arXiv:astro-ph/0111255v1 14 Nov 2001 fLno cel pcrgah(CE)ada I an and (UCLES) Spectrograph Echelle College London University the of 2001). using (AAT), al. Telescope et Australian Butler 2001; al. et (Tinney ter 6 rmti rgam eosrt htAP acheives s m AAPS 3 of that precisions velocity demonstrate results systematic Initial long-term, M programme V=7.5. and this of provides limit F,G,K it from magnitude inactive 2000), tele- a to for m 10 down coverage al. dwarfs I et search Keck Vogt planet 2001; and all-sky al. m 3 using et Lick (Fischer programmes the scopes with on Together perform techniques similar to precision. high- the aims possible at measurement which est and program detection planet detection extra-solar planet term 7 umte to Submitted oe ro o20 etme,i a sdwt a with used was it September, 2001 to 2048 Prior MIT/LL mode. 8 rpittpstuigL using typeset Preprint opincl.ULSi prtdi t 1lnsmm lines 31 its in operated is UCLES cell. sorption enue iha E 2048 EEV an with used been 1 u agtsml nlds18FKsaswith FGK 178 includes sample target Our ta.(02)w eur agtsast aeR have to stars target require we (2002)) al. et R from V with V and 2 98 inye l 02.IsHpacspar- Hipparcos Its 2002). 39.0 al. M of et allax Tinney 1978; 3 4 nBte ta.(96 n ulre l (2001). al. et Butler and (1996) described that observ- al. follows et The procedure Butler processing in Gyr). 3 data than and greater ing ages to (corresponding 5 opeial ncie(R inactive mospherically srpyisRsac nttt,LvrolJh orsUn Moores John Liverpool Institute, Research Astrophysics uhrodApeo aoaoy hlo,Ddo,Oo OX1 Oxon Didcot, Chilton, Laboratory, Appleton Rutherford aut fSine,Uiest fSuhr uesad To Queensland, Southern of University Sciences, of Faculty ae nosrain banda h nl–utainTel Anglo–Australian the at obtained observations on Based nl-utainOsraoy OBx26 pig 70 Au 1710. Epping. 296, Box PO Observatory, Anglo-Australian angeIsiuino ahntnDprmn fTerrest of Washington,Department of Institution Carnegie eateto srnm,Uiest fClfri,Berkel California, of University Astronomy, of Department eateto hsc n srnm,SnFacsoSaeUn State Francisco San Astronomy, and Physics of Department V ASi en are u nte39 Anglo- m 3.92 the on out carried being is AAPS h nl-utainPae erh(AS salong- a is (AAPS) Search Planet Anglo-Australian The D12(R6 I 2,G .A H 00 sachro- a is 1020) LHS 4.2A, GJ 522, HIP 6, (HR 142 HD =3.66 2. 1. < < HK ′ .,adafrhr2 n ea nihdstars enriched metal and M 23 further a and 7.5, ecnrc a ins D209le ntercnl noee clas uncovered recently two the under just in ha of lies 142 period 23079 HD HD a orbiting has giants. planet 23079 gas HD The “eccentric” orbiting 23079. that HD while and , 142 one HD stars the around fti ls rvdsnwiptsfrteetnino xsigplane existing orbits. of headings: Jupiter-like extension Subject in the planets for recen Jupiter-like impetus The for new a.u. search provides 0.1 outside class orbits this near-circular of with planets giant gas 15 hr g/ciiyifraini available is information age/activity Where 11.5. hrceitc fh 4 d23079 hd & 142 hd of characteristics h nl-utainpae search planet anglo-australian the ± erpr h eeto ftonwetaslrpaesfo h A the from planets extra-solar new two of detection the report We .3(S 97 n M and 1997) (ESA 0.03 nie seeg,Hnye l 19) Tinney (1996); al. et Henry e.g., (see indices h srpyia Journal Astrophysical The W XR-OA LNT RMTEAGOASRLA LNTS PLANET ANGLO-AUSTRALIAN THE FROM PLANETS EXTRA-SOLAR TWO ± × . a mle bouemgiue of magnitudes absolute implies mas 0.6 0615 4096 ..Tinney C.G. A T E tl mltajv 14/09/00 v. emulateapj style X µ ie C,adsnete has then since and CCD, pixel m HK ′ lntr ytm tr:idvda H12 HD23079) (HD142, individual stars: – systems planetary = 2 .Pu Butler Paul R. , × − 0613.5 4096 4 . . bol 2 1Vsa (Houck G1IV 92) Penny =5.55 µ ± umte to Submitted ie CCD. pixel m 7 hi McCarthy Chris , .5(Alonso, 0.05 HK ′ − 3 < δ efryW Marcy W. Geoffrey , 1 < rbet- or ilMgeim 21BodBac dN,Wsigo,D 2001 DC Washington, NW, Rd Branch Broad 5241 Magnetism, rial y A 94720 CA, ey, wob,45.Australia. 4350. owoomba, 2 − vriy wleQasHue gro hr,Breha CH Birkenhead Wharf, Egerton House, Quays Twelve iversity, − soe iigSrn,Australia. Spring, Siding escope, ABSTRACT Q,U.K. 0QX, 1 20 ab- h srpyia Journal Astrophysical The 4 − stralia. vriy a rnic,C 94132. CA Francisco, San iversity, . 5 1 ◦ 1 [email protected] 3 l .Teclm aeld“netit”i h velocity the is “Uncertainty” labelled column The 1. ble M=1.10 iso ta9%cndnelvlof level 1997). confidence Hipparcos the 95% (ESA of a life at the over mission stable photometrically be to l 19,19) h aso D12i siae obe to estimated is 142 HD of the 1997), et 1.15 Fuhrmann (1998, of inter- tracks on al. evolutionary Based the between uncertainties. polation within to spectroscopy the M asle nterne1012 M 1.0-1.25 its range F/G-dwarf, the this in of lies M range 1.0 mass and and likely 0.0 most 1.10 the [Fe/H]=+0.25, For M=1.25, At esti- indicate mass would precise. so less star, − be this for will available mation is information licity ihaR a is with star this The that 23079. confirms HD inactive. and emission chromospherically significant quiet of the absence with together 142, HD ie nemdaebtenF n 0.IsHipparcos Its F8/G0V as G0). it and 28.9 classify F8 is (1975) between parallax intermediate Cowley & (i.e. Houck 1996). tysget [Fe/H]= suggests etry h oplto fEgn(98) pcrsoyderives Spectroscopy (1998)). Eggen [Fe/H]=+0 of compilation the Fvt ta.19)adStr¨omgren spectroscopy and via 1997) examined been al. pa- et have fundamental (Favata 142 The HD of . rameters 1995) Mart´ınez-Roger & Arribas rdD Carter D. Brad , 0 bol wnysvnosrain fH 4 r itdi Ta- in listed are 142 HD of observations Twenty-seven D209(I 79,LT13)i niatv dwarf inactive an is 1739) LTT 17096, (HIP 23079 HD . 3. 5 h oeso urane l 19,1997) (1998, al. et Fuhrmann of models the 25, ± =4.25 0.1M ailvlct bevtosadorbital and observations velocity radial ± 4,5 HK ′ 0.15M ± uhRA Jones R.A. Hugh , ⊙ . 04 .5(S 97 ag19) ometal- No 1992). Lang 1997; (ESA 0.05 f“ of s iue1sosteCa the shows 1 Figure . = icvr fsvrlmr members more several of discovery t . ± erhst ogrpros nthe in periods, longer to searches t er.H 4 al notecasof class the into falls 142 HD . − 0 ± ⊙ 4 nobtlpro fjs under just of period orbital an s . . 5adT and 15 ǫ ohH 4 n D209wr seen were 23079 HD and 142 HD Both . . a,gvn tM it giving mas, 0.6 6(inye l 02 er tal. et Henry 2002; al. et (Tinney 96 goAsrla lntSearch Planet nglo-Australian e-ie lnt extra-solar – planets Ret-like” 8 − 0 solutions . 4 hc si gemn with agreement in is which 04, e ff 62 ,wietephotom- the while K, =6025 6 lnJ. Alan , ⊙ n eteeoeadopt therefore we and , EARCH ubvy < II V .1 magnitudes 0.018 iergo for region line H ⊙ =4.42 htmty(see photometry 11D UK 1LD, 41 (respectively). 1 5-1305 ± .5and 0.05 2 Planets from the Anglo-Australian Planet Search uncertainty produced by our least-squares fitting. This Together with the extra-solar planetary companions to fit simultaneously determines the Doppler shift and the ǫ Ret (Butler et al. 2001), HD4208 (Vogt et al. 2002), spectrograph point-spread function (PSF) for each obser- 47UMab&c (Fischer et al. 2002), and possibly the com- vation made though the iodine cell, given an iodine absorp- panions to HD114783 and HD10697 (Vogt et al. 2002, tion spectrum and an “iodine free” template spectrum of 2000), HD23079 forms a new class of extra-solar planets, the object (Butler et al. 1996). The uncertainty is de- which we name after the prototype object ǫ Ret. The re- rived from the ensemble of velocities from each of four gion of the Log(e) versus Log(amaj) diagram these “ǫ Ret- hundred useful spectral regions (each 2 A˚ long) in every like” planets occupy is highlighted in Fig. 4. It is worth exposure. This uncertainty includes the effects of photon- remembering that prior to about 12 months ago the high- counting uncertainties, residual errors in the spectrograph lighted region of this plot was empty – though many extra- PSF model, and variation in the underlying spectrum be- solar planets had been discovered, none shared orbital tween the template and “iodine” epochs. All velocities are properties with the planets of our own Solar System. The measured relative to the zero-point defined by the template “ǫ Ret-like” planets, therefore, join with the “51 Peg-like” observation. Only observations where the uncertainty is and eccentric giant planets in filling out the bestiary of less than twice the median uncertainty are listed. These extra-solar planets. Prior to their detection, it was unclear data are shown in Figure 2. The figure shows the best-fit whether giant planets in circular, or near-circular, orbits Keplerian model for the data, with the resultant orbital outside 0.1 a.u. would be found at all outside the Solar parameters listed in Table 2. System. Their discovery points the way to the detection The residuals about the fit are slightly higher than the of Solar System analogs (in the form of Jupiter-like-planets 3-4ms−1 average level of “jitter” expected in a G1 star in Jupiter-like-orbits) once data sequences at better than with HD 142’s level of activity (Saar et al. 1998), but is 2-3ms−1 span the necessary 10-12 year periods. within the typical range seen in even inactive stars9. The thirteen observations of HD 23079 are listed in Ta- 5. conclusions ble 3, and they are shown in Figure 3 along with a Kep- lerian fit to the data with the orbital parameters listed in We present results for the detection and characterisation Table 2. The rms scatter about this fit of only 3.08ms−1 for two new extra-solar planets with orbital periods of one demonstrates the extra-ordinary control over long term year or greater around the stars HD142 and HD23079. systematics which the iodine cell technique can deliver The planet around HD 23079 is particularly interesting – for stars with suitable intrinsic velocity stability. It also it represents the detection of a new member of the class demonstrates the suitability of the UCLES spectograph of “ǫ Ret-like” giant planets in near-circular orbits out- at the AAT for radial velocities at the highest precisions – side 0.1 a.u.. The continued detection by high precision even for a V=7.1 star near our V=7.5 current survey limit. Doppler searches of these gas giants, in Solar System-like orbits, gives added impetus that the continuation of these 4. discussion searches to the 10-12 year periods where analogs of the gas The resultant minimum companion mass for HD 142 giants in our own Solar System may become detectable around other stars. is M sin i = 1.03±0.19 MJUP, with an orbital semi-major axis a = 1.0±0.1 au at an eccentricity of e = 0.37±0.1 – a roughly Jupiter-mass in an Earth-like, but The Anglo-Australian Planet Search team would like eccentric, orbit. An interesting feature of HD 142 is that to gratefully acknowledge the support of Dr Brian its metallicity is only marginally enriched over solar. This Boyle, Director of the AAO, and the superb techni- planet, at least, has not formed in a metal-enriched sys- cal support which has been received throughout the tem, as has been suggested for many of the extra-solar programme from AAT staff - in particular E.Penny, planets (e.g. see Gonzalez et al. (2001) and references R.Patterson, D.Stafford, F.Freeman, S.Lee, J.Pogson and therein). G.Schafer. We further acknowledge support by; the The minimum companion mass and orbital pa- partners of the Anglo-Australian Telescope Agreement rameters derived for HD23079 (Msin i=2.5±1.1 MJUP, (CGT,HRAJ,AJP); NASA grant NAG5-8299 & NSF grant a=1.5±0.2 au, e=0.04±0.18) indicate the presence of a AST95-20443 (GWM); NSF grant AST-9988087 (RPB); planet with significantly larger mass than Jupiter, in and Sun Microsystems. NSO/Kitt Peak FTS data used a -like orbit with eccentricity consistent with zero. here were produced by NSF/NOAO.

REFERENCES

Alonso, A., Arribas, S. & Mart´ınez-Roger, C. 1995, A&A, 297, 197 Fischer D., Marcy G., Butler P., Laughlin G. & Vogt S., 2002, ApJ, Butler, R.P., Marcy, G.W., Williams, E., McCarthy, C. & Dosanjh, in press. P. 1996, PASP, 108, 500 Fuhrmann, K., Pfeiffer, M.J. & Bernkopf, J. 1997 A&A, 326, 1081 Butler, R.P., Tinney, C.G., Marcy, G.W., Jones, H.R.A., Penny, A.J., Fuhrmann, K., Pfeiffer, M.J. & Bernkopf, J. 1998 A&A, 336, 942 Apps, K. 2001, ApJ, 555, 410 (Paper II) Gonzalez G., Laws C., Tyagi S., Reddy B. E., 2001, AJ, 121, 432 ESA, 1997, The Hipparcos and Tycho Catalogues, ESA SP-1200 Henry, T.J., Soderblom, D.R., Donahue, R.A. & Baliunas, S.L. 1996, Eggen, O.J. 1998, AJ, 115, 2397 AJ, 111, 439. Favata, F., Micela, G. & Sciortino, S. 1997, A&A, 323, 809 Houck, N. and Cowley, A.P. 1975, Michigan Catalogue of Two Fischer, D. A., Marcy, G. W., Butler, R. P., Vogt, S. S., Frink, S., & Dimensional Spectral Types for the HD stars, Volume 1, Michigan Apps, K. 2001, ApJ, 551, 1107 Spectral Survey: Ann Arbor

9 “Jitter” here is used to refer to the scatter in the observed velocity about a mean value in systems observed over the long-term to have no Keplerian Doppler shifts, or about a fitted Keplerian in systems known to have a planetary mass companion. It is thought to be due to the combined effects of surface inhomogeneties, stellar activity and . Tinney et al. 3

Houck, N. 1978, Michigan Catalogue of two dimentional spectral Tinney, C.G., Butler, R.P., Marcy, G.W., Jones, H.R.A., Penny, A.J. types for the HD stars, Volume 2, Michigan Spectral Survey: Ann Vogt, S.S., Apps, K. & Henry, G.W. 2001, ApJ, 551, 507 (Paper Arbor I) Kurucz, R.L., Furenlid, I. Brault, J. & Testerman, L. 1984, Solar Flux Tinney, C.G., McCarthy, C., Jones, H.R.A., Butler, R.P., Carter, Atlas from 296 to 1300 nm, National Solar Observatory Atlas No. B.D., Marcy, G.W., & Penny, A.J. 2002, MNRAS, (submitted) 1 Vogt, S.S., Marcy, G.W., Butler, R.P. & Apps, K. 2000, ApJ, 536, Lang, K.R. 1992, Astrophysical Data: Planets and Stars, Springer- 902 Verlag: New York Vogt, S.S., Butler, R.P., Marcy, G.M., Fischer, D.A., Saar, S.H., Butler, R.P. & Marcy, G.W. 1998, ApJ, 403, L153 Pourbaix, D. Apps, K., Laughlin, G. 2002, ApJ, submitted http://xxx.lanl.gov/abs/astro-ph/0110378.

Fig. 1.— Comparison of the Ca II H line core in the Sun (lower line), HD 23079 (middle line) and HD 142 (upper line). Solar spectrum is from Kurucz et al. (1984) and other spectra are from Tinney et al. (2002). 4 Planets from the Anglo-Australian Planet Search

Fig. 2.— AAT Doppler velocities for HD 142 from 1998 January to 2001 October. The solid line is a best fit Keplerian with the parameters −1 shown in Table 2.The rms of the velocities about the fit is 5.89 ms . Assuming 1.15M⊙ for the primary, the minimum (M sin i) mass of the companion is 1.03±0.19 MJUP, and the semimajor axis is 1.0±0.1 au. Tinney et al. 5

Fig. 3.— AAT Doppler velocities for HD 23079 from 1998 January to 2001 October. The solid line is a best fit Keplerian with the parameters −1 shown in Table 2. The rms of the velocities about the fit is 3.08 ms . Assuming a 1.1M⊙ for the primary, the minimum (M sin i) mass of the companion is 2.5±0.3MJUP, and the semimajor axis is 1.5±0.2 au. 6 Planets from the Anglo-Australian Planet Search

1

Mercury

e HD10697 HD114783 0.1 Mars 47 Uma b Jupiter HD23079 HD4208

eps Ret Earth

0.01 47 Uma c Venus Eccentricity, Eccentricity,

0.001 0.01 0.1 1 10 Semi-major axis, a (a.u.)

Fig. 4.— Log(e) versus Log(a) for extra-solar planets reported as of 2001 September, plus the new planets reported in this paper and by (Vogt et al. 2002) (solid circles), together with the inner planets of the Solar System (shaded circles). Planets with measured eccentricities e< 0.01 are shown as upper limits at e = 0.01. The region of the Log(e)-Log(a) occupied by the planets of the Solar System, and its similarity to those of the “ǫ Ret-like” planets is highlighted. Tinney et al. 7

Table 1 Velocities for HD 142

JDa RVa Uncertainty (-2450000) (ms−1) (ms−1) 830.9587 -13.1 7.5 1121.0194 -16.0 7.5 1385.3105 42.6 14.5 1411.2025 13.0 15.8 1473.0850 -15.2 7.9 1683.3314 36.1 8.1 1743.2765 41.0 7.5 1745.2642 24.0 10.4 1767.2699 0.1 9.0 1768.2542 1.3 7.1 1828.0607 -16.4 8.9 1856.0643 -5.9 10.7 1856.9250 -12.5 12.9 1918.9407 -4.1 9.3 2061.2963 32.7 8.0 2092.2683 19.8 7.5 2093.2876 11.4 8.1 2127.2230 -20.0 9.4 2128.1545 -4.0 9.0 2130.2433 -16.0 8.0 2151.2113 -21.9 7.4 2152.0786 -12.0 7.8 2154.1541 -29.5 6.9 2187.1000 -15.2 7.0 2188.0360 -9.4 7.2 2189.0199 -23.9 7.0 2190.0032 -12.0 6.4

aRadial Velocities (RV) are barycen- tric, but have an arbitrary zero-point determined by the of the template, as described in Section 3 8 Planets from the Anglo-Australian Planet Search

Table 2 Orbital Parameters

Parameter HD142 HD23079

Orbital period P (d) 339±6 626±24 Velocity amp. K (m s−1) 29.6±5 56±5 Eccentricity e 0.37±0.1 0.02±0.12 ω (◦) 71±36 262±50 6 6 a1 sin i (km) (0.1280±0.0066)×10 (0.482±0.019)×10 PeriastronTime (JD-2450000) 1752±22 1680±90 M sin i (MJUP) 1.03±0.19 2.5±0.3 a (AU) 1.0±0.1 1.5±0.2 RMS about fit (m s−1) 5.89 3.08

Table 3 Velocities for HD 23079

JDa RVa Uncertainty (-2450000) (ms−1) (ms−1) 831.0689 -42.1 5.3 1121.1268 27.7 12.0 1157.0594 33.6 11.0 1473.2492 -54.6 5.6 1828.1399 51.0 5.8 1920.0142 35.7 6.0 1983.8858 4.4 7.8 2092.3211 -44.2 4.7 2127.2797 -58.5 7.3 2151.2764 -57.9 5.0 2152.2093 -65.5 5.4 2187.1679 -59.2 5.0 2188.1270 -62.1 4.7 2189.1418 -58.3 5.2

aAs for Table 1