Comple(ng the Nearby Stellar and Substellar Census with WISE and 2MASS. John Gizis Department of Physics and Astronomy University of Delaware

Transcription

1 Comple(ng the Nearby Stellar and Substellar Census with WISE and 2MASS John Gizis Department of Physics and Astronomy University of Delaware

2 Collaborators Phil Castro Hugh Harris, Fred Vrba A. Burgasser, J. Faherty, M. Shara, M. Liu, K. Allers, N. Deacon, J. Shaw, G. Mace Nick Troup Thanks to WISE and 2MASS teams. Thanks to SpeX archive and its contributors Models from A. Burrows, N. Madhusudhan, T. Tsuji, M. Marley, D. Saumon

3 A WISE- 2MASS Proper Mo(on Survey Overlooked Proper Mo(on Stars Bright brown dwarfs near the Galac(c Plane

4 Wide- field Infrared Survey Explorer Scanned en(re sky in four filters. Preliminary Release covered 58% of sky. WISE is achieving 5σ point source sensi(vi(es be\er than 0.08, 0.11, 1, and 6 mjy in unconfused regions on the eclip(c in bands centered at wavelengths of 3.4, 4.6, 12, and 22μm. Wright et al. (2010)

5 Mo(va(on Lepine- Shara Proper Mo/on (LSPM) Catalog contains 61, 977 stars with m>0.14 /yr and is believed to be over 99% complete for b >15, and V<19 LSPM at least 90% complete at lower la(tudes. Brown dwarf searches (Mee/ng the Cool Neighbors) complete for b >15.

6 WISE- 2MASS Advantages Both surveys are all- sky. WISE vs. 2MASS astrometry good to 0.2 2MASS K s is well matched to W1. Independent of the classical photographic surveys. Can detect very high mo:on objects. We have searched the WISE Preliminary Release for W1<12 and m>0.3 /yr.

7 Sample Object Source is high S/N in 2MASS and WISE. On POSS1 plate, is merged with faint background star.

8 Most new stars are M dwarfs Subset of data from Preliminary Release

9 Very High Mo(on Star An M4 dwarf 2.1 /yr ~13 parsecs 1992 DSS Scan

10 Results We have iden(fied 366 new proper mo(on stars (but only fily in north, many V>19) in Preliminary 3500 LSPM stars meet W1, m criteria. Completeness of LSPM is indeed 99% (including the Plane). We found no unknown bright stars (V<10) We found one very high proper mo:on star (so that list is also ~99% complete).

11 Nearby L dwarfs: An overview Cruz et al. (2007) 99 ultracool [M7- L8] dwarfs in 91 systems within 20 pc. Reid et al. (2007) 85 L dwarfs within 20 parsecs Add SDSS Table from Looper et al (2008)

12 W L7.5 dwarf 0.42 /yr 8.8 +/- 1.0 pc K=12.4 Gizis, Burgasser, Fahert, et al. 2011

13 W Gizis, Burgasser, Fahert, et al. 2011

14 W L9 dwarf 0.57 /yr 7.8 pc Castro & Gizis, SDSS image

15 W L9 dwarf 0.57 /yr 7.8 pc Castro et al., 2012

16 W /yr b=33 Confused/ extended

17 Spectrum, colors point to L9 at 10 pc

18 Spectrum, colors point to L9 at 10 pc Castro et al., 2012

19 W Gizis et al. (2012), submi\ed

20 W is unusually red at all bands K s = /yr Gizis, Faherty, Liu, et al. 2012

21 W IRTF SpeX Gizis, Faherty, Liu, et al. 2012

22 Comparison to known red L dwarfs Gizis, Faherty, Liu, et al Spectra from Looper et al (2008), Pa(ence et al.(2010)

23 Conclusions W is reddest field L dwarf: J- K=2.55 +/ (2MASS) Very good match to 2M Color similar to 2M Spectrum is not peaky like 2M1207b or earlier type low- g red L dwarfs. Probably not low surface gravity. Although, mo(on is consistent with b Pic.

24 Comparison to theore(cal models See Tsuji (2002), Stephens et al. (2009), Madhusdhan et al. (2011)

25 Theore(cal Remarks In each of the three model families considered, one can produce red L dwarfs by changing a free parameter. Stephens et al.: f sed = 1. Madhu models A or AE, clouds extend higher Tsuji T cr =1600K; dust is at cooler layers. We have not considered high metallicity.

26 Other L dwarfs In total, eight spectroscopically (7 IRTF SpeX) confirmed new L dwarfs within 20 parsecs. Similar number of unconfirmed candidates. One L dwarf is of special interest: W

27 Kepler Mission

28 This L1 dwarf is bright enough to be measured by Kepler. Kepler L Dwarf

29 This L dwarf may be modeled by a single spot with P=8.9 hours Dark spot not unlike those seen in Kepler M dwarfs (GO )

30 Summary We are comple(ng the L dwarf census at low galac(c la(tudes. Four of the six closest L7- L9 dwarfs discovered by WISE, but we need parallaxes. Although sta(s(cally incremental, these sources are of great value, as demonstrated by the extremely red source (W0047) and the Kepler source (W1906.)