Protoplanetary discs of isolated VLMOs discovered in the IPHAS survey Luisa Valdivielso (IAC) ‏ Collaborators: E. Martín, H. Bouy, E. Solano, J.Drew, R. Greimel, B. Riaz 10/09/2009

2 Aims Search young low mass objects on the IPHAS survey Spectral type (SpT) classification with low resolution spectroscopy of the targets Study the chromosferic/accretion activity measuring the H  equivalent width NaI doublet (818.3nm, 819.5nm) equivalent width as surface gravity indicator Distance estimation and comparison with known SFR’s Spitzer photometry, SED’s & disc properties L. Valdivielso

3 Outline L. Valdivielso Introduction Data selection & observations Results Conclusions & perspectives

Introduction Very low mass objects and brown dwarfs L. Valdivielso 4 Many young objects show H  emission due to accretion processes Search in star formation regions such as Chamaeleon,  Oph,  Orionis, Serpens, Taurus, Trapezium… Broadband optical surveys have missed strong Halpha emitters as they appear bluer than they are

5 Introduction: IPHAS Survey Observations with WFC (Wide Field Camera) on Isaac Newton Telescope Filters: r’ (6240 Å), i’ (7743 Å) Sloan, H  (6568 Å) ‏ Magnitude limit r’ ~ º 2 in the North of the Milky Way: search very low mass objects out of the best known star forming regions L. Valdivielso

6 Data: targets selection Cross-match of IPHAS with 2MASS (The Two Micron All Sky Survey) catalogue using Aladin: r’, i’, H , J, H, K photometry of the targets Selection criteria for 2MASS sources: a) 0.7<J-H<1.3 discard strong reddened objects and red giants b) 0.5<H-K<1.1 cool photospheres objects and/or infrared excess IPHAS counterparts: a) 1.1<r’-H  <3.0 b) 16<i’<18.5 c) 1.2<r’-i’<2.2 d) 2.9<i’-J<3.5 red objects L. Valdivielso

7 Data: Observations WHT/ISIS : - Dates: 2006 August targets -t exp : s NOT/ALFOSC : Dates: 2006 October targets t exp : s 3m-Shane Telescope/KAST: - Dates: 2007 July targets t exp : s L. Valdivielso

8 Results 116 IPHAS targets observed:  48 real candidates according new IPHAS photometry  42 objects show strong H  emission (success rate > 80%)  12 objects M5.5-M7  30 between M0-M5.5 L. Valdivielso

H  vs SpT Barrado y Navascués & Martín (2003) criteria to study the accretion level of the targets. All objects with H  emission show accretion L. Valdivielso

NaI doublet measurements NaI doublet equivalent width measurements between 8172Å and 8207Å Comparison with field M dwarfs & Upper Sco members (5Myr) ‏ Later type objects show lower surface gravity L. Valdivielso Upper-Sco

11 Spectro-photometric distances Baraffe Nextgen models log g=4 ; age 5Myr and 2Myr to compute distances SIMBAD search within 30arcmin 16 of them located near molecular clouds, star formation regions and young open clusters: Serpens, North American Nebula, Cep IV, IC1396, Cygnus Some objects not located to any known young association (free- floating ejected from sfr? member of unknown nearby assoc?) L. Valdivielso

12 Spitzer photometry Search Spitzer data to compute SED’s L. Valdivielso Data avaliable for 17 objects Nº objects with µm: 9

13 Spitzer photometry Search Spitzer data to compute SED’s L. Valdivielso Data avaliable for 17 objects Nº objects with µm: 9 Comparison with  –Oph members

14 Preliminary SED analysis L. Valdivielso Robitaille SED online-fitting tool for first estimations of disc properties (Robitaille et al. 2007) ‏ Stellar age ~2.5Myr Stellar mass ~0.14M sun Stellar radius ~1.16R sun Stellar Temperature ~3063K Disk mass ~1.63e-4M sun i(deg) ~40-50 SpT M6

CONCLUSIONS 15 L. Valdivielso  VO tools are very efficient to search for very low mass objects and brown dwarfs using large databases  IPHAS survey to detect new objects using optical wavelengths  We spectroscopically detect very low mass objects in different regions studied until now  Most of the objects with H  emission show evidences of accretion processes and very low surface density indicative of youth  Spitzer data show infrared excesses due to protoplanetary discs

PERSPECTIVES 16 L. Valdivielso  Extend this study using the new release of IPHAS  Originally the goal was complement optical surveys but our study proved to be complementary to mid-IR surveys (SPITZER) as well  Study in more detail the properties of the isolated young VLMOs (kinematics, activity, GAIA, HERSCHEL) ‏  This study can be perform in particular regions to see how many objects have been missed

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