Accepted by AJ

SPECTROSCOPIC PRE-MAIN SEQUENCE BINARIES

II. HARO 1-14c AND PARENAGO 2494

Bo Reipurth1, Harri Lindgren2, Michel Mayor3,Jean-Claude Mermilliod4, and Noel Cramer3

1: Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822(reipurth@ifa.hawaii.edu)

2: Lund Observatory, Box 43, S-221 00 Lund, Sweden

3: Observatoire de Geneve, CH-1290 Sauverny, Switzerland

4: Institut d’Astronomie de l’Universite de Lausanne,CH-1290 Chavannes-des-Bois, Switzerland

ABSTRACT

In the course of a long-term radial velocity survey of about 100 southern pre-mainsequence stars, we have discovered two spectroscopic pre-main sequence binaries. Oneis the weak-lined T Tauri star Haro 1-14c in the Ophiuchus clouds, which has a spectraltype of K3 and is a member of the visual Haro 1-14 binary with a separation of 12.9arcseconds. Haro 1-14c is a single-lined spectroscopic binary with a very long periodof 591 days. The other is Parenago 2494, a weak lined T Tauri star with a spectraltype of K0 located in the Orion cluster. It is a double-lined spectroscopic binary with aperiod of 19.5 days. Our photometric monitoring shows that P2494 is a low-amplitudevariable with a period of 5.77 days. We have determined accurate orbital elements forboth binaries. We further discuss 5 low-amplitude velocity variable stars, which arepossibly additional spectroscopic PMS binaries.

Subject headings: binaries: spectroscopic — stars: pre-main sequence — stars: vari-ables: other

1. INTRODUCTION

From the earliest studies of T Tauri stars, it was recognized that visual pairs existed amongthem. Joy & van Biesbrock (1944) noted several such pairs, Herbig (1962) listed 29 double starswith at least one T Tauri component, Cohen & Kuhi (1979) added another 9 binaries, and Reipurth& Zinnecker (1993) listed 87 visual pre-main sequence (PMS) binaries. The frequency distribution

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as a function of period for main sequence solar type stars has been derived by Duquennoy & Mayor(1991), and when compared with various surveys of PMS binaries it has been found that the binaryfrequency is at least as high among young PMS stars as it is on the main sequence (e.g. Reipurth& Zinnecker 1993, Leinert et al. 1993, Ghez et al. 1993).

A variety of observational techniques have been brought to bear in searches for PMS bina-ries. At present, only spectroscopic techniques can detect the shortest period PMS binaries forwhich full orbital solutions can be derived. The detection and study of such binaries is of greatimportance, because when orbital parameters are determined, a range of physical problems relatedto the formation and evolution of binary stars can be pursued. Among the issues currently beingdebated are orbital evolution and circularization, the role of circumstellar and circumbinary disksin the evolution of binary parameters, the possibility of using dynamical masses and other compo-nent parameters for an empirical calibration of PMS evolutionary tracks, and insight into binaryformation scenarios (see Mathieu 1994 for a review, and the proceedings of IAU Symposium No.200 - Zinnecker & Mathieu 2001).

The first spectroscopic PMS binary, V826 Tau, was discovered serendipitiously by Mundt etal. (1983), and analyzed in more detail by Reipurth et al. (1990) [Paper I]. The first systematicsurvey aimed at finding spectroscopic PMS binaries was carried out by Mathieu et al. (1989),who found 8 new cases. By now, a considerable number (>30) of low-mass spectroscopic binariesare known, plus a few higher-mass systems (containing B stars), and further surveys are in theprocess of uncovering many more (e.g. Covino et al. 2001; Guenther et al. 2001). Two eclipsingPMS binaries, TY CrA and EK Cep, are known which contain at least one higher-mass component(e.g. Vaz 2001; Popper 1987), and recently the first bona fide low mass eclipsing PMS binary wasdiscovered (Covino et al. 2000).

We have during the years 1989 to 1995 carried out a systematic radial velocity survey of morethan one hundred young low-mass stars in mostly southern star forming regions. The coverage isvery uneven and for individual objects the number of observations range from a few to many dozens.A number of velocity variable stars were identified, but only two new bona fide spectroscopic PMSbinaries were discovered, namely Parenago 2494 in Orion and Haro 1-14c in Ophiuchus. This isless than one would have expected from a similar sample of late-type evolved stars (e.g. Latham etal. 2002), and is likely due to the complex line profiles of T Tauri stars. In this paper we discussthe orbital parameters which we have derived for these two systems.

2. OBSERVATIONS

Radial velocity observations were made with the photoelectric scanner CORAVEL (Baranneet al. 1979, Mayor 1985), attached to the 1.5m Danish Ritchey-Chretien telescope at the EuropeanSouthern Observatory, Chile. The CORAVEL determines a radial velocity by cross-correlationbetween the stellar spectrum and a mask, which selects 1500 metallic lines in the 3600-5200 A

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region. A total of 56 observations were made of Haro 1-14c between June 9, 1989 and July 20, 1995,with typical exposure times of between 30 to 80 minutes. For P2494 a total also of 56 observationswere made between Jan 27, 1984 and May 1, 1991, with typical integration times of 10-15 minutes.Positions for these two stars are listed in Table 1. Furthermore, a total of 24 observations weremade of P2445 (discussed in the Appendix) between Jan 27, 1984 and Mar 4, 1989, with typicalintegration times of 15 minutes. The radial velocity measurements were analyzed with the codein use at the Observatoire de Geneve. In deriving a solution, the individual observations wereweighted by the inverse of the error squared of each velocity. Preliminary results for these starswere announced by Reipurth et al. (2000).

3. THE LONG PERIOD SPECTROSCOPIC BINARY HARO 1-14C

3.1. The pre-main sequence nature of Haro 1-14c

In an Hα emission star survey of the Ophiuchus dark clouds, Haro (1949) found the brightHα emission star now known as Haro 1-14 (= HBC 267 = V2252 Oph = WSB 69). Cohen &Kuhi (1979) list its Hα equivalent width as 45 A. The star is located at the edge of a well-definedhigh-extinction cloud filament (Fig. 1, see also Fig. 1d of Wilking, Schwartz, & Blackwell 1987,their star 69). In Fig. 2a we present a low-dispersion spectrum of Haro 1-14, which shows Hα,Hβ and Hγ in emission, a prominent Sodium doublet in absorption, the MgH band and weak TiObands. This is consistent with the spectral type of M0 suggested by Cohen & Kuhi (1979) basedon their low-dispersion spectrum. Berdnikov et al. (1991) found Haro 1-14 to vary between 13.90< V < 14.16 and established a well-determined period of 8.21 days, presumably due to rotationalmodulation from star spots. Ghez et al. (1993) and Aspin et al. (1997) used active optics techniquesto exclude that Haro 1-14 has a sub-arcsecond infrared companion at separations larger than 0.1arcsecond.

Herbig & Bell (1988) note that Haro 1-14 is the fainter component (to the east-south-east) of adouble star with about 12.9 arcsec separation (Fig.1). The brighter component, now known as Haro1-14c (= HBC 644) was observed spectroscopically by Rydgren, Strom, & Strom (1976), and theynoted that the broad Ca II H and K absorption features show emission cores. On this basis theysuggested that Haro 1-14c is also a young star, and that it forms a physical pair with the fainterT Tauri star Haro 1-14. Both stars are enveloped in faint reflection nebulosity. Berdnikov et al.(1991) found the star (which they call Haro 1-14a) to be irregularly variable within the range 12.49< V < 13.13. In Fig. 2b we present a low-dispersion spectrum of Haro 1-14c, which shows a veryweak, almost non-detectable emission at Hα, and no other emission lines. The Sodium absorptionline is prominent as is the MgH band, consistent with the spectral type of K3 listed by Herbig &Bell (1988).

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3.2. Velocity curve and orbital elements of Haro 1-14c

During our survey for spectroscopic pre-main sequence binaries, we discovered that Haro 1-14cis a spectroscopic binary with the exceptionally long period of 590.78 days. It is a single-linedspectroscopic binary, and in none of our spectra have we seen any indication of the secondarycompanion. Our radial velocity observations are listed in Table 2, and the resulting orbital elementsare given in Table 3. The radial velocity observations with our solution superimposed are presentedin Figure 3. The very high eccentricity of 0.617 is evident in the asymmetric velocity curve. Suchhigh eccentricities are rarely seen among PMS binaries, and then only at longer periods (see Mathieu1992 for a discussion).

We have no constraints on the inclination of the orbital plane to the plane of the sky, If weadopt i = 30o, the peak of the probability distribution, then the semimajor axis of the orbit is0.72 AU. Without any information on the secondary we cannot estimate the semimajor axis of thecombined orbit, but it seems reasonable to adopt 2 AU just as an order of magnitude estimate. Theprojected separation between Haro 1-14 and Haro 1-14c is 12.9 arcsec, which at an assumed distanceof 140 pc corresponds to 1800 AU. Even within the uncertainties due to unknown projection effects,it is therefore clear that the Haro 1-14 triple system is an extreme case of a hierarchical system,with a ratio of semimajor axes of the order of one thousand.

4. THE DOUBLE-LINED SPECTROSCOPIC BINARY PARENAGO 2494

4.1. The pre-main sequence nature of P2494

P2494 (= Brun 1069 = HBC 487 = NSV 2456 = BD –06o1258) is located about 50 arcminutessouth-east of the Orion Nebula (Parenago 1954). It is a relatively bright star, with a V-magnitudeof 10.8. As argued below, P2494 is almost certainly a member of the large clustering of pre-mainsequence stars centered on and stretching for more than a degree around the Trapezium at adistance of about 470 pc (van Altena et al. 1988). When placed in an HR diagram, the clustermembers of later types than about A0 are located above the ZAMS. The young stellar populationspans a range in ages, from recently born stars to stars several million years old.

Various spectroscopic classifications of P2494 appear in the literature. Walker (1969) listed itas G0, but this classification is of unknown provenance. Smith et al. (1983) studied the Na D linesof a number of stars in Orion and classified P2494 as F7IV, but recognized the uncertainty of thisestimate. A real MK classification based on a blue photographic slit spectrum has been given byWalker (1983), who finds K0(e)IV, with an uncertainty of about one sub-class, and noting that theCa II H plus K lines are in emission. McNamara et al. (1989) classify P2494 as G8var. Strom etal. (1989,1990) suggest a type of K0V, and note that Hα is filled in by emission. Examining thevarious classifications and their accuracies, we here adopt the spectral type K0e IV/V for P2494.

P2494 shows prominent Lithium in its spectrum (Strom et al. 1989, King 1993). It has

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virtually no near-infrared excess (Rydgren & Vrba 1984), but was detected with co-added IRASfluxes (Weaver & Jones 1992). Finally, we note that P2494 was detected as an X-ray source by theEINSTEIN satellite (Strom et al. 1990, Gagne & Caillault 1994), and was similarly detected bythe ROSAT satellite with a high confidence level and with an X-ray luminosity of log Lx = 31.0[erg/s] (J. Alcala, priv. comm.).

Membership probabilities of the Orion cluster stars have been estimated in various studies.For P2494, McNamara & Huels (1983) estimate a probability of 96%, and McNamara et al. (1989)determine 68%, whereas Tian et al. (1996) find 0%, although these latter authors recognize thatthis conflicts with the many pre-main sequence characteristics of the star.

Altogether, evaluating the various observations, we conclude that it is well established thatP2494 is a low mass pre-main sequence star, which, based on the characteristics discussed above,we conclude is a weak-line T Tauri star.

4.2. Velocity curve and orbital elements of P2494

We have found that P2494 is a double lined spectroscopic binary with a period of about 19.5days. Our radial velocity observations are listed in Table 4, and the orbital solution is given inTable 5. Figure 4 shows the radial velocity curve with our solution superimposed; component Ais marked with black squares, and component B with white squares. The mass ratio is 0.7, andthe system is modestly eccentric, with e = 0.26. The two dips in the correlation function arewell defined, and have rather different depths, as illustrated in Figure 5. The vsini determined forcomponent A is 22.0 ±2.2 km s−1, and 11.4 ±2.0 km s−1 for component B.

While studying the literature on P2494 we found the following remark by King (1993): “P2494’sspectrum also shows a consistent, clear set of double lines”. It follows that he independentlydiscovered the spectroscopic binary nature of P2494.

4.3. Photometric Variability of P2494

We have obtained photometric observations of P2494 with the 70cm Swiss Telescope at LaSilla on 35 nights during the period Dec 1, 1990 to Feb 20, 1991 using the Geneva photometricsystem. The Geneva V magnitude is very accurately transformed to the Johnson V system, and wefind that the star is variable between V = 10.65 and V = 10.75. A period analysis kindly performedby Gilbert Burki reveals a clear period of 5.77 days, as illustrated in Figure 6. We interpret thisvariability as the result of large star spots on the primary component, which presumably dominatesthe lightcurve; such spots are ubiquitous among the weak-lined T Tauri stars (e.g. Bouvier &Bertout 1989). It follows that the rotational period of the primary is less than a third of the orbital

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period of the system, showing that orbital synchronization has not taken place, consistent with thelarge separation between the components.

5. FURTHER VELOCITY VARIABLES

In the course of our radial velocity survey of pre-main sequence stars, we discovered a smallnumber of velocity variable stars. Pre-main sequence stars are generally faint for the CORAVELinstrument. Furthermore, classical T Tauri stars are often fast rotators, sometimes complicatinga precise determination of a centroid velocity. Also, the presence of large star spots can influencethe shape of the cross correlation profile. Finally, the presence of a companion with small veloc-ity separation can for fast rotators produce distortions to the combined cross correlation profile.Altogether, several unknown factors are involved in the final radial velocity determination.

When examining our large data set of radial velocities for more than 100 pre-main sequencestars, 5 stars stood out as showing tantalizing velocity variations, and they are briefly discussedin the following. In all cases, the amplitudes are so low that errors on the individual observationsbecome important. Combined with the sometimes low number of observations, we are thus notable to determine if they are truly new spectroscopic PMS binaries, although we suspect that atleast some of them will prove to be binaries when examined with the latest generation of radial ve-locity techniques. Alternatively, large starspots could induce velocity-shifts of the small magnitudeobserved for these stars. Here we merely present an overview of our results for these 5 stars, withfurther details about the observations given in Table 6.

V1044 Ori (HBC 113, P1404) is a classical T Tauri star of spectral type G5 IV/V. Weobserved it 29 times between Dec 1988 and Dec 1990 and found a velocity amplitude of 5 km s−1

on timescales of days. We suspect that V1044 Ori is particularly rich in starspots, which causedistortions to the cross correlation profile, rather than being a spectroscopic PMS binary.

SY Cha (HBC 565, Sz 3, HM 2) is a T Tauri star with a spectral type of M0. It has showncyclic variations in brightness of one magnitude in V with a period of 5.97 days (Batalha et al.1998). We observed it 10 times between January 1989 and January 1996. Our observed velocityamplitude of 8.4 km s−1 is large, and the velocities are rather well defined as the vsini is thesmallest of the 5 velocity variable stars discussed here. This could be a real spectroscopic PMSbinary, and our data suggests a possible period around 23 days. But more observations are neededfor confirmation.

CV Cha (HBC 247, LHα 332-21, HM 30) is a classical T Tauri star with a spectral type ofG8V. It has a rotational period of 4.4 days (Bouvier et al. 1986). We observed it 19 times betweenDecember 1988 and January 1996. The scatter in the observations is large, and we could not finda well defined solution to the data.

Sz 41 (HBC 588) is a weak-line T Tauri star with a spectral type of K0. It has a fainter

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visual companion at a separation of 1.9 arcsec, which was included in the CORAVEL entrancewindow (Reipurth & Zinnecker 1993). We observed it 16 times between January 1989 and January1996. This is perhaps the best candidate for a spectroscopic PMS binary among these 5 velocityvariable stars. A formal solution to our data suggests a possible period of about 125 days. Butmore observations are needed for confirmation.

SZ Cha (HBC 566) is a weak-line T Tauri star with a spectral type of K0. It has a faintcompanion with a separation of 5.3 arcsec (Ghez et al. 1997). We observed it 10 times betweenDecember 1988 and March 1995. A fairly good fit with a 5 day period can be made to the (limited)observations, and this appears to be another good candidate for a spectroscopic PMS binary.

6. CONCLUSIONS

We have used the CORAVEL at the Danish 1.5m telescope at La Silla to survey about 100mostly southern PMS stars in search of spectroscopic PMS binaries.

1. We have found two new spectroscopic PMS binaries. Haro 1-14c is located in the Ophiuchusclouds, is single-lined, very eccentric, and has an extremely long period of 591 days. Parenago 2494is in the Orion clouds, is double-lined and has a period of 19.5 days.

2. The relatively low number of spectroscopic PMS binaries found as compared to whatwould be expected for late-type main sequence stars is likely due to the sometimes wide and oftencomplex line profiles of T Tauri stars, which limits detection to spectroscopic binaries with ratherhigh velocity amplitudes. Weak-line T Tauri stars have much less complex line profiles than classicalT Tauri stars, and it is therefore not surprising that the two spectroscopic binaries we have foundare both weak line T Tauri stars.

3. We additionally identify 5 stars which are clearly velocity variables, but for which theamplitudes are rather low, so measurement errors and sometimes limited observations make itdifficult to determine unequivocally if they are bona fide spectrocopic PMS binaries. Alternatively,some of these stars could have large star spots, which represent another complication in the searchfor spectroscopic binaries among PMS stars. At least the stars Sz 41 and SZ Cha appear tobe good candidates for spectroscopic PMS binaries, but definite confirmation will require furtherobservations.

4. We note a spectroscopic binary, Parenago 2445, that is located towards the Orion Nebula,with photometric and spectroscopic properties and a radial velocity that suggest it could be locatedat the distance of this star forming region. However, it has none of the usual PMS characteristics,and it therefore appears to be an interloper in the Orion Nebula region (see Appendix).

We are grateful to Stephane Udry for accessing the CORAVEL data base in Geneva, to HugoSchwarz for taking spectra of Haro 1-14 and 1-14c, to Per Kjaergaard Rasmussen for obtaining a

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spectrum of P2494, to Johannes Andersen for taking several CORAVEL measurements of Haro 1-14c at a critical phase, and to Birgitta Nordstrom for obtaining additional CORAVEL measurementsof V1044 Ori. We thank Gilbert Burki for deriving the photometric period of P2494 with his Fouriercode for period analysis. Juan Alcala kindly provided information on ROSAT observations of thetwo Parenago stars. Finally, we thank the referee, R.D. Mathieu, for helpful suggestions.

APPENDIX: THE PUZZLING CASE OF P2445

In the course of a radial velocity study of F and G type stars in the Orion region, one of us(J.-C.M.) found Parenago 2445 to be a spectroscopic binary. It is a relatively bright star withmV = 11.13. Walker (1969) classified it as of spectral type G7. Smith et al. (1983) analysed theNa D lines, and derived a spectral type of F9 IV, with considerable uncertainty. P2445 is locatedat α2000 05h 36m 50.8s, δ2000 –04o 59′ 33′′, merely 30 arcminutes north-east of the center of theOrion Nebula, so close to the nebula that it is surrounded by extended diffuse emission filaments.McNamara & Huels (1983) assigned it an 82% Orion cluster membership probability based ona proper motion analysis. Also, P2445 and P2494 have the same system velocity to within themeasurement uncertainty. In view of this we suspected that P2445 could be another spectroscopicpre-main sequence binary. However, this appears not to be the case. Discussions of spectra ofP2445 do not mention any emission lines (e.g. Duncan 1993), it does not have any infrared excess(Rydgren & Vrba 1984), there is no Lithium absorption detectable on echelle spectra (Mathieu &Marschall, priv. comm.), it is not a known X-ray source in the ROSAT sky survey (Alcala, priv.comm.), it is not listed as a variable or suspected variable star in the General Catalogue of VariableStars, and it is not considered a member of the Orion cluster by the most recent proper motionstudy (e.g. Tian et al. 1996). Thus, whereas P2494 shows numerous characteristics of being apre-main sequence star, P2445 shows none. P2445 has about the right V-magnitude for its spectraltype to be located at the distance of the Orion Nebula, and its system velocity (24 km s−1) isclose to the mean velocity of the cluster members. So although it seems likely that P2445 is indeedphysically located in the neighborhood of M42, we must conclude that it probably is an interloperin the region of the Orion Nebula. For the record we provide the orbital solution in Table 7.

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This preprint was prepared with the AAS LATEX macros v5.0.

Table 1. Two new spectroscopic PMS binaries

Object α2000 δ2000 V

Haro 1-14c 16 31 04.4 −24 04 33 13.7 - 14.5Parenago 2494 05 37 09.5 −06 06 16 10.74 - 10.85

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Table 2. Radial velocity observations of Haro 1-14c

phase JDa Obs.vel.b m.e.b O-Cb Weight

0.006 47739.594 –15.34 0.50 0.17 80.025 48341.875 –10.55 0.52 0.11 80.027 48342.871 –10.10 0.48 0.19 80.029 48343.898 –9.71 0.52 0.21 80.031 48344.879 –9.43 0.48 0.16 80.032 48345.895 –9.07 0.49 0.18 80.036 48347.863 –9.08 0.49 –0.43 80.039 48349.727 –8.73 0.49 –0.61 80.075 48370.883 –4.44 0.49 0.22 80.076 48371.863 –4.47 0.52 0.11 80.085 47786.535 –4.07 0.50 0.12 80.087 47787.543 –4.44 0.52 –0.31 80.088 48378.812 –4.10 0.46 0.01 90.089 47788.523 –3.25 0.55 0.83 70.092 47790.523 –3.99 0.57 –0.01 70.096 48383.820 –3.85 0.49 0.02 80.105 48388.805 –3.69 0.56 0.00 70.120 48397.914 –2.94 0.52 0.56 80.122 48398.734 –3.71 0.48 –0.23 80.124 49581.480 –3.55 0.47 –0.08 90.174 48429.656 –3.96 0.48 –0.52 80.177 48431.590 –4.20 0.52 –0.74 80.206 48448.645 –3.50 0.48 0.13 80.208 48449.625 –4.62 0.47 –0.98 90.231 48463.578 –3.57 0.47 0.26 90.244 49061.895 –3.77 0.47 0.17 90.278 49081.867 –4.49 0.45 –0.24 90.323 47926.836 –4.88 0.51 –0.17 80.340 49118.762 –4.02 0.46 0.87 90.343 47938.836 –5.27 0.49 –0.35 80.372 48546.512 –4.63 0.54 0.60 70.376 47957.910 –5.01 0.60 0.26 7

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Table 2—Continued

phase JDa Obs.vel.b m.e.b O-Cb Weight

0.425 47986.867 –5.80 0.59 0.03 70.433 47991.875 –4.90 0.52 1.03 80.477 48017.824 –6.26 0.56 0.20 70.481 49792.836 –7.30 0.49 –0.79 80.497 48029.805 –6.30 0.60 0.41 70.531 48049.676 –7.16 0.52 –0.01 80.540 48054.809 –6.99 0.51 0.28 80.573 48074.633 –8.65 0.48 –0.91 80.574 49256.527 –7.82 0.49 –0.07 80.597 48088.598 –8.07 0.47 0.02 90.608 48685.859 –8.68 0.48 –0.42 80.625 48105.531 –8.85 0.49 –0.31 80.630 48698.898 –8.23 0.49 0.38 80.671 48132.523 –9.14 0.47 0.18 90.684 48730.816 –9.57 0.48 –0.01 80.696 49919.578 –9.77 0.49 0.03 80.717 48159.531 –10.16 0.48 0.07 80.918 47687.781 –17.46 0.51 0.19 80.929 48875.523 –18.04 0.48 0.29 80.932 48877.535 –19.16 0.48 –0.60 80.936 48879.566 –18.96 0.46 –0.18 90.980 48314.859 –18.94 0.53 1.06 80.987 48318.852 –19.97 0.45 –0.60 90.998 48325.828 –17.75 0.49 –0.41 8

aJD = Julian date – 2400000

bMeasurements are in km s−1

– 14 –

Table 3. Spectroscopic orbital elements of Haro 1-14c

Orbital Element Value Error(±) Unit

System velocity V0 -8.71 0.07 km s−1

Orbital period P 590.78 1.00 daysSemi-amplitude K 8.47 0.13 km s−1

Time of periastron passage t0 2445372.9 5.0 HJDPeriastron angle ω 232.9 1.3 degrees

asini 54.2 1.3 GmEccentricity e 0.617 0.008Mass function f(M) 0.018 0.001 M�

σo−c 0.46 km s−1

No. of observations N 56

– 15 –

Table 4. Radial velocity observations of P2494

phase JDa Obs.vel.b m.e.b O-Cb Obs.vel.b m.e.b O-Cb Weight

0.001 47558.391 41.57 0.76 –0.09 50.012 45727.352 45.44 0.76 0.13 –6.66 1.14 –0.55 5/40.025 48162.781 48.23 0.85 –1.23 50.027 48162.809 –14.47 0.85 –1.85 50.033 47208.348 51.80 0.67 0.12 60.046 48377.484 54.06 0.85 –0.87 50.047 48377.496 –21.53 1.33 –1.50 30.049 48221.676 54.63 0.67 –0.78 60.050 48221.703 –20.40 0.95 0.56 40.073 48319.555 58.07 0.67 –1.60 60.074 48319.582 –26.98 1.63 –0.11 20.078 48163.809 61.50 0.76 1.16 50.080 48163.840 –29.58 1.24 –1.76 30.098 48222.645 62.21 0.76 0.22 50.099 48222.660 –29.01 0.85 0.97 50.123 48320.523 61.41 1.04 –1.01 40.130 48164.816 61.72 0.67 –0.54 60.130 48164.824 –30.88 1.63 –0.58 20.131 48203.793 61.97 0.76 –0.27 50.132 48203.820 –32.64 1.53 –2.42 30.173 48321.512 58.55 0.95 –0.77 40.180 48204.758 56.61 0.58 –2.00 70.181 48204.777 –24.76 1.14 0.19 40.181 48165.812 58.92 0.76 0.40 50.182 48165.824 –24.50 1.04 0.37 40.189 46373.688 59.82 0.95 2.22 40.190 46373.695 –23.82 1.73 –0.23 20.203 47893.500 56.06 0.85 0.11 50.203 47893.508 –19.52 1.04 1.71 40.214 46471.578 56.67 1.24 2.16 30.215 46471.590 –17.99 2.02 1.14 20.225 48322.516 53.59 0.95 0.52 4

– 16 –

Table 4—Continued

phase JDa Obs.vel.b m.e.b O-Cb Obs.vel.b m.e.b O-Cb Weight

0.228 48283.605 52.54 0.67 –0.15 60.228 48283.617 –15.22 1.04 1.31 40.233 48166.820 52.70 0.95 0.74 40.233 48166.828 –14.31 1.04 1.21 40.274 47232.516 45.99 0.76 0.04 –10.20 1.14 –3.17 5/40.276 48323.516 46.63 0.95 1.01 40.284 48167.824 43.81 0.76 –0.58 –6.74 1.14 –1.94 5/40.286 48167.852 –5.78 1.04 –1.28 40.288 47505.523 43.72 0.76 –0.16 50.293 47583.559 44.40 0.95 1.36 40.326 47233.527 39.24 0.76 1.09 0.14 1.14 –3.98 5/40.327 48324.508 37.65 0.85 –0.31 4.20 1.43 –0.18 5/30.335 48168.805 37.13 0.67 0.30 6.97 0.95 0.97 6/40.339 47506.531 38.28 0.85 2.16 11.91 1.33 4.90 5/30.362 47565.410 33.47 1.04 0.65 14.53 1.63 2.81 4/20.378 47234.535 31.33 0.76 0.81 15.36 1.24 0.36 5/30.378 48325.508 31.76 0.85 1.36 15.59 1.43 0.42 5/30.386 48169.797 30.98 0.76 1.61 15.87 1.04 –0.78 5/40.392 47507.555 27.65 0.95 –0.81 22.59 1.53 4.64 4/30.430 48326.508 20.38 0.85 –2.81 29.65 1.33 4.19 5/30.446 47586.527 20.04 0.95 –1.00 30.67 1.43 2.13 4/30.493 47509.523 13.29 0.85 –1.63 34.30 1.33 –2.98 5/30.541 48172.820 10.70 0.76 1.51 47.46 2.02 2.00 5/20.544 47510.520 9.00 0.67 0.20 60.548 47588.527 9.28 0.76 0.96 46.15 1.14 –0.54 5/40.601 47589.555 2.84 0.95 0.12 55.28 1.53 0.59 4/30.639 48252.660 -1.49 0.76 –0.70 50.640 48252.684 56.45 1.14 –3.41 40.652 47590.543 -2.97 0.76 –1.11 61.20 1.14 –0.03 5/40.690 48253.648 63.85 1.24 –1.27 30.691 48253.664 -4.42 0.58 0.21 70.701 47591.508 -5.25 0.95 0.01 66.41 1.53 0.32 4/3

– 17 –

Table 4—Continued

phase JDa Obs.vel.b m.e.b O-Cb Obs.vel.b m.e.b O-Cb Weight

0.744 48254.699 -6.29 0.58 0.68 70.746 48254.734 66.99 1.14 –1.59 40.780 47573.559 -9.26 0.76 –2.12 70.03 1.53 1.25 5/30.797 47554.414 -5.92 0.76 0.76 50.833 47457.695 -5.70 1.04 –1.38 40.866 48315.520 -0.34 0.95 –0.39 40.866 48315.531 60.32 1.33 1.95 30.882 47575.543 4.15 0.76 1.06 55.77 1.24 1.60 5/30.895 47887.508 7.41 0.85 1.29 50.909 46465.633 8.30 0.85 –1.33 42.10 1.33 –2.73 5/30.915 46309.898 11.17 0.76 –0.14 42.01 1.14 –0.42 5/40.984 47577.531 36.64 0.85 1.31 11.09 1.33 2.95 5/3

aJD = Julian date – 2400000

bMeasurements are in km s−1

– 18 –

Table 5. Spectroscopic orbital elements of P2494

Orbital Element Value Error(±) Unit

System velocity V0 +24.13 0.16 km s−1

Orbital period P 19.48136 0.00039 daysSemi-amplitude KA 34.85 0.28 km s−1

KB 49.75 0.38 km s−1

Time of periastron passage t0 2445006.305 0.076 HJDPeriastron angle ωA 292.9 1.4 degrees

aAsini 9.024 0.085 GmaBsini 12.882 0.118 Gm

Eccentricity e 0.257 0.005MAsin3i 0.650 0.014 M�MBsin3i 0.455 0.008 M�

Mass function f(MA) 0.077 0.002 M�f(MB) 0.225 0.006 M�σo−c 1.54 km s−1

No. of observations NA 56NB 45

Table 6. Five Velocity Variable PMS Stars

Object Vamax Va

min ∆Va Nobs Vasini Sp.T. mV

V1044 Ori +28.5 +23.6 4.9 29 26.0 G5 11.5SY Cha +17.6 +9.2 8.4 10 11.1 M0: 13.0CV Cha +16.6 +12.5 4.1 19 26.3 G8 11.0Sz 41 +15.5 +12.1 3.4 16 31.0 K0 11.6SZ Cha +17.8 +10.1 7.7 10 33.0 K0 12.0

aMeasurements are in km s−1

– 19 –

Table 7. Spectroscopic orbital elements of P2445

Orbital Element Value Error(±) Unit

System velocity V0 +24.18 0.18 km s−1

Orbital period P 118.34 0.10 daysSemi-amplitude KA 20.13 0.36 km s−1

KB 21.63 0.39 km s−1

Time of periastron passage t0 2445015.2 1.2 HJDPeriastron angle ωA 338.0 3.1 degrees

aAsini 31.59 0.73 GmaBsini 33.95 0.78 Gm

Eccentricity e 0.264 0.015Mass function f(MA) 0.090 0.006 M�

f(MB) 0.112 0.008 M�σo−c 1.22 km s−1

No. of observations NA 23NB 24

– 20 –

Fig. 1.— The classical T Tauri star Haro 1-14 with its much brighter visual companion, the weakline T Tauri star Haro 1-14c. Both are located in the Ophiuchus clouds. The image is from a redSchmidt plate in the Digitized Sky Survey

Hβ

1003

671

339

Rel

ativ

e in

tens

ity

Hγ Nα

Hα

7000600050004110Wavelength [A]˚

933

488

43

Rel

ativ

e in

tens

ity

Nα

1378

Fig. 2.— Low dispersion spectra of Haro 1-14 (top) and Haro 1-14c (bottom)

– 21 –

Fig. 3.— Radial velocity observations and the computed orbit for Haro 1-14c

Fig. 4.— Radial velocity observations and the computed orbits for P2494. Component A is markedwith black squares, and component B with white squares

– 22 –

Fig. 5.— Typical cross correlation profiles for the double lined spectroscopic binary Parenago 2494

1.510.50Phase

10.60

10.65

10.70

10.75

10.80

Mag

nitu

de

Fig. 6.— Photometric observations of Parenago 2494 in Johnson-V folded with a period of 5.77days