1999ApJ...527..219S


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.30CET23:06:44

1999ApJ...527..219S - Astrophys. J., 527, 219-229 (1999/December-2)

Keck spectra of brown dwarf candidates and a precise determination of the lithium depletion boundary in the α Persei open cluster.

STAUFFER J.R., BARRADO Y NAVASCUES D., BOUVIER J., MORRISON H.L., HARDING P., LUHMAN K.L., STANKE T., McCAUGHREAN M., TERNDRUP D.M., ALLEN L. and ASSOUAD P.

Abstract (from CDS):

We have identified 27 candidate very low mass members of the relatively young α Persei open cluster from a 6 deg2 CCD imaging survey. Based on their I magnitudes and the nominal age and distance to the cluster, these objects should have masses less than 0.1 M if they are cluster members. We subsequently obtained intermediate-resolution spectra of 17 of these objects using the Keck II telescope and Low-Resolution Imaging Spectrograph (LRIS). We also obtained near-IR photometry for many of the stars. Our primary goal was to determine the location of the ``lithium depletion boundary'' and, hence, to derive a precise age for the cluster. Most of our program objects have radial velocities consistent with cluster membership, moderately strong Hα emission, and spectral types of M5.5 to M8, as expected from their (R-I)C colors. We detected lithium with equivalent widths greater than or equal to 0.4 Å in five of the program objects. We have constructed a color-magnitude diagram for the faint end of the α Persei main sequence, including stars for which high signal-to-noise spectra in the region of the lithium λ6708 absorption line have been obtained. These data allow us to accurately determine the α Persei single-star lithium depletion boundary at M(IC)=11.47, Mbol=11.42, (R-I)C0=2.12, spectral type M6.0. By reference to theoretical evolutionary models, this converts fairly directly into an age for the α Persei cluster of 90±10 Myr. That age is considerably older than most previously quoted ages for the cluster but consistent with ages estimated from the upper main-sequence turnoff using recent models that include a moderate amount of convective core overshoot. At this age, the two faintest of our spectroscopically confirmed members should be substellar (i.e., brown dwarfs) according to theoretical models.

Abstract Copyright:

Journal keyword(s): Stars: Hertzsprung-Russell Diagram - open clusters and associations: individual (α Persei) - Stars: Abundances - Stars: Low-Mass, Brown Dwarfs

Nomenclature: Table 2: Cl* Melotte 20 AP NNN (Nos 300-326).

Simbad objects: 40

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Number of rows : 40

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 Cl* Melotte 20 AP 300 LM* 03 17 27.5609132333 +49 36 52.860540135           M6: 5 0
2 Cl* Melotte 20 AP 301 LM* 03 18 09.0623721726 +49 25 18.961211033           M6.5 5 0
3 Cl* Melotte 20 AP 302 LM* 03 19 08.4674221316 +48 43 46.292755058           ~ 3 0
4 Cl* Melotte 20 AP 303 LM* 03 19 10.9222161502 +48 42 18.411475750           ~ 5 0
5 Cl* Melotte 20 AP 304 LM* 03 19 13.2444446505 +48 31 53.536147452           ~ 3 0
6 Cl* Melotte 20 AP 305 LM* 03 19 21.5939158612 +49 23 30.894856298       20.594 18.355 ~ 4 0
7 Cl* Melotte 20 AP 306 LM* 03 19 41.3517511377 +50 30 45.011136385           M8 5 0
8 Cl* Melotte 20 AP 268 LM* 03 19 47.4490576822 +48 58 44.386914065           M5 8 0
9 Cl* Melotte 20 AP 307 LM* 03 20 21.1080747276 +48 01 03.426681364           ~ 5 0
10 Cl* Melotte 20 AP 270 LM* 03 20 43.4756364068 +50 59 39.652785612           ~ 9 0
11 Cl* Melotte 20 AP 308 LM* 03 20 59.8439974328 +48 18 36.092699478           ~ 5 0
12 Cl* Melotte 20 AP 309 LM* 03 22 40.6669537741 +48 00 33.635143527       18.226 16.378 M5 8 0
13 V* V601 Per BY* 03 23 03.3723884718 +48 53 05.805808258     21.21     M6 19 0
14 Cl* Melotte 20 AP 310 LM* 03 23 04.8334022512 +48 16 11.136717146       19.678 17.657 M6.0 6 0
15 Cl* Melotte 20 AP 311 LM* 03 23 08.6711143291 +48 04 50.617103453       19.564 17.497 M6.0 6 0
16 Cl* Melotte 20 AP 312 LM* 03 23 15.0221138262 +48 11 55.019533989           M5.5 3 0
17 Cl* Melotte 20 AP 313 LM* 03 24 08.1109052854 +48 48 29.740036661       19.531 17.539 ~ 4 0
18 * alf Per V* 03 24 19.3700924 +49 51 40.245455 2.64 2.27 1.79     F5Ib 804 1
19 Cl* Melotte 20 AP 314 LM* 03 25 19.4234719079 +49 17 59.094739704           M5.5 3 0
20 Cl* Melotte 20 AP 315 LM* 03 26 34.1169656740 +49 07 46.132429155           M6.5 3 0
21 Cl Melotte 20 OpC 03 26 42 +48 48.0           ~ 761 0
22 Cl* Melotte 20 AP 316 LM* 03 27 00.9880447311 +49 14 40.869297739       19.713 17.670 M6.0 4 0
23 Cl* Melotte 20 AP 284 LM* 03 27 05.5933091667 +47 25 29.943600865           M4.5 10 0
24 Cl* Melotte 20 AP 165 LM* 03 28 03.0713966821 +50 40 19.054569439           M3.2 8 0
25 Cl* Melotte 20 AP 317 LM* 03 28 06.0212386051 +48 45 12.413466605           ~ 3 0
26 Cl* Melotte 20 AP 318 LM* 03 30 42.3736515244 +48 21 25.197992420           M6.0 5 0
27 Cl* Melotte 20 AP 319 LM* 03 31 03.1354741335 +49 02 55.782442989           ~ 4 0
28 Cl* Melotte 20 AP 320 LM* 03 31 25.2168193533 +49 02 51.057080321           ~ 3 0
29 Cl* Melotte 20 AP 321 LM* 03 32 18.7801837047 +49 32 15.857445361           ~ 4 0
30 Cl* Melotte 20 AP 322 LM* 03 33 08.4926233475 +49 37 55.157789282           M5.5 1 0
31 Cl* Melotte 20 AP 323 LM* 03 33 20.7087537116 +48 45 48.847108031           ~ 5 0
32 Cl* Melotte 20 AP 324 LM* 03 33 48.1734764112 +48 52 28.254970002           M6.5 4 0
33 Cl* Melotte 20 AP 296 LM* 03 35 40.3075391832 +48 26 27.514386456           M4.7 4 0
34 Cl* Melotte 20 AP 325 LM* 03 35 47.3620811173 +49 17 43.097358182           M7.0 5 0
35 Cl* Melotte 20 AP 326 LM* 03 38 55.0926521814 +48 57 28.010748322           M7.5 4 0
36 Cl Melotte 22 OpC 03 47 00 +24 07.0           ~ 3037 0
37 Cl* Melotte 22 PPL 15 LM* 03 48 04.6589395721 +23 39 30.327153356         17.91 M6.5 96 0
38 NGC 2516 OpC 07 58 04 -60 45.2           ~ 597 0
39 NGC 2547 OpC 08 09 52.360 -49 10 35.01           ~ 319 0
40 IC 2391 OpC 08 40 32 -53 02.0           ~ 725 0

    Equat.    Gal    SGal    Ecl

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2020.11.30-23:06:44

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