1. GAIA/VLTI - 25 Janvier 2010 Surface Brightness Asymmetries of LPV stars probed by NIR-Interferometric measurements Prospects for the correction on the GAIA parallax S. Sacuto, Vienna Institute of Astronomy A.Jorissen P. Cruzalèbes, E. Pasquato, A. Chiavassa, A. Spang, O. Chesneau & Y. Rabbia

2. GAIA/VLTI - 25 Janvier 2010 VLTI-AMBER observations Observing date (2009) ObjectSpectral Typev (mas)Diam (mas) charm / cadar May & Augustd OphM0.5III19.210 May & Augusta TraK5Ib/K3IIa8.09 May & Augustz AraK3III5.711 May & AugustTW OphCII3.610 NovemberTX PscCII4.310 NovemberR SclCII2.110 NovemberT CetM5IIe4.213 Novembera CarF0II10.46 Novembero 1 CMaK2.5Iab1.69 NovemberL 2 PupM5II16.513 NovemberW OriCII4.710 November119 TauM2Iab1.710 (Proposals P83 and P84: Mid-resolution / l 0 =2.3µm)

3. GAIA/VLTI - 25 Janvier 2010 Objects + Time 119 Tau 6:30 Alp Car 8:32 Alp Tra 3:54 Del Oph 6:28 L2 Pup 7:06 Omi1 CmA 5:39 R Scl 2:02 T Cet 1:13 Tw Oph 10:02 Tx Psc 2:50 W Ori 7:59 Zet Ara 8:27 Base + B p max D0-H0- K0 90.4 m D0-H0- K0 92.8 m A0-DO- H0 95.3 m A0-DO- H0 91.0 m D0-H0- K0 95.0m D0-H0- K0 81.8 m D0-H0- K0 95.3 m D0-H0- K0 94.9 m A0-D0- H0 54.9 m D0-H0- K0 92.7 m D0-H0- K0 93.7 m A0-D0- H0 79.0 m Seeing + Airmass 0.64 1.39 0.74 1.14 0.70 1.44 0.46 1.18 0.99 1.13 1.25 0.51 1.03 0.54 1.01 0.73 1.75 0.82 1.24 0.70 1.19 0.53 1.40 FinitoON OFFON Total number of cal. in the night 154343111263 154 Cal. used + Time 5 5:46 to 7:43 3 2:47 to 8:15 3 2:50 to 4:15 3 5:19 to 7:17 3 6:09 to 7:21 3 1:47 to 2:37 4 1:47 to 3:06 3 0:11 to 01:31 3 8:52 to 10:22 4 1:47 to 3:06 3 6:46 to 7:43 4 5:19 to 8:04 comme nts No.Last calib. (8:47) lead to div. No. Strong div. for some calib. + first lobe No. First lobe No. Err. Visi 2 nd lobe Err. CP 0.3% 1° 0.1% 10° 0.2% 2° 0.01% <1° 0.1% peculiar case 1° first lobe (1%) 1° 0.5% 1° 0.1% peculiar case 1° first lobe (5%) 2° 0.2% 1° 0.1% 1° 0.01% 1° Observation and calibration process

4. GAIA/VLTI - 25 Janvier 2010 Calibrated Squared Visibility

5. GAIA/VLTI - 25 Janvier 2010 Calibrated Cloture Phases

6. GAIA/VLTI - 25 Janvier 2010 Categories 1.Clear evidence of SBA (119 Tau / Alp Tra / Tx Psc) 2.Evidence of SBA (Del Oph / R Scl / W Ori) 3.Poor evidence of SBA (Alp Car / Zet Ara*) 4.First lobe* (Omi1 Cma / TW Oph) 5.Peculiar cases (L 2 Pup / T Cet) * : Use of larger baselines

7. GAIA/VLTI - 25 Janvier 2010 1. Clear evidence of SBA (119 Tau / Alp Tra / Tx Psc)

8. GAIA/VLTI - 25 Janvier 2010 119 Tau TX Psc

9. GAIA/VLTI - 25 Janvier 2010 2. Evidence of SBA (Del Oph / R Scl / W Ori)

10. GAIA/VLTI - 25 Janvier 2010 Del Oph

11. GAIA/VLTI - 25 Janvier 2010 3. Poor evidence of SBA (Alp Car / Zet Ara) A0-H0(p)=79m A0-K0=128m

12. GAIA/VLTI - 25 Janvier 2010 4. First lobe (Omi1 Cma / TW Oph) Circumstellar environment? A0-K0=128m D0-K0(p)=81mA0-H0(p)=55m A0-K0=128m

13. GAIA/VLTI - 25 Janvier 2010 5. Peculiar cases (L2 Pup / T Cet)

14. GAIA/VLTI - 25 Janvier 2010 Uniform disk L2 Pup UD=35mas Binary (Hipparcos) baseline Prim.=40mas Comp.=4mas Sep=27.5mas F c /F p =2.8% ~3 times larger than the 13 mas catalog value !

15. GAIA/VLTI - 25 Janvier 2010 Summary and conclusion  12 Objects (5 categories): ObjectsMorphology 119 Tau Alp Tra Tx Psc Clear evidence of SBA (CP very different from 0±180° / smooth slope 0->180°) Del Oph R Scl W Ori Evidence of SBA (CP¹0±180° / smooth vertical jump 0->180°) Alp Car Zet Ara Poor evidence of SBA (CP~0±180° / clear vertical jump 0->180°) o 1 Cma TW Oph Visibility in the first lobe (possible CE for o 1 Cma!) (Use of larger baseline: A0-K0=128m) L 2 Pup T Cet Peculiar cases (L 2 Pup is 3 times larger than predicted!) (modulation in the visibility profile: possible binarity) The P86 proposal (recently submited) uses the triplet D0-G1-H0 and will constraint this result D0 H0 G1

16. GAIA/VLTI - 25 Janvier 2010 GBOG Nice, 18 Novembre 2009

17. Deviation from the UD model in the 2nd lobe Presence of asymmetries in the second lobe The example of the M0.5III Giant: d Oph (T eff = 3679 K; log g = 1.4) Closure phase: Interferometric measurements of d Oph reveal asymmetric structures on its photosphere. As the signature of these asymmetries appears in the second lobe of visibility, it means that structures of 10 to 30% (1-3 mas) size of the star are detected. Therefore, the size of the spots is about 10 times larger than the one predicted from the simulations of Svensson et al., 2005. This means that SBA could affect the astrometry of LPVs located closer than 300 pc at the level of accuracy of GAIA (~10 µas). We can thus re-evaluate the number of possible threats to the parallax to maybe half of the LPVs observable with GAIA. 2.3µm Visibility: Uniform Disk of 10 mas Measurements 2.3µm 1st lobe 2nd lobe