2022A&A...661A..44S


Query : 2022A&A...661A..44S

2022A&A...661A..44S - Astronomy and Astrophysics, volume 661A, 44-44 (2022/5-1)

A first eROSITA view of ultracool dwarfs.

STELZER B., KLUTSCH A., COFFARO M., MAGAUDDA E. and SALVATO M.

Abstract (from CDS):

We present the first X-ray detections of ultracool dwarfs (UCDs) from the first all-sky survey of the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) onboard the Russian Spektrum-Roentgen-Gamma mission. We use three publicly available input catalogs of spectroscopically confirmed UCDs and Gaia-selected UCD candidates that together comprise nearly 20000 objects. In a careful source identification procedure we first extracted all X-ray sources from the catalog of the first survey, eRASS1, that have a UCD or candidate within three times their positional uncertainty. Then we examined all Gaia objects in the vicinity of these 96 X-ray sources and we associated them to the most plausible counterpart on the basis of their spatial separation to the X-ray position and their multiwavelength properties. This way we find 40 UCDs that have a secure identification with an X-ray source (that is bonafide UCD X-ray emitters) and 18 plausible UCD X-ray emitters for which we consider it likely that the X-ray source has its origin in the UCD. Twenty-one of the bonafide and plausible X-ray emitting UCDs have a spectroscopic confirmation, while the others have been selected based on Gaia photometry and we computed spectral types from the G-J color. The spectral types of the X-ray emitting UCDs and candidates range between M5 and M9. The distances of the eRASS1 UCDs range from 3.5 to 190 pc. The spectroscopically confirmed UCDs at the high end of the distance distribution are known to be members of nearby star forming regions. The majority of the UCDs from the eRASS1 sample show a ratio of X-ray to bolometric luminosity well above the canonical saturation limit of log (Lx/Lbol) ~= -3. For the two most extreme outliers, we verified the hypothesis that these high values are due to flaring activity through an analysis of the eRASS1 light curve. X-ray spectra could be analyzed for the two brightest objects in terms of count rate, both showing an emission-measure weighted plasma temperature of <kT> = 0.75 keV. These observations demonstrate the potential of eROSITA for advancing our knowledge on the faint coronal X-ray emission from UCDs by building statistical samples for which the average X-ray brightness, flares, and coronal temperatures can be derived.

Abstract Copyright: © ESO 2022

Journal keyword(s): X-rays: stars - stars: activity - stars: coronae - stars: flare - brown dwarfs

VizieR on-line data: <Available at CDS (J/A+A/661/A44): table1.dat table2.dat>

CDS comments: Section 6.1. : the object 2MASS J08533434-0329432 does not exist; Gaia DR2 5761985432616501376 is LP 666-9 = 2MASS J08533619-0329321.

Simbad objects: 109

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Number of rows : 109
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 2MASS J00464077-5739515 BD? 00 46 40.7705810472 -57 39 51.586960428           ~ 2 0
2 Gaia DR3 5000837474517057920 BD? 00 48 44.1033935784 -37 32 36.986155332           ~ 2 0
3 2MASS J01021362-6322445 BD? 01 02 13.6402821768 -63 22 44.572499688           ~ 2 0
4 2MASS J01104526-3620561 BD? 01 10 45.2703150221 -36 20 56.135619204       14.510   ~ 2 0
5 2MASS J01433761-7845558 BD? 01 43 37.6424215200 -78 45 55.615059720           ~ 2 0
6 LP 884-42 BD? 01 49 56.3041043136 -31 22 36.662732076     18.80     ~ 5 0
7 Gaia DR2 4693915709930430720 BD? 01 56 38.7573173784 -70 18 42.501742992           ~ 2 0
8 Gaia DR2 4713089165493934848 BD? 01 58 50.1010514088 -62 56 39.544715508           ~ 2 0
9 Gaia DR2 4936518694287842816 BD? 02 10 55.5338238312 -52 28 22.275276204           ~ 2 0
10 2MASS J02192210-3925225 ** 02 19 22.1103954432 -39 25 22.539937296   18.5   15.5 13.42 M6+L4 19 0
11 2MASS J02571481-4124488 BD? 02 57 14.8222836888 -41 24 48.833056440           ~ 2 0
12 Gaia DR3 5056274919508375680 BD? 03 36 19.1232404760 -29 24 49.563632880           ~ 2 0
13 SCR J0336-2619 LM* 03 36 31.4539394256 -26 19 57.951974172           M5.5 10 0
14 LEHPM 3479 BD? 03 42 35.2427467068 -36 30 33.613162640           ~ 6 0
15 Gaia DR2 5108858895603072768 BD? 03 42 53.5122411840 -16 27 18.597829248           ~ 2 0
16 SIPS J0401-4253 BD? 04 01 55.0227339792 -42 53 33.553815864       18.74 15.889 ~ 4 0
17 2MASS J04152749-5643225 BD? 04 15 27.5079373824 -56 43 22.515371635           ~ 5 0
18 Gaia DR2 4780991778106390912 BD? 04 21 36.4319801832 -52 07 35.368990860           ~ 2 0
19 2MASSI J0422205-360608 PM* 04 22 20.5962323256 -36 06 07.922683440           M6.5 4 0
20 SIPS J0429-4405 BD? 04 29 02.3425539264 -44 05 46.305212532           ~ 3 0
21 LP 655-48 PM* 04 40 23.2746368923 -05 30 08.125383990   18.9 17.79 15.72 13.36 M7.5Ve 56 0
22 FBS 0444-113B PM* 04 46 51.6818367888 -11 16 47.509528008           M6 1 0
23 FBS 0444-113 ** 04 46 51.72816 -11 16 47.5932     12.252 11.928   M3.0V 20 0
24 FBS 0444-113A PM* 04 46 51.7832900592 -11 16 47.654712588           M5e 1 0
25 APMPM J0452-5819 PM* 04 51 37.3352701629 -58 18 52.047330868     18.507 16.429 14.136 M6.5V 8 0
26 2MASS J05095818-3833276 BD? 05 09 58.1912676960 -38 33 27.615666348           ~ 2 0
27 SIPS J0519-5435 BD? 05 19 26.0003069712 -54 35 33.136812096           ~ 5 0
28 2MASS J05251524+2102394 BD? 05 25 15.2757810696 +21 02 39.567863508       19.5 17.0 ~ 3 0
29 Gaia DR2 2968787330365930112 BD? 05 27 31.9389360840 -19 44 22.752126420           ~ 2 0
30 Gaia DR3 4768473902647140608 * 05 35 25.0225194096 -54 52 44.408060472           ~ 2 0
31 Gaia DR3 2887886428728021632 BD? 05 51 47.3793780048 -34 56 18.595075632           ~ 2 0
32 2MASS J06004140-1023433 BD? 06 00 41.3965263168 -10 23 43.314799632           ~ 2 0
33 2MASS J06150465+2513244 BD? 06 15 04.6501938024 +25 13 24.440666556           ~ 2 0
34 Gaia DR3 2999407900270881280 BD? 06 23 10.6540243176 -14 12 56.904353784           ~ 2 0
35 SIPS J0648-6537 BD? 06 48 43.5229460328 -65 37 21.640468080       18.53 15.081 ~ 4 0
36 Gaia DR2 5281637080508351488 BD? 06 53 47.9290368048 -67 21 28.132338960           ~ 2 0
37 2MASS J07093348-6007086 BD? 07 09 33.4743447600 -60 07 08.668267428           ~ 2 0
38 2MASS J07161895-7238353 BD? 07 16 18.9690356112 -72 38 35.422141056           ~ 2 0
39 Gaia DR2 5267560411093993472 BD? 07 29 37.2365510808 -70 24 14.592558564           ~ 2 0
40 Gaia DR2 3060426058267356928 BD? 07 30 30.3938058912 -03 39 33.603450084           ~ 2 0
41 Gaia DR2 5274924557723534464 BD? 07 38 06.2694845400 -67 07 37.872242112           ~ 2 0
42 LSPM J0739+1305 PM* 07 39 43.8429389616 +13 05 06.843521868           M8 5 0
43 BD+13 1727 PM* 07 39 44.1030809064 +13 04 56.489967912       9.1   K5 6 0
44 LP 423-31 PM* 07 52 23.9250338268 +16 12 14.957934141   17.7 16.73 15.8   M6.0V 51 0
45 2MASS J08054717+3837179 LM* 08 05 47.1828957528 +38 37 18.028626492           M7V 4 0
46 CD-37 4268 * 08 07 29.8538920824 -37 54 27.428496696   10.59 9.96     ~ 2 0
47 2MASS J08073107-3754402 BD? 08 07 31.0671502584 -37 54 40.399436700           ~ 2 0
48 2MASS J08273677+1627590 BD? 08 27 36.7731568008 +16 27 59.006672388           ~ 2 0
49 G 51-15 Er* 08 29 49.3527921926 +26 46 33.624143059   16.87   14.736   M6.5Ve 273 0
50 LSR J0833+3706 BD? 08 33 03.0987440298 +37 06 08.278409485   19.5   18.0   ~ 8 0
51 V* AZ Cnc Er* 08 40 29.6791626163 +18 24 08.726250637   19.2 17.59 16.6 13.45 M6.0V 80 0
52 SCR J0850-0318 PM* 08 50 08.6136909696 -03 18 26.192908008   12.49 11.661 11.214 9.77 M1 6 0
53 2MASS J08500913-0318305 BD? 08 50 09.1207084704 -03 18 30.506899968           ~ 2 0
54 2MASS J08524304-5516548 BD? 08 52 43.0429904976 -55 16 54.948425520           ~ 2 0
55 TYC 8573-3247-1 * 08 52 44.8427710416 -55 17 00.640657248   11.35 10.86     ~ 2 0
56 LP 666-9 LM* 08 53 36.1604798120 -03 29 32.197505547     18.959 16.781 14.487 M9Ve 238 0
57 2MASS J09034867+3948190 BD? 09 03 48.6651473688 +39 48 19.006641000           ~ 2 0
58 Gaia DR2 5624087604843625472 BD? 09 06 42.1901287896 -35 48 21.634711740           ~ 3 0
59 SDSS J092634.07+281642.2 LM* 09 26 34.0803801672 +28 16 42.100573512           M7 3 0
60 2MASSI J0952219-192431 LM* 09 52 21.8872375272 -19 24 32.203844316     18.349 16.402 14.199 M7Ve 28 0
61 2MASS J09554268-4616060 BD? 09 55 42.6866649024 -46 16 06.042294876           ~ 2 0
62 LP 609-24 LM* 10 03 19.1591671629 -01 05 08.000660498   21.0 21.0   14.94 M7e 27 0
63 Gaia DR2 5667753914566385664 BD? 10 08 19.4881558848 -19 54 00.563812596           ~ 2 0
64 TWA 22 LXB 10 17 26.8927745040 -53 54 26.387425044   15.69 13.96 13.72   M5 77 0
65 G 44-9 PM* 10 20 44.0727319896 +08 14 23.386519860   16.2   13.7   M5.9V 22 0
66 Gaia DR2 5354836757890090880 BD? 10 21 36.5451181776 -56 35 53.778535332           ~ 2 0
67 2MASS J10283359-8115054 BD? 10 28 33.5443316424 -81 15 05.432281704           ~ 3 0
68 TWA 34 LM* 10 28 45.7992409512 -28 30 37.525747356       15.82   M5e 30 0
69 Gaia DR2 5364671030411595904 BD? 10 35 31.0843622568 -48 16 46.271807148           ~ 2 0
70 Gaia DR2 3754497583659096320 BD? 10 39 58.4387887272 -12 03 57.611156616           ~ 2 0
71 BD-03 3000 PM* 10 49 59.7159972936 -04 15 47.720887812   10.62 9.74     ~ 2 0
72 2MASS J10500015-0416072 BD? 10 50 00.1495903224 -04 16 07.323605184           ~ 2 0
73 2MASS J10502610-4357527 BD? 10 50 26.0922422208 -43 57 52.670437200           ~ 2 0
74 SIPS J1055-3332 BD? 10 55 11.6449789368 -33 32 23.397457020           ~ 3 0
75 NAME TW Hya Association As* 11 01.9 -34 42           ~ 897 0
76 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1077 1
77 CHXX 16 LM* 11 10 22.2523149192 -76 25 13.841167332         16.58 ~ 29 0
78 2MASS J11134796-2347212 BD? 11 13 47.9415917640 -23 47 21.338688120           ~ 2 0
79 Gaia DR2 5226806600296754816 BD? 11 31 00.8662161840 -73 45 10.726970076           ~ 2 0
80 2MASS J12053396+0358145 LM* 12 05 33.9609854880 +03 58 14.477619000           M7V 4 0
81 2MASS J12093743-7106405 BD? 12 09 37.4444462880 -71 06 40.599413460           ~ 2 0
82 SDSS J123337.60+073132.7 QSO 12 33 37.6078017744 +07 31 32.766273516   20.07 19.61     ~ 17 0
83 2MASS J12333789+0731380 BD? 12 33 37.8947158728 +07 31 37.927996068           ~ 2 0
84 Gaia DR3 5838354551048094592 BD? 12 37 18.4637646288 -75 16 17.661304236           ~ 2 0
85 2MASS J12523253-5542399 * 12 52 32.5384939176 -55 42 39.975081156           ~ 2 0
86 2MASS J12523513-5013236 BD? 12 52 35.1239740704 -50 13 23.709641556           ~ 2 0
87 TYC 8662-1667-1 * 13 33 17.7485762760 -53 51 13.030125012   12.21 11.25     ~ 5 0
88 2MASS J13331887-5351213 BD? 13 33 18.8810773680 -53 51 21.371395968           ~ 2 0
89 LP 558-26 BD? 13 41 32.9346774048 +08 05 04.884488628   19.7   17.2   ~ 9 0
90 2MASS J14110102-7425254 BD? 14 11 01.0480682568 -74 25 25.398820596           ~ 3 0
91 2MASS J14192177-4647055 * 14 19 21.7748587032 -46 47 05.505323532           ~ 2 0
92 NAME beta Pic Moving Group MGr 14 30 -42.0           ~ 691 0
93 2MASS J14330612-5958181 BD? 14 33 06.1204923480 -59 58 18.174072576           ~ 2 0
94 2MASS J14490017-4822273 BD? 14 49 00.1736802312 -48 22 27.278567976           ~ 2 0
95 LP 914-54 Er* 14 56 38.2634715567 -28 09 48.619153485     17.141 14.863 12.433 M7.0Ve 146 0
96 TVLM 868-54745 PM* 15 00 34.2473417136 -00 59 44.806652988           ~ 5 0
97 2MASS J15345704-1418486 LM* 15 34 56.9323418001 -14 18 49.252078924           M8.6V 23 0
98 UCAC4 195-119117 PM* 15 40 43.5364511947 -51 01 35.965163897       15.08   M6.5 14 0
99 LP 860-41 PM* 15 52 44.6116720802 -26 23 13.708406460   17.4       M6.0V 18 0
100 2MASS J16094285-4531181 BD? 16 09 42.8381321952 -45 31 17.963628816           ~ 2 0
101 2MASS J16163503-2057551 Y*O 16 16 35.0383171680 -20 57 55.210247136           M5.5 9 0
102 2MASS J17432426-6856206 BD? 17 43 24.2587352664 -68 56 20.723923716           ~ 2 0
103 CD-68 1857 PM* 17 43 27.5200462752 -68 56 15.817683444   9.26 8.70     ~ 10 0
104 2MASS J17452539-8211494 * 17 45 25.4074077120 -82 11 49.547359464           ~ 2 0
105 2MASS J17564670-7743087 BD? 17 56 46.7002417152 -77 43 08.718099924           ~ 2 0
106 Gaia DR3 6414644917704872832 BD? 18 10 09.7684328928 -75 08 05.689781232           ~ 2 0
107 Gaia DR3 6669379355016434560 BD? 20 21 44.7842157792 -47 09 38.035610496           ~ 2 0
108 Gaia DR2 6369404201815106688 BD? 20 58 17.4629155800 -75 19 18.998387256           ~ 2 0
109 Gaia DR2 6349997791519306496 BD? 21 04 54.8491790256 -78 54 40.876321824           ~ 2 0

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2022.10.05-14:06:27

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