THE FIRST DAYS OF DEBRIS Exciting Results and Unexpected (Good) Surprises

Jane Greaves (St Andrews), for Brenda Matthews (HIA) & The DEBRIS team INTRODUCTION

 Debris discs are rarefied discs

 parent population of (invisible) rocky/icy 5/6/10

planetestimals

 second-generation dust produced by their collisions ESLAB 2010: Herschel First Results  For older, fainter discs, need sensitivity and resolution to detect them, due to confusion with background

2 THE DEBRIS SURVEY: SCIENCE

 Disc Emission via a Bias-free Reconnaissance in 5/6/10 the Infrared/Submillimetre

 Four primary science goals: ESLAB 2010: Herschel First Results  To establish the incidence of discs statistically  To place the in context (common or unusual)  To characterize the debris disc population  To resolve discs and model their structure

3 THE DEBRIS SURVEY: SAMPLE

 Targets drawn from Unbiased Nearby sample 5/6/10 (Phillips et al. 2010)

 ~90 each of A, F, G, K and M type primaries (446) ESLAB 2010: Herschel First Results  Sp. Type samples volume-limited, with confusion cut  Volume limits: 46, 24, 21, 16, 8.6 (A-M)

4 THE DEBRIS SURVEY: SENSITIVITY

 Flux-limited, uniform depth 5/6/10

 Driven by 100 micron sensitivity  1 sigma rms = 1.2 mJy at 100 micron ESLAB 2010: Herschel First Results  PACS 100/160  SPIRE followup for 98 targets (confusion limited)

5 DEBRIS: STATUS

 SDP observations 5/6/10  Seven targets observed with PACS

 All but one known disc hosts ESLAB 2010: Herschel First Results  Six discs detected  Single M observed: no disc OR STAR detected

 62 targets observed as of day 353 with PACS 100/160  5 targets observed with SPIRE (SDP)

6 FIRST RESULTS: BETA LEO 5/6/10

ESLAB 2010: Herschel First Results

. 5th closest A star to Sun (11 pc) . disc resolved for the first time! . 100 micron size 10.4 arcsec x 9.2 arcsec*

. SED is well fit by blackbody grains of temperature 112 K 7 * Beam is 6.7 arcsec x 6.9 arcsec Matthews et al. 2010, submitted FIRST RESULTS: BETA UMA 5/6/10

ESLAB 2010: Herschel First Results

. 24th closest A star to Sun (24.3 pc) . disc marginally resolved (one axis) . 100 micron size 8.4 arcsec x 7.3 arcsec

. SED is well fit by blackbody grains of temperature 109 K 8

Matthews et al. 2010, submitted FIRST RESULTS: ETA CORVI

494 WYATT ET AL. Vol. 620 5/6/10

ESLAB 2010: Herschel First Results

450 micron Wyatt et al. 2005

. 63rd F star from the Sun (18.2 pc) . disc resolved at 100 and 160 micron . 100 micron size 18.3 arcsec x 16.4 arcsec . emission double peaked at 160 micron

. SED requires two components Fig. 1.—SCUBA observations of  Corvi at: (a and b) 850 m with an effective resolution of 15B8; ( c and d ) 450 m with an effective resolution9 of 13B7; and (e and f ) 450 m with an effective resolution of 9B5. The(T top row= of31 images K (a, cand, e) show the354 surface K) brightness of the emission, while the bottom row (b, d, f ) show the signal-to-noise ratio of that emission. All maps are presented with a small amount of additional Gaussian smoothing: 300 in (a) and (b) and 400 in (c)–( f ). Contour 2 2 2 levels in the surface brightness images are linearly spaced at (a) 16, 20, ...Jy arcsecÀ ,(c) 72, 81, ... Jy arcsecÀ , and (e) 110, 118, ... Jy arcsecÀ . Contour . greybody grains 2longward of2 210 micron 2 levels in the signal-to-noise ratio images are linearly spaced at: (b) 3, 4, ... Jy arcsecÀ ,(d ) 4, 4.5, ... Jy arcsecÀ , and ( f ) 3.2, 3.6, ... Jy arcsecÀ . The axes show the offsets from the location of the star; north is up and east is to the left. The structure seen within 1500 of the star in (e) and ( f ) is consistent with two clumps of equal brightness both offset 5B5 from the starMatthews (see text for details). et al. 2010, submitted

data results in an image that contains two positive and two neg- Extended emission was detected centered on the star (here- ative images of any given source. The image was calibrated after source A) at each wavelength with greater than 5  con- using observations of the standard star HD 71701 taken imme- fidence. Another source (hereafter source B) was also detected diately before the science observation at an air of 1.5; the with >4  confidence at both wavelengths at 2400 north-  flux of the calibrator in this waveband, 6312 mJy, was derived northwest of  Corvi. The 10000 ; 10000 field around the star was from the template for the emission spectrum of this star given in analyzed to determine the noise level. Structure at <3  con- Cohen et al. (1999). A conservative estimate of the calibration fidence is found randomly distributed across the field of view accuracy was determined from the gain variation throughout the and has the same level and distribution as that expected from night to be 16%. The PSF of point sources on this night had noise.6 Thus, the zero levels in all maps were set to show only FWHM of betweenÆ 1B0 and 1B2. structure detected with >3  confidence. The remaining field is blank on this scale apart from a source (hereafter source C) 3. RESULTS detected with greater than 3  confidence 5000 southwest of 3.1. Submillimeter  Corvi at 850 m but not at 450 m; the edge of source C can just be seen in the bottom left corner of Figures 1a and 1b. The rebinned 850 and 450 m images of a 6700 ; 6700 region The fluxes, locations, and morphologies of these sources are centered on  Corvi are shown in Figure 1. Each 0B2 pixel in the discussed in more detail below. images represents the weighted mean of all bolometer measure- ments falling within 600 at 850 m (Fig. 1a), within 700 at 450 m 3.1.1. Source A: Circumstellar Disk (Fig. 1c), and within 400 at 450 m (Fig. 1e). The error is not The extended emission found centred on the star (source A) constant across the image because of the different noise levels we attribute to a circumstellar disk detected by IRAS in the far- in different bolometers, but its distribution in the region plotted 2 IR (e.g., Stencel & Backman 1991). Fitting a Gaussian to the can be approximated by Gaussians with 5:1 0:8 Jy arcsecÀ 2 Æ rebinned 850 m data indicates that the 850 m emission has a (Fig. 1a), 19 1:4 Jy arcsecÀ (Fig. 1c), and 34 3 Jy FWHM of 19B4 0B2 and is centered on the star to within 2 . 2 Æ Æ 00 arcsecÀ (Fig. 1e). This uncertainty is quantified in Figures 1b, Æ Æ 1d, and 1f, which show the corresponding signal-to-noise ratio 6 maps. The same rebinning methods were applied to the calibra- The expected noise distribution was determined by simulating an obser- vation of a blank field: each bolometer was assumed to see noise with a Gaussian tion data, which showed that point sources rebinned in this way distribution with the same standard deviation as the observed scatter in the are slightly smoothed and can be fitted by Gaussians of FWHM measurements for that bolometer (in that observation); these data were then 15B8 (Fig. 1a), 13B7 (Fig. 1c), and 9B5 (Fig. 1e). rebinned in the same way as the observations in Fig. 1. B. Matthews et al.: Resolving debris discs in the far-infrared with Herschel

B. Matthews et al.: Resolving debris discs in the far-infrared with Herschel

Fig. 1. Images of the 100 and 160 µm emission from three DEBRIS targets: β Leo, β UMa and η Corvi. Contours are shown at 0, 10, 30, 50, 60, 70, 80, 90 and 99% of the peak in each map. The 1-σ rms noise levels are given in Table 1. Circles in the upper left corner of each panel mark the nominal beam sizes for a scan speed of 20!!/s, i.e., 6!!. 7 and 11!! at 100 and 160 µm, respectively. The negative images created by the chop/nod observing mode are visible in the β UMa images. Striping in the η Corvi image at 160 µm is due to high 1/f noise and filtering artefacts.

(Poglitsch et al. (2010)) instrument. The results presented here Table 1. Stellar and Disc Parameters were taken during early testing phases or during the Science Demonstration Phase on Herschel (2009 Sept. - Dec.) Parameter β Leo β UMa η Corvi The images were obtained using two different observing UNS ID A005 A024 F063 strategies: point source chop/nod, and small scan-map modes HD number HD 102647 HD 95418 HD 109085 (see the PACS Observers’ Manual1). For point-source mode ob- Spec. Type A3 Va A1 V F2 V / PACS OM scan point-source scan servations, seven contiguous repeat chop nod observations were D [pc] 11.0 24.3 18.2 performed. Scan map observations had eight repeats in a single / !! ! rms100 [mJy beam] 1.4 3.1 1.2 scan direction at a rate of 20 /s. Four 3 scan legs were per- rms [mJy/beam] 3.9 7.6 5.0 Fig. 1. Images of the 100 and!! 160 µm emission from three DEBRIS targets: β Leo,160 β UMa and η Corvi. Contours are shown at 0, 10, 30, 50, 60, 70,formed 80, 90 per and map 99% with of the a peak 2 separation in each map. between The 1-σ legs.rms noise The levelstotal are givenAperture in Table [arcsec] 1. Circles in 20 the upper left corner 15 of each panel 20 mark theobserving nominal times beam sizes were for 1072 a scan and speed 1220 of seconds, 20!!/s, i.e., respectively, 6!!. 7 and 11!! at for 100 andF 160100 [mJy]µm, respectively. The 500 negative± 50 images 390 ± created39 by 300 the chop± 30/nod observingeach chop mode/nod areand visible scanning in the observation.β UMa images. Striping in the η Corvi imageF160 at 160[mJy]µm is due to high 230 1±/f46 noise and 120 filtering± 25 artefacts. 290 ± 58 100 !! Table 1 shows the survey (“UNS”) identifier for each FWHMmin [ ] 9.2 ± 0.17.2 ± 0.1 16.4 ± 0.4 FIRST100 RESULTS!! : DISC PARAMETERS target as well as the source and observing details. FWHMmaj [ ] 10.4 ± 0.18.4 ± 0.2 18.3 ± 0.4 (PoglitschPhillips et al.et al. (2010) (2010)) contains instrument. details The of the results development presented of here the TablePA100 1. Stellar[◦] and Disc Parameters125 ± 3 114 ± 5 102 ± 7 ∗ wereUnbiased taken Nearby during Stars early sample testing from phases which or the during DEBRIS the Science targets L [L$] 13.5 60 5.0 T ∗ [K]β 8380β 9340η 6950 Demonstrationare drawn. Phase on Herschel (2009 Sept. - Dec.) Parametere f f Leo UMa Corvi 5/6/10 = ∗ × −5 × −5 × −4 TheThese images data were were reduced obtained using using the Herschel two differentinteractive observing pro- UNSfD L IDIR/L 2.2 A00510 1.4 A02410 3.6 F06310 strategies: point source chop/nod, and small scan-map modes HDTdisc number[K] HD 112 102647 HD 109 95418 HD 31, 109085 354 cessing environment (HIPE, Ott (2010)). Maps were obtained ESLAB 2010: Herschel First Results 1 Spec.Rdust [AU] Type A3 23 Va A1 51 V 174, F2 V 1.4 via(see the the default PACS Observers’ PACS na¨ıve Manual map-making). For point-source methods photProject mode ob- a ∼ ∼ ∼ / PACSRobs [AU] OM scan39 point-source47 scan145 andservations,photProjectPointSource seven contiguousin repeat HIPE chopfor thenod scanning observations and point were D(a) [pc] 11.0 24.3 18.2 performed. Scan map observations had eight repeats in a single a derivedEstimates from of FWHM radius are deconvolved from the beam, assuming source observing modes respectively. Scanned data were pre- rms100 [mJy/beam] 1.4100 3.1100 2 1.2 !! ! Robs/D = sqrt(FWHMmin × FWHMma j −BEAM ). scanfiltered direction to remove at a low rate frequency of 20 /s. (1 Four/f ) noise 3 scan using legs a boxcar were per- fil- rms [mJy/beam] 3.9 7.6 5.0 !! Beta160 Leo and Beta UMa measured disc sizes ~ RKB formed per map with a 2! separation between legs. The total Aperture [arcsec] 20 15 20 ter with width equal to 1.5. All bright sources in the map were  Beta Leo observing times were 1072 and 1220 seconds, respectively, for onF the100 [mJy] distribution of targets 500 ± 50 will be 390 discussed± 39 in a 300 survey± 30 de- masked prior to filtering to avoid filter ringing type artefacts. The  R < R (BB fit radius is too small) eachchop/ chopnod configuration/nod and scanning meant observation. that no equivalent filtering was re- scriptionF160 [mJy] paperdust (B.obs Matthews 230 ± 2010,46 in 120 preparation).± 25 290 ± 58  grains100 !! are small, ±inefficient radiators± ± quiredTable for the 1 shows data obtained the survey in point (“UNS”) source mode. identifier for each FWHMmin [ ] 9.2 0.17.2 0.1 16.4 0.4 FWHM characteristic100 [!!] 10particle.4 ± 0.18 size, a.4 <± λ0.2/2π = 1816.3 micron± 0.4 targetAll threeas well targets as presented the source in this and paper observing are shared details. targets maj Phillips et al. (2010) contains details of the development of the 3.PA Results Beta100 [◦] UMa 125 ± 3 114 ± 5 102 ± 7 with the DUNES Herschel Key Programme (PI: C. Eiroa) which ∗ L [L$] 13.5 60 5.0 Unbiasedhas science Nearby goals Starscomplementary sample from to which those of the DEBRIS. DEBRISDetails targets  Rdust = Robs Fig.T ∗ 1 shows[K] the 100 and 8380 160 µm images 9340 for the three 6950 targets. are drawn. e f f blackbody grains present in this disc Thef rms= L levels/L∗ achieved2. in2 × each10−5 observation1.4 × 10− are5 summarized3.6 × 10−4 in 1 Thesehttp://herschel.esac.esa.int data were reduced/Docs using/PACS the/Herschelhtml/pacs interactiveom.html pro- TableD  1. blackbody TheIR higher fit noise unconstrained levels associated in submm with the point-source Tdisc [K] 112 109 31, 354 10 cessing environment (HIPE, Ott (2010)). Maps were obtained  RdustSPIRE[AU] data forthcoming 23 for 51both sources 174, 1.4 via the default PACS na¨ıve map-making methods photProject R a [AU] ∼ 39 ∼ 47 ∼ 145 2 obs and photProjectPointSource in HIPE for the scanning and point (a) Estimates of radius are deconvolved from the beam, assuming source observing modes respectively. Scanned data were pre- 100 100 2 Robs/D = sqrt(FWHM × FWHM −BEAM ). filtered to remove low frequency (1/f ) noise using a boxcar fil- min ma j ter with width equal to 1.!5. All bright sources in the map were masked prior to filtering to avoid filter ringing type artefacts. The on the distribution of targets will be discussed in a survey de- chop/nod configuration meant that no equivalent filtering was re- scription paper (B. Matthews 2010, in preparation). quired for the data obtained in point source mode. All three targets presented in this paper are shared targets 3. Results with the DUNES Herschel Key Programme (PI: C. Eiroa) which has science goals complementary to those of DEBRIS. Details Fig. 1 shows the 100 and 160 µm images for the three targets. The rms levels achieved in each observation are summarized in 1 http://herschel.esac.esa.int/Docs/PACS/html/pacs om.html Table 1. The higher noise levels associated with the point-source

2 B. Matthews et al.: Resolving debris discs in the far-infrared with Herschel

B. Matthews et al.: Resolving debris discs in the far-infrared with Herschel

Fig. 1. Images of the 100 and 160 µm emission from three DEBRIS targets: β Leo, β UMa and η Corvi. Contours are shown at 0, 10, 30, 50, 60, 70, 80, 90 and 99% of the peak in each map. The 1-σ rms noise levels are given in Table 1. Circles in the upper left corner of each panel mark the nominal beam sizes for a scan speed of 20!!/s, i.e., 6!!. 7 and 11!! at 100 and 160 µm, respectively. The negative images created by the chop/nod observing mode are visible in the β UMa images. Striping in the η Corvi image at 160 µm is due to high 1/f noise and filtering artefacts.

(Poglitsch et al. (2010)) instrument. The results presented here Table 1. Stellar and Disc Parameters were taken during early testing phases or during the Science Demonstration Phase on Herschel (2009 Sept. - Dec.) Parameter β Leo β UMa η Corvi The images were obtained using two different observing UNS ID A005 A024 F063 strategies: point source chop/nod, and small scan-map modes HD number HD 102647 HD 95418 HD 109085 (see the PACS Observers’ Manual1). For point-source mode ob- Spec. Type A3 Va A1 V F2 V / PACS OM scan point-source scan servations, seven contiguous repeat chop nod observations were D [pc] 11.0 24.3 18.2 performed. Scan map observations had eight repeats in a single / !! ! rms100 [mJy beam] 1.4 3.1 1.2 scan direction at a rate of 20 /s. Four 3 scan legs were per- rms [mJy/beam] 3.9 7.6 5.0 Fig. 1. Images of the 100 and!! 160 µm emission from three DEBRIS targets: β Leo,160 β UMa and η Corvi. Contours are shown at 0, 10, 30, 50, 60, 70,formed 80, 90 per and map 99% with of the a peak 2 separation in each map. between The 1-σ legs.rms noise The levelstotal are givenAperture in Table [arcsec] 1. Circles in 20 the upper left corner 15 of each panel 20 mark theobserving nominal times beam sizes were for 1072 a scan and speed 1220 of seconds, 20!!/s, i.e., respectively, 6!!. 7 and 11!! at for 100 andF 160100 [mJy]µm, respectively. The 500 negative± 50 images 390 ± created39 by 300 the chop± 30/nod observingeach chop mode/nod areand visible scanning in the observation.β UMa images. Striping in the η Corvi imageF160 at 160[mJy]µm is due to high 230 1±/f46 noise and 120 filtering± 25 artefacts. 290 ± 58 100 !! Table 1 shows the survey (“UNS”) identifier for each FWHMmin [ ] 9.2 ± 0.17.2 ± 0.1 16.4 ± 0.4 FIRST100 RESULTS!! : DISC PARAMETERS target as well as the source and observing details. FWHMmaj [ ] 10.4 ± 0.18.4 ± 0.2 18.3 ± 0.4 (PoglitschPhillips et al.et al. (2010) (2010)) contains instrument. details The of the results development presented of here the TablePA100 1. Stellar[◦] and Disc Parameters125 ± 3 114 ± 5 102 ± 7 ∗ wereUnbiased taken Nearby during Stars early sample testing from phases which or the during DEBRIS the Science targets L [L$] 13.5 60 5.0 T ∗ [K]β 8380β 9340η 6950 Demonstrationare drawn. Phase on Herschel (2009 Sept. - Dec.) Parametere f f Leo UMa Corvi 5/6/10 ∗ −5 −5 −4 UNSfD = L IDIR/L 2.2 A005× 10 1.4 A024× 10 3.6 F063× 10 TheThese images data were were reduced obtained using using the Herschel two differentinteractive observing pro- 494 WYATT ET AL. Vol. 620 strategies: point source chop/nod, and small scan-map modes HDTdisc number[K] HD 112 102647 HD 109 95418 HD 31, 109085 354 cessing environment (HIPE, Ott (2010)). Maps were obtained ESLAB 2010: Herschel First Results 1 Spec.Rdust [AU] Type A3 23 Va A1 51 V 174, F2 V 1.4 via(see the the default PACS Observers’ PACS na¨ıve Manual map-making). For point-source methods photProject mode ob- a ∼ ∼ ∼ / PACSRobs [AU] OM scan39 point-source47 scan145 andservations,photProjectPointSource seven contiguousin repeat HIPE chopfor thenod scanning observations and point were D(a) [pc] 11.0 24.3 18.2 a derivedEstimates from of FWHM radius are deconvolved from the beam, assuming performed.source observing Scan map modes observations respectively. had Scanned eight repeats data in were a sing prele- / 100 100 2 !! ! rms100 [mJyRobs/Dbeam]= sqrt(FWHM 1.4× FWHM 3.1−BEAM ). 1.2 scanfiltered direction to remove at a low rate frequency of 20 /s. (1 Four/f ) noise 3 scan using legs a boxcar were per- fil- rms [mJy/beam] 3.9min 7.6ma j 5.0 !!  Eta160 Corvi is well resolved, as expected formed per map with a 2.! separation between legs. The total Aperture [arcsec] 20 15 20 ter with width equal to 1 5. All bright sources in the map were  150 AU radius measured at 450 micron observingmasked prior times to filtering were 1072 to avoid and 1220filter ringing seconds, type respectively, artefacts. The for onF the100 [mJy] distribution of targets 500 ± 50 will be 390 discussed± 39 in a 300 survey± 30 de-  Similar morphologies at 160 and 450 micron eachchop/ chopnod configuration/nod and scanning meant observation. that no equivalent filtering was re- scriptionF160 [mJy] paper (B. Matthews 230 ± 2010,46 in 120 preparation).± 25 290 ± 58  100100 micron!! morphology± suggests± warmer component± within quiredTable for the 1 shows data obtained the survey in point (“UNS”) source mode. identifier for each FWHMmin [ ] 9.2 0.17.2 0.1 16.4 0.4 100 !! target as well as the source and observing details. FWHMcoolmaj [(31] K) outer10. 4ring± 0. 18(proposed.4 ± 0by.2 Chen 18 .et3 ± al.0. 42006) All three targets presented in this paper are shared targets ◦ Phillips et al. (2010) contains details of the development of the 3.PA Results100 Generally[ ] suggests125 ± radial3 distribution 114 ± 5 of 102 material± 7 is with the DUNES Herschel Key Programme (PI: C. Eiroa) which ∗ Unbiasedhas science Nearby goals Starscomplementary sample from to which those of the DEBRIS. DEBRISDetails targets L [L$broader] than the 13.5 two ring system 60 of Wyatt 5.0 et al. (2005) Fig.T ∗ 1 shows[K] the 100 and 8380 160 µm images 9340 for the three 6950 targets. are drawn. e f f As for Beta UMa, R = R Thef rms= L levels/L∗ achieved2. in2 × each10obs−5 observationdust1.4 × 10− are5 summarized3.6 × 10−4 in 1 These// data were reduced/ using/ the/Herschel/ interactive pro- D IR absence of small, inefficiently radiating grains http: herschel.esac.esa.int Docs PACS html pacs om.html TableT 1.[K] The higher noise levels 112 associated 109 with the point-s 31, 354ource 11 cessing environment (HIPE, Ott (2010)). Maps were obtained disc R dustSPIRE[AU] data forthcoming 23 51 174, 1.4 via the default PACS na¨ıve map-making methods photProject a Robs [AU] Fig. 1.—SCUBA observations∼ 39 of  Corvi at: (a and b) 850∼m47 with an effective resolution∼ of145 15B8; ( c and d ) 450 m with an effective resolution of 13B7; and (e and f ) 450 m with an effective resolution of 9B5. The top row of images (a, c, e) show the surface brightness of the emission, while the bottom row (b, d, f ) show and2 photProjectPointSource in HIPE for the scanning and point (a)  the signal-to-noise ratio of that emission. All maps are presented with a small amount of additional Gaussian smoothing: 300 in (a) and (b) and 400 in (c)–( f ). Contour Estimates of radius are deconvolved from the beam,2 assuming 2 2 levels in the surface brightness images are linearly spaced at (a) 16, 20, ...Jy arcsecÀ ,(c) 72, 81, ... Jy arcsecÀ , and (e) 110, 118, ... Jy arcsecÀ . Contour 100 100 2 2 2 2 source observing modes respectively. Scanned data were pre- R /levelsD in= thesqrt(FWHM signal-to-noise ratio images are× linearlyFWHM spaced at: (b) 3, 4,−...BEAMJy arcsecÀ ,(d).) 4, 4.5, ... Jy arcsecÀ , and ( f ) 3.2, 3.6, ... Jy arcsecÀ . The axes obs show the offsets from the location of themin star; north is up and eastma is to j the left. The structure seen within 1500 of the star in (e) and ( f ) is consistent with two clumps filtered to remove low frequency (1/f ) noise using a boxcar fil- of equal brightness both offset 5B5 from the star (see text for details). ! ter with width equal to 1.5. All bright sources in the map were data results in an image that contains two positive and two neg- Extended emission was detected centered on the star (here- masked prior to filtering to avoid filter ringing type artefacts. The on the distributionative images of of any targets given source. will The be image discussed was calibrated inafter asurvey source A) at eachde- wavelength with greater than 5  con- using observations of the standard star HD 71701 taken imme- fidence. Another source (hereafter source B) was also detected diately before the science observation at an air mass of 1.5; the with >4  confidence at both wavelengths at 2400 north- chop/nod configuration meant that no equivalent filtering was re- scription paper (B. Matthews 2010, in preparation).  flux of the calibrator in this waveband, 6312 mJy, was derived northwest of  Corvi. The 10000 ; 10000 field around the star was quired for the data obtained in point source mode. from the template for the emission spectrum of this star given in analyzed to determine the noise level. Structure at <3  con- Cohen et al. (1999). A conservative estimate of the calibration fidence is found randomly distributed across the field of view All three targets presented in this paper are shared targets accuracy was determined from the gain variation throughout the and has the same level and distribution as that expected from 3. Results night to be 16%. The PSF of point sources on this night had noise.6 Thus, the zero levels in all maps were set to show only with the DUNES Herschel Key Programme (PI: C. Eiroa) which FWHM of betweenÆ 1B0 and 1B2. structure detected with >3  confidence. The remaining field is blank on this scale apart from a source (hereafter source C) has science goals complementary to those of DEBRIS. Details Fig. 1 shows the 100 and3. 160 RESULTSµm images for thedetected three with targets. greater than 3  confidence 5000 southwest of 3.1. Submillimeter  Corvi at 850 m but not at 450 m; the edge of source C can The rms levels achieved in each observation are summarizedjust be seen in the bottom in left corner of Figures 1a and 1b. 1 The rebinned 850 and 450 m images of a 6700 ; 6700 region The fluxes, locations, and morphologies of these sources are http://herschel.esac.esa.int/Docs/PACS/html/pacs om.html Table 1. The highercentered on  noiseCorvi are levels shown in Figure associated 1. Each 0B2 pixel with in the thediscussed point-s in moreource detail below. images represents the weighted mean of all bolometer measure- ments falling within 600 at 850 m (Fig. 1a), within 700 at 450 m 3.1.1. Source A: Circumstellar Disk (Fig. 1c), and within 400 at 450 m (Fig. 1e). The error is not The extended emission found centred on the star (source A) constant across the image because of the different noise levels we attribute to a circumstellar disk detected by IRAS in the far- 2 in different bolometers, but its distribution in the region plotted 2 IR (e.g., Stencel & Backman 1991). Fitting a Gaussian to the can be approximated by Gaussians with 5:1 0:8 Jy arcsecÀ 2 Æ rebinned 850 m data indicates that the 850 m emission has a (Fig. 1a), 19 1:4 Jy arcsecÀ (Fig. 1c), and 34 3 Jy FWHM of 19B4 0B2 and is centered on the star to within 2 . 2 Æ Æ 00 arcsecÀ (Fig. 1e). This uncertainty is quantified in Figures 1b, Æ Æ 1d, and 1f, which show the corresponding signal-to-noise ratio 6 maps. The same rebinning methods were applied to the calibra- The expected noise distribution was determined by simulating an obser- vation of a blank field: each bolometer was assumed to see noise with a Gaussian tion data, which showed that point sources rebinned in this way distribution with the same standard deviation as the observed scatter in the are slightly smoothed and can be fitted by Gaussians of FWHM measurements for that bolometer (in that observation); these data were then 15B8 (Fig. 1a), 13B7 (Fig. 1c), and 9B5 (Fig. 1e). rebinned in the same way as the observations in Fig. 1. SUMMARY 5/6/10  Resolution impact is immediate  Beta Leo and Beta UMa discs resolved for the first ESLAB 2010: Herschel First Results time (Beta UMa along one axis only)  Disc sizes are comparable to (40-50 AU)  Among smallest discs yet resolved  Target sensitivity limits are reachable in scan- mapping mode F037 – PACS 100 micron  1.2 mJy/beam at 100 micron  vs. 5 mJy/beam at 70 micron from Spitzer (Trilling et al. 2008) +  More results are coming fast! 12