phase-locked variations inθ1Ori C of the equivalent width of Hα.(?gure from Stahl et al.1996).

Fig.3.Continued.Phase-locked variations inθ1Ori C of the equivalent width of He iiλ4686(left).On the right are shown the normalized and phase-averaged variations of the equivalent widths of He iλ4471,He iiλ4542,O iiiλ5592, and C ivλ5801(?gures from Stahl et al.1996).

disc and jets(Vreux&Conti1979;Underhill1994);or a long-period(a few years)binary(Barannikov1999)... To attempt to resolve the confusing situation,a30-year spectroscopic campaign was undertaken at the Haute-Provence Observatory(Naz′e et al.2001).A detailed analysis of the data allowed most of the older models to be discarded and rather unveiled a peculiar phenomemon:dramatic line-pro?le variations on a timescale of decades(Figs.1and2;for the?rst hints of the phenomenon see also Andrillat et al.1973).The Balmer hydrogen and He i lines change from strong P Cygni pro?les to pure absorptions with asymmetric pro?les.A few other emission lines were also found to be strongly variable(C iiiλ4650,He iiλ4686).

Walborn et al.(2003)investigated another Of?p star,HD191612,and discovered similar line pro?le varia-tions.The changes apparently come from a varying narrow emission,slightly redshifted,superimposed on the ‘normal’stellar lines.It should,however,be noted that not all lines are varying:He iiλ4200,4542,O iiiλ5592, C iiiλ5696,C ivλ5812,...(all most probably of photospheric origin)appear relatively constant in strength (Naz′e et al.2001;Howarth et al.2007).Therefore,since variability a?ects He iλ4471but not He iiλ4542, apparent spectral-type variations,measured from the He i/He ii ratio,are detected,as noted above.Note that these changes have a long-term character,but small-scale,short-term variations are also observed for HD191612 as well as HD108(Howarth et al.2007;Naz′e et al.2008).In the remainder of the paper,we de?ne the‘qui-escent’state as the time when the contamination by excess emission is minimum,i.e.when the spectral type appears to be the latest.

Only little was known about HD148937until recently,when we undertook a spectroscopic campaign with the SMARTS program at the CTIO1.5m telescope.This monitoring revealed low-level variability in the Balmer and He iiλ4686lines,but constancy for He i,C iiiλ4650,and other lines(Naz′e et al.2008).Note that if this variability were similar in nature to that of HD108and HD191612,though with a much lower intensity,we would expect no detectable variations of the He i and C iii,as the hydrogen changes are the largest of all lines for these stars.

Because of the lack of high-quality data,the UV spectrum of the Of?p stars was only little investigated up to now-though the few IUE data available,shown in?gure1of Walborn et al.(2003),were of course used for model atmosphere?ts(see Section2.4).The only signi?cant result is the lack of strong variability between the two IUE spectra corresponding at the two extreme states of HD191612(data unfortunately taken with two di?erent spectral resolutions,see Howarth et al.2007).However,since these stars are highly variable,one still needs to be cautious before drawing conclusions from such a limited dataset.Additional observations are thus needed to undertake an in-depth analysis,similar to what has been done forθ1Ori C.

2.2.1.Periodicity

The EW changes ofθ1Ori C are recurrent with a very stable period of15.424±0.001d(Fig.3,see also Stahl et al.2008),while those of HD191612display a period of537.6±0.4d(Walborn et al.2004;Howarth et al. 2007).Comparing all the available data,the changes observed in HD108also appear repeatable,on a timescale of a few decades(approximately50–60years,see Naz′e et al.2001,2006)5.Finally,the line pro?le variations of Hαin HD148937present a possible periodicity of7.031±0.003d(Naz′e et al.

2008).

4NAZ′E,WALBORN,&MARTINS

2.3.Binarity

Long-term radial velocity changes,a typical signature of binary motion,were reported forθ1Ori C by Stahl et al.(1993,see also summary in O’Dell2001)and for HD191612by Naz′e et al.(2007).Subsequent studies have provided more detailed orbital parameters.θ1Ori C is actually a visual binary and a?rst analysis of interferometric measurements yields a period of10.9yr,an eccentricity of0.9,and a mass ratio of0.45±0.15, suggesting the component spectral types to be O5.5+O9.5,and the masses34+15.5M⊙(Kraus et al.2007). These parameters were recently revised by Patience et al.(2008)who proposed a longer period(about26yrs) and a much smaller eccentricity(e=0.16±0.14)but the authors caution that the results are still preliminary since less than half the orbit has actually been observed.Radial velocities analyzed by Stahl et al.(2008)are consistent with the interferometric measurements,but do not permit to discriminate between both solutions. It should also be noted that rapid radial velocity changes are also detected but they seem uncorrelated with the 15d timescale of the line pro?le variability(Stahl et al.2008).On the other hand,the radial velocity curve of HD191612shows that P=1542±14d,e=0.44±0.04,and M2/M1=0.48±0.04—the system thus probably contains an O8+early-B star(30+15M⊙,Howarth et al.2007).

The multiplicity of the other two Of?p objects is less clear.Though HD108was repeatedly suggested to be a binary in the past(Hutchings1975;Aslanov&Barannikov1989;Barannikov1999),recent monitoring could discard the proposed solutions and all periods from a few days to a few years(Naz′e et al.2001).However, radial-velocity changes are detected for HD108(between?55and?85km s?1,Naz′e2004;Naz′e et al.2006), and a very long-term binary cannot be excluded.HD148937displays no radial-velocity changes of amplitude larger than10km s?1on short or long timescales(Conti et al.1977;Garmany et al.1980;Naz′e et al.2008), but low-amplitude variations or very long-term changes are not excluded by the available data.

2.4.Physical Parameters

The spectrum ofθ1Ori C was modeled in detail by Sim′o n-D′?az et al.(2006)and Kraus et al.(2007);their results are reproduced in Table1,with only one modi?cation.In fact,the distance to the Orion Nebula was recently revised by Menten et al.(2007)to414pc(instead of the usual450pc,used notably by Sim′o n-D′?az et al. 2006,or434pc of Kraus et al.2007).The luminosity ofθ1Ori C appearing in Table1was thus changed accordingly,as well as the stellar radius,assuming the e?ective temperature is not changed,which is a fair approximation.

We estimated the projected rotational velocity of the Of?p objects by applying the Fourier method(see Sim′o n-D′?az&Herrero2007,and references therein)to uncontaminated,‘photospheric’lines(e.g.C ivλ5812 and O iiiλ5592).This method was also the one chosen by Sim′o n-D′?az et al.(2006),thus enabling a direct comparison between the stars.It might be noted that these new values are lower than previous estimates because the Fourier method can disentangle the di?erent contributions to the line broadening(Sim′o n-D′?az&Herrero 2007).Model-atmosphere?ts further provided the e?ective temperatures,gravities,and luminosities of the Of?p stars in the quiescent state(Howarth et al.2007for HD191612,Naz′e et al.2008for HD148937,and this work for HD108,see also Fig.4).The results are reported in Table1).The best-?t gravity values clearly suggest that these stars are not supergiants,as was once proposed,but giants or main-sequence objects.

Fig.5presents the positions of the stars in the HR diagram:two stars are close together,suggesting that they share similar properties,whereas HD148937appears clearly more massive and more luminous and θ1Ori C appears only slightly less massive and less luminous.Note that for the luminosity estimates,the distances to the Of?p stars are based on their supposed membership in OB associations(2.51kpc,Cas OB5 for HD108;2.29kpc,Cyg OB3for HD191612;and1.38kpc,Ara OB1a for HD148937,see Humphreys1978), which may be uncertain.

The masses were estimated by several methods:orbital solutions for binary objects,model-atmosphere?ts (M spec=gR2/G),and positions in the HR diagram compared to predictions of evolutionary models.The values derived by the?rst and last methods are listed in Table1,with a superscript indicating the method used.The di?erent determinations generally coincide very closely for a given star,except for HD148937where the HR-diagram mass is at1σfrom the spectroscopic mass(82±33M⊙),but still within the error bar.

The ages of the stars were estimated by comparing their positions in the HR diagram to theoretical isochrones,which yields2–4Myr for the Of?p objects and~1Myr forθ1Ori C.The ages of the associa-tions to which the stars belong generally provide a more accurate estimate.For our objects,this method

CONFRONTING OBSERVATIONS OF OF?P STARS ANDθ1Ori C5

https://www.sodocs.net/doc/8c16191075.html,parison of the optical and UV spectrum of HD108(solid black line)and the best?t CMFGEN model (dash-dot red line,see Table1for parameters;note that the?t also yields˙M=1–3×10?7M⊙yr?1for a clumping factor f=0.01).The narrow emission components in the He i and H optical lines are not?tted and are most probably of circumstellar origin(disk?).This?gure only appears in colors in the electronic version of the journal..

yields<1–2Myr forθ1Ori C(Hillenbrand1997),2–5Myr for HD191612(Massey et al.1995),and0–3Myr for HD148937(Vazquez&Feinstein1992).θ1Ori C seems to be the youngest system of the sample,in agreement with its location in the Orion Nebula Cluster,but the uncertainties on the ages of the Of?p objects make a more detailed comparison di?cult.

2.4.1.Evolutionary Status:Peculiar Abundances and Circumstellar Material

Model atmosphere?ts are also able to reveal the abudance pattern.For HD108and HD148937,they unveil a clear overabundance of nitrogen:for HD108,N/H is6×10?4,i.e.a value about9times solar(this work) while it is3×10?4,or about4times the solar value,for HD148937(Naz′e et al.2008).A comparison of line strengths in the spectra of the Of?p stars suggests a similar overabundance for HD191612.This enrichment, together with the presence of common spectral features,points towards similarities between the Of?p stars and Ofpe/WN9objects(Walborn et al.2003),suggesting that these stars might be slightly evolved objects.

In this context,it is interesting to note that HD148937is surrounded by a circumstellar nebula:the bipolar nebula NGC6164-6165.The northwest lobe,NGC6164,is receding while the southeast lobe,NGC6165, is approaching;this suggests an expansion,with a projected velocity of30km s?1(Leitherer&Chavarria-K. 1987).Moreover,the nebula displays anomalous chemical abundances,and it was therefore suggested to have been formed through an eruption of the Of?p central star(Leitherer&Chavarria-K.1987;Dufour et al.1988). Evidence of this process can be found in the similar nitrogen overabundances of the nebular and stellar data (factor of4–5compared to the solar value;Dufour et al.1988;Naz′e et al.2008).It is possible that the lower amplitude of the line-pro?le variability for HD148937arises from a relaxation of the system following a Luminous-Blue-Variable-like eruption.

3.PHOTOMETRIC VARIABILITY

Hipparcos broad-band photometry of HD191612exhibits a clear modulation with a period of~538d (Koen&Eyer2002;Naz′e2004).The spectroscopic and photometric variations are clearly in phase:when

CONFRONTING OBSERVATIONS OF OF?P STARS AND θ1Ori C

7

Fig.5.HR

diagram with Geneva isochrones and evolu-tionary tracks from Meynet &Maeder (2005).-1.34-1.36

-1.38

-1.4-1.42HJD - 2 400 000 210-1

-2-0.6-0.4-0.200.20.40.6

20-2

-4-0.6-0.4-0.2

00.20.40.6

7.92

7.97.887.867.84

Fig.6.Photometric and EW changes of HD 108(left,data from Naz′e et al.2006and Barannikov 2007)and HD 191612(right,data from Hipparcos archives and

Naz′e et al.2007).Negative EWs correspond to emis-

sion features.

the emission lines are weakest and the star displays an O8spectral type,the star is fainter;when the emissions are maximum and the spectral type is earlier,then the star is brighter (Walborn et al.2004).

Variable photometry was also reported for HD 108(Barannikov 1999,2007).In fact,the brightness of the star clearly decreased in recent years (?V=0.06mag).No signi?cant color variation was found,but the declining luminosity clearly correlates with stronger He i absorptions and weaker H emission lines in the visible spectrum of the star:the photometric variability of HD 108and HD 191612thus appears very similar (Fig.6).As HD 108,HD 148937was included in the “New Catalogue of Suspected Variable Stars”(Kukarkin et al.1981)but its variability status is actually not ascertained.On the one hand,short-term variability was observed by Balona (1992):the star dimmed by 0.01mag over a few weeks.On the other hand,van Genderen et al.(1989)consider the star to have a constant luminosity in V ,though with possible color changes (~0.002mag);a larger dispersion of the magnitude might have been observed during some observing runs.The same authors further suggested that HD 148937might have been bluer and brighter in the late eighties than in 1960.Finally,HD 148937was classi?ed as a possible candidate S Dor variable,but with only weak indications for that status (van Genderen 2001).

No thorough photometric variability analysis has been made for θ1Ori C.However,it is also included in the “New Catalogue of Suspected Variable Stars”(Kukarkin et al.1981)and Hipparcos data display some (appar-ently)stochastic variability with an amplitude of about 0.14mag (between 4.56and 4.70mag,Perryman &ESA 1997).Sim′o n-D′?az et al.(2006)suggested that the 15d variability of the ‘photospheric’-line EWs could be ex-plained by dilution by a varying continuum.However,other scenarios have been proposed:excess absorption due to corotating clouds when the star is seen pole-on (Stahl et al.1996),or excess emission due to infalling material when the star is seen equator-on (Smith &Fullerton 2005;Wade et al.2006).Photometric changes linked to the 15d period thus remain to be identi?ed.

4.X-RAY PROPERTIES

Several high-resolution X-ray spectra of θ1Ori C were obtained with the Chandra Observatory (Schulz et al.2000;Gagn′e et al.2005).These data revealed that θ1Ori C displays a very hard X-ray spectrum,with a clear overluminosity (log[L X /L BOL ]=?6.0,to be compared with the ‘canonical’value of ?6.9from Sana et al.2006).The spectrum is mainly thermal in nature,with two components of temperatures 0.7keV and 2.5–3keV

8NAZ′E,WALBORN,&MARTINS

Fig.7.Di?erential Emission Measure ofθ1Ori C(left,from Zhekov&Palla2007)and HD191612(right,from Naz′e et al.2007).

(Gagn′e et al.2005).The hottest plasma clearly dominates the spectrum(Fig.7).In addition,the X-ray lines appear very narrow(FWHM~600km s?1,i.e.much less than the wind terminal velocity),as expected for a magnetic oblique rotator model(Babel&Montmerle1997;Gagn′e et al.2005).Finally,the X-ray emission is not constant,but varies in phase with the H line emissions of the visible spectrum.

The XMM-Newton observations of Of?p stars detected large overluminosities(log[L X/L BOL]=?6.0to ?6.2),but they also unveiled crucial di?erences fromθ1Ori C(Naz′e et al.2004,2007,2008).First,the X-ray spectra of the Of?p objects are rather soft.In the best?ts,two temperatures are found but the lower one (0.2–0.3keV)clearly dominates(Fig.7).In fact,the component at higher temperature(1–3keV)accounts for only30%of the unabsorbed?ux:it can thus not explain the overluminosity by itself.Second,the X-ray lines are rather broad(FWHM~1800km s?1,a value similar to the wind terminal velocity),as is found for‘normal’O-type stars.

An intriguing characteristic of HD191612must be noted:as forθ1Ori C,its X-ray?ux decreased(by40%) as the emission lines declined in the visible spectrum.However,since all observations were taken during the same538d cycle,it is not yet known whether this variability is phase-locked and if so,with which period(the period of the binary,1542d,or the period of the line pro?le variations,538d).

5.MAGNETIC OBSERVATIONS

Donati et al.(2002)and Donati et al.(2006)reported the detection of magnetic?elds inθ1Ori C and HD191612,respectively,through the analysis of the Zeeman signature in several lines of the visible spectrum. With multiple observations of this signature throughout the15d cycle,it clearly seems thatθ1Ori C is indeed a magnetic oblique rotator as had been suggested before.In this model,the modulation observed in the visible and X-ray domains comes from the viewing angle of the magnetically con?ned disk,which changes with the stellar rotation,i.e.stronger emissions are detected when the disk is seen face-on(for a more detailed modeling see Smith&Fullerton2005).Donati et al.(2006)then proposed HD191612to be an evolved version ofθ1Ori C. In this case,the538d timescale would be the rotation period of the star,which would have been braked as a result of the intense magnetic?https://www.sodocs.net/doc/8c16191075.html,ing also spectropolarimetric data,Hubrig et al.(2008)recently reported the detection of a magnetic?eld for HD148937.Additional spectropolarimetric measurements of HD191612 and HD148937are now needed to check if the observed magnetic?eld follows the phase-locked evolution expected for magnetic oblique rotators.

6.SUMMARY AND CONCLUSIONS

The unusual Of?p stars andθ1Ori C share several similarities but display also intriguing di?erences(see Table2).

In the visible domain,typical lines of O-type spectra,several being in emission or having P Cygni pro?les, are observed for all stars,but the Of?p stars present a rare feature in addition:strong C iiiλ4650emission, the exact origin of which is still unknown.Spectral variability is detected for all objects,but the details vary from one case to another.The common characteristic is the presence of variations of the H and He iiλ4686 lines.The He i and C iii lines also show large pro?le changes,but only for HD108and HD191612;forθ1Ori C, photospheric lines also vary,but at a low level,which might be due to variations in the continuum level;and the observed variability of HD148937has the lowest intensity of all.These line-pro?le variations appear recurrent in each case,but with very di?erent timescales:7d for HD148937,15d forθ1Ori C,538d for HD191612,and 55yr for HD108.These periods are apparently not linked to orbital motion:the two known binaries(HD191612 andθ1Ori C)present much longer orbital periods.However,the periods are related to changes seen in X-rays (forθ1Ori C and possibly HD191612)or in broad-band photometry(for HD191612and HD108).For the latter two objects,the spectral type appears earlier(due to?lling in of the He i lines)when the brightness is greater and the emission lines stronger.

The physical parameters are also quite similar(Table1):low projected rotational velocities,temperatures of about40kK,radii and gravities favoring a main-sequence or giant classi?cation.However,the more massive

CONFRONTING OBSERVATIONS OF OF?P STARS ANDθ1Ori C9

TABLE2

COMPARISON OF THE PROPERTIES OFθ1Ori C AND THE OF?P STARS.

Sp.Type O7V O4f?p?O8.5fp O5.5–6f?p O6.5f?pe?O8fp

HI var var var var

He i var var cst var

He iiλ4686var var var var

C iiiλ4650not pr.var cst var

Line prof.Period15d55yr7d538d

Binary Period11–26yr N?N?1542d

Magn.Field Y?Y Y

N enrichment N Y Y Y

Photometry var?L↓when H↓cst?L↓when H↓

X-ray excess Y Y Y Y

X-ray prop.hard,narrow soft,broad lines

10NAZ′E,WALBORN,&MARTINS

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男装话术很经典很实用

男装话术很经典很实用 Company number【1089WT-1898YT-1W8CB-9UUT-92108】

服务篇 1、你们是什么牌子 答:xxxxxxx,xxx品牌。就是给您这样时尚、有品味的男士穿的。 2、你们这个牌子是刚出来的吧,我怎么从来没有听说过啊 答:您好,我做这个牌子之前也没听过,我们在全国已经有xxx多家了,像你经常到外面去肯定有看到过,可能没注意吧! 3、我VIP卡忘带了能打折吗 答:可以,请您报一下姓名或手机号,身份证号码也可以! 4、过了活动期限仍要求优惠的顾客 答:不好意思,公司有明确规定,我没有权利帮您打折,不过您买我们的衣服一定物有所值(转移话题:款式、品牌、舒适)。 5. 好、就算不打折吧,那你把那个(非赠品)……..送给我 答:不好意思,这是正价商品我没有权利送,都老顾客了!我送您xxx(指定赠品),您就别再难为我了! 6、打折的衣服会不会有质量问题,是不是老款 答:您放心,不会的,我们是为了回馈新老顾客,才会做促销的,平时我们是不打折,您运气好,刚碰上。

7、我很喜欢这件衣服,但没带钱怎么办 答:您好,我们可以刷卡,也可以先预付一部分订金,帮您留到明天下班。 8、你们店铺的款式怎么这么少,都找不到合适我的 答:先生,您好!您可能没有时间仔细看,我们很熟悉店里的货品,您喜欢什么风格我可以帮您挑选到满意的。 9、这件怎么看起来像老款 答:先生,您是我们的老顾客吧,您真有眼光,这是我们的经典款延续,反响都非常好。 10、这款式都是这么年轻的,我穿合适吗(顾客针对导购的推荐时) 答:当然啦,您本来就很年轻,如果穿上它您会更有魅力(针对中年人)。 11、你们的款式怎么越来越年轻了,都找不到适合我穿的 答:生活好了,都要越活越年轻;再说了您本来就年轻,又有活力,所以现在的款式、风格还是非常适合您的。 12、这件男装的款式、颜色还不错,可惜面料不太喜欢 答:您好,这种男装款式的衣服肯定要…….(面料的优点和设计特点),所以这种款还就得采用这种面料。 13、你看这两件衣服,哪一件更好

男装分类设计

礼服概述礼服是指出席正式场合、符合特定礼仪穿的服饰总称,17世纪英国查里斯二世将当时的波斯风格引入了男性服装,确立了外衣、马甲、马裤三件套服式,为现代男性礼服奠定了基础。大体上,礼服都采用燕尾服制式,其衣摆由前至后呈一个大弧状结构,前短后长,单排一个扣,后片开衩,造型宛如燕尾而得名。礼服分类晨礼服属燕尾服结构,只是前片由前向后基本裁成斜线,而非弧线,领型为枪驳领或平驳领,面料为黑色或灰色呢料,胸前手巾袋露出白色麻或绢质手帕马甲通常采用与上衣同面料,夏天用白色面料,双排六粒扣,枪驳领型,衣长至腰间衬衫前片饰褶裥,袖口钮多为纯金,宝石或珍珠,搭配蝉型领结,或为黑白斜纹或银灰色领带。礼服分类晚礼服是按国际惯例只能在下午六点以后穿着的礼服,是男装中的第一礼服,用于最正式场合正规燕尾服样式:双排六钮式设计(左右各三,一般不扣住),枪驳领或丝瓜领,领面用缎料,衣料为高档黑色呢料,衣下摆呈弧线状裁剪,前胸口袋插有白色手帕。搭配同质料马甲,白色礼服衬衫加有U型胸衬,配白色蝴蝶领结,手套为白色小山羊皮,鞋子是黑色漆皮牛津型。西装概述现代西装由17世纪普鲁士士兵军服演变而来的,设计风格多样,驳领、插花眼、手巾袋、开衩、口袋等都演变为装饰设计细节,通过不同组合设计产生不同风格。西装分类传统型西装一般常见为平驳领单排扣上衣,可单粒、双粒、三粒、四粒,另一种常见形式为枪驳领双排扣,有双粒、四粒、六粒几种面料与色彩选择都十分正统,以黑、深藏蓝、黑灰等色居

多,面料多为毛呢混纺,内里十分考究,备多个口袋,风格保守,只在细部变化,如兜型、领型和外轮廓造型。西装分类休闲运动型西装是在传统西服的基础上演化而来的,更突出男性曲线,强调舒适性和时尚性的结合适合在非正式场合穿着,是一种较为轻松方便的生活装,在设计上,大胆使用新面料,新工艺,如水洗工艺,符合现代人的生活习惯西装分类前卫型西装在设计上打破传统西装的固有模式,从外形、色彩、面料到细节处理都有耳目一新的感觉轮廓可以很修长,也可是窄身合体,甚至是紧裹的,适合中性化风潮款式上驳领造型丰富,贴袋、缉线比较活泼,内里面料图案,轮廓用尽心思面料突破传统与正规,可拼接,焕然一新色彩也不是黑白一统天下,可使用鲜艳色彩夹克衫概述原意指前开襟上衣的一种,茄克典型的基本廓型是宽肩的倒梯型服装,有克夫并收缩下摆,在功能上防风防雨,穿脱方便随意,衣长大致到臀部,设计概念随意、轻松夹克衫分类运动型夹克面料选择上比较注意防水、防风、透气性,具代表性的为连帽茄克,插肩袖设计为活动提供方便,同时克夫和下摆处加入橡筋、罗纹或是可调按钮,适合不同体形色彩上比较轻松随意,可以衣领、袖口、手臂两侧等局部加入鲜艳跳跃色彩,增强运动兴奋感。茄克衫分类便式茄克即日常普通型茄克,造型比较简洁、长度较短、松度较大、便于活动。在领型设计上更为随意方便,不仅有小立领、八字领、驳折领,还有连帽式门襟内层拉链、外层钮扣的形式非常普遍茄克衫分类休闲茄克在保留茄克基本外型的基础上更加大胆随意而富有创造性。设计主

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